The Alternative Energy Matrix

[An updated treatment of this material appears in Chapter 17 of the Energy and Human Ambitions on a Finite Planet (free) textbook.]

Breathe, Neo. I’ve been running a marathon lately to cover all the major players that may provide viable alternatives to fossil fuels this century. Even though I have not exhausted all possibilities, or covered each topic exhaustively, I am exhausted. So in this post, I will provide a recap of all the schemes discussed thus far, in matrix form. Then Do the Math will shift its focus to more of the “what next” part of the message.

The primary “mission” of late has been to sort possible future energy resources into boxes labeled “abundant,” “potent” (able to support something like a quarter of our present demand if fully developed), and “niche,” which is a polite way to say puny. In the process, I have clarified in my mind that a significant contributor to my concerns about future energy scarcity is not the simple quantitative scorecard. After all, if it were that easy, we’d be rocking along with a collective consensus about our path forward. Some comments have  asked: “If we forget about trying to meet our total demand with one source, could we meet our demand if we add them all up?” Absolutely. In fact, the abundant sources technically need no other complement. So on the abundance score alone, we’re done at solar, for instance. But it’s not that simple, unfortunately. While the quantitative abundance of a resource is key, many other practical concerns enter the fray when trying to anticipate long-term prospects and challenges—usually making up the bulk of the words in prior posts.

For example, it does not much matter that Titan has enormous pools of methane unprotected by any army (that we know of!). The gigantic scale of this resource makes our Earthly fossil fuel allocation a mere speck. But so what? Practical considerations mean we will never grab this energy store. Likewise, some of our terrestrial sources of energy are super-abundant, but just a pain in the butt to access or put to practical use.

In this post, we will summarize the ins and outs of the various prospects. Interpretation will come later. For now, let’s just wrap it all up together.

The Matrix

Would you like to know what the matrix is? Okay. I’ll tell you—in a bit. For each of the major energy hopefuls I have discussed on Do the Math, I characterize their various attributes in a three-tier classification: adequate (green); marginal (yellow); or insufficient (red)—possibly a showstopper. The scheme is qualitative, and I am sure some will disagree with my assignments. Before I go any further, let me say that I will not entertain comments griping about why I made a certain square the color I did. I won’t have time to respond at that level, given that there are 200 colored boxes in the matrix. But the beauty is, you can change the matrix any way you see fit and make your own custom version. Go buy some crayons today!. The matrix I’ve created is not without its biases and subjectivity. Whose would be?

Okay, I’ll keep the suspense going a bit by describing the fields.

Abundance: This is essentially the “abundant,” “potent,” and “niche” classification scheme reflected in the preceding posts. Green means that the resource can in principle produce far more power than we currently use and keep it up for many centuries. Red means a bit-player at best. Yellow is the stuff that can be useful, but is incapable of carrying the full load—not that we require everything to do this. We can tolerate a mix of of items, but will not get far by mixing reds together.

Difficulty: This field tries to capture the degree to which a resource brings with it large technical challenges. How many PhDs does it take to run the plant? How painful is it to maintain or keep churning? This one might translate into economic terms: difficult is another term for expensive.

Intermittency: Green if rock-steady or there whenever we need it. If the availability is beyond our control, then it gets a yellow at least. The possibility of going without for a few days earns a red.

Demonstrated: I don’t mean on paper, and I don’t mean a prototype that exhibits some of the technology. To be green, this has to be commercially available today, and providing useful energy.

Electricity: Can the technology produce electricity? Most of the time, the answer is yes. Sometimes it would make no sense to try. Other times, it is seriously impractical.

Heat: Can the resource produce direct heat? Yellow if only through electric means.

Transport: Does the technology relieve the liquid fuels crunch? Anything that makes electricity can power an electric car, earning a yellow score. Liquid fuels are green. Some may get tired of the broken record in the descriptions that follow that a particular resource does not help transportation, wanting to shout “electric cars, fool” every time I say it. But our large-scale migration to electric cars is not in the bag. They may remain too expensive to be widely adopted. Meanwhile, this does not help air travel or heavy transport.

Acceptance: Is public opinion (I can really only judge U.S. attitudes) favorable to this method? Will there likely be resistance—whether justified or not?

Backyard?: Is this something that can be done domestically, in one’s backyard or small property, managed by the individual?

Efficiency: Over 50% gets the green. Below about 10% gets red. It’s not the most important of criteria, as the abundance score incorporates efficiency expectations. But we will always view low efficiency negatively.

Okay, enough holding out—here’s the matrix (click to expand; see here for colorblind-friendly version).

Yellow boxes tend to deserve explanation. It is usually clear why something would swing red or green, but yellow often has several things tugging at it. If green boxes are given a +1 score, yellow boxes zero, and red boxes −1, adding the boxes with equal weight yields the scores on the right, by which measure the table is sorted: best to worst. The only place I cheated was to give D-D fusion a −2 for difficulty. It’s the hardest thing on the list, given our decades of massive effort invested to date on D-T fusion, while D-D is too hard to even attempt.

Now, equal weighting on all ten criteria is boneheaded. But the assessment is imprecise enough not to warrant a more elaborate weighting scheme. I do not stand firm behind the order that results, and am half-tempted to monkey with weighting schemes until a more preferred order emerges. But I would be cooking the books to further match my preferences. Feel free to weight any way you see fit, and change anything else while you’re at it. Just remember. No griping.

Fossil Fuels, Compared

Note that conventional fossil fuels, matrixed-out above, score green in almost every category, except—unfortunately—abundance (see here for R/G colorblind version). The efficiency is high for direct heating (most often natural gas), and middling for electricity or transport. Coal gets no points for transportation, and natural gas is of limited use here (although the bus I’m riding as I type this is powered by natural gas, so I can’t entirely nix its transportation capability). All things considered, all of the fossil fuels get a score of 7 or 8. Note the striking gap we face between fossil fuels and their alternatives, topping out at a score of 5. One might ding the fossil fuels a point or two for their greenhouse gas contributions, closing the gap a bit.  None of the options in the alternatives matrix are intrinsic carbon emitters.

Quick Lessons

Looking at some of the main trends, very few options are both abundant and easy. Solar PV and solar thermal qualify. A similar exclusion principle often holds for abundant and demonstrated/available. There is a reason why folks (myself included) like solar.

Intermittency mainly plagues solar and wind resources, with mild inconvenience appearing for many of the natural sources.

Electricity is easy to produce. We have loads of ways to do it, and are likely to pick the easiest/cheapest. We won’t necessarily get far down the list if we’re covered by things at the top end (assuming my rankings have any validity and some economic correlation).

Transport is hard. Concerns over peak oil played a huge role in making me sit up to pay attention to our energy challenges. Electric cars are the most obvious way out, but don’t do much for heavy shipping by land or sea, and leave airplanes on the ground.

Few things face serious barriers to acceptance: especially when energy scarcity is at stake.

A few options are available for the homestead. A passive solar home with PV panels, wind, and some method to produce liquid fuels on site would be a dream come true. Here’s hoping for artificial photosynthesis!

The missing category here is cost, although difficulty may be an imperfect proxy. As a result, some of the high-scoring options may more be costly than we’d like. Actually, some of the lowest-scoring options are the costliest! If you’re expecting that we’ll replace fossil fuels and do it on the cheap, you might as well learn to bawl on the floor kicking and pounding your fists, tears streaming. This is our predicament. We have to buck up and deal with it, somehow.

Individual Discussion

For each topic, the link at the beginning points to a more complete discussion on Do the Math.  Here, I just briefly characterize each resource in relation to the matrix criteria.

Solar PV: Covering only 0.5% of land area with 15% efficient PV panels provides the annual energy needs of our society, qualifying solar PV as abundant. It’s not terribly difficult to produce; silicon is the most abundant element in Earth’s crust, and PV panels are being produced globally at 25 GW peak capacity per year (translating to 5 GW of average power added per year). Intermittency is the Achilles Heel of solar PV, requiring storage solutions if adopted at large scale. Solar PV produces electricity directly, which could be converted to heat or transport. Most people do not object to solar PV on rooftops or over parking areas, or even in open spaces (especially desert). I’ve got some on my garage roof as we speak (with storage), so they’re well-suited to individual operation/maintenance. Clocking in at an efficiency of 15%, don’t expect PV to vastly exceed this ballpark.

Solar Thermal: Achieving comparable efficiency to PV, but using more land area, generating electricity from concentrated solar thermal energy automatically fits in the abundant category—though somewhat more regionally constrained. It’s relatively low-tech: shiny curved mirrors tracking on (often) one axis, heating oil or other fluid to run a plain-old heat engine. Intermittency can be mitigated by storing thermal energy, perhaps even for a few days. Because a standard heat-engine follows, fossil fuels can supplement in lean times using the same back-end. A number of plants are already in operation, producing cost-competitive electricity—and heat if anyone cares. As with so many of the alternatives, transportation is not directly aided. Public acceptance is no worse than for PV, etc. But don’t expect your own personal solar thermal electricity plant.

Solar Heating: On a smaller scale, heat collected directly from the sun can provide domestic hot water and home heating. In the latter case, it can be as simple as a south-facing window. Capturing and using solar heat effectively is not particularly difficult, coming down to plumbing, insulation, and ventilation control. Technically, it might be abundant, but since it is usually restricted to building footprints (roof, windows), I take it down a notch. There will be lean days, but my friends in Maine do not complain about their solar heating comfort (with occasional propane backup). Solar heating is useless for electricity or transport, but has no difficulty being accepted and almost by definition is a backyard-ready technology.

Hydroelectric: We have seen that super-efficient hydroelectric is doomed to remain a small player (in the rubric that we maintain today’s energy consumption levels). It’s the low-hanging fruit of the renewable world, and has therefore already seen large-scale development. It has seasonal intermittency (typical capacity factor for a hydro plant is 40%), does not directly provide heat or transport, and can only rarely be implemented personally, at home. Acceptance is fairly high, although silting and associated dangers—together with habitat destruction—do cause some opposition to expanded hydroelectricity.

Biofuels from Algae: I was somewhat surprised to see this entry rank as highly as it did in my admittedly unsophisticated scoring scheme. Because it captures solar energy—even at < 5% efficiency—the potential scale is automatically enormous. But it’s not easy, at present. Dealing with slime will bring challenges of keeping the plumbing clean, possible infection in a genetic arms race with evolving viruses, contamination by other species, etc. At present, we don’t have that magic algal sample that secretes the fuels we want. Heady talk of genetic engineering pledges to solve these problems, but we’re simply not there yet and cannot say for sure that we will get there. Otherwise, the ability to provide transportation fuel is the big draw. Heat may also be efficiently produced, though electricity would represent a misallocation of liquid fuel. Can it be done in the backyard? I could imagine a slime pond in the yard, but care and feeding and refining the product may be prohibitively difficult.

Geothermal Electricity: This option makes sense primarily at geological hotspots, which are rare. It will not scale to be a significant part of our entire energy mix. Aside from this, it is relatively easy, steady, and well-demonstrated in many locations. It can provide electricity, and obviously direct heat—although far from heat demand, generally. It provides no direct help on transportation. Objections are slim to non-existent. I don’t think houses tend to be built on the hotspots, so don’t look for it in a backyard near you.

Wind: Wind is a sensible option that I imagined would float higher in the list than it did. It’s neither abundant nor scarce, being one of those options that can provide a considerable fraction of our present needs under large-scale development. It’s pretty straightforward, reasonably efficient, and demonstrated the world over in large farms. The biggest downside is its intermittency. It will not be unusual to have a few days in a row with little or no regional input. Like so many other things, electricity is naturally produced, while heat and transport is only available via electricity. I sense that objections to wind are more serious than for many other alternatives. Windmills are noisy and tend to be located in prominent places (ridge-tops) where they are extremely visible and scenery-altering. You can’t hide wind in a bowl, or you end up hiding from the wind at the same time. Another built-in conflict emerges on wind-rich coastlines, where many like to take in unspoiled scenery. Small-scale wind is viable in your own backyard.

Artificial Photosynthesis: A very appealing future prospect for me is artificial photosynthesis, combining the abundance of direct solar with the self-storing flexibility of liquid fuel. Intermittency is thus eliminated to the extent that annual production meets demand: storage of a liquid fuel for many months is possible. The dream result of a panel sitting on your roof that drips liquid fuel could provide both heating and transportation fuel. In a pinch, one could also produce electricity this way, but what a waste of precious liquid fuel, when we have so many other ways to make electricity! The catch is that it doesn’t exist yet, that it may never exist, and that feeding it the right ingredients and processing/refining the fuel may eliminate the backyard angle. Still, we all have to have something to gush over. For some, it’s thorium and for others it’s fusion, etc. This one excites me by its potential to satisfy so many purposes.

Tidal Power: Restricted to select coastal locations, tidal will never be a large contributor on the global scale. The resource is intermittent on daily and monthly scales, but in a wholly predictable manner. Extracting tidal energy is not terribly hard—sharing technology with similarly efficient hydroelectric installations—and has been demonstrated in a number of locations around the world. It’s another electricity technique, with no direct offering of heat or transportation. No unusual level of societal objection exists, to my knowledge, but it’s not something you will erect in your backyard and expect to get much out of it.

Conventional Fission: Using conventional uranium reactors and conventional mining practices, nuclear fission does not have the legs for a marathon. On the other hand, it is certainly well-demonstrated, and has no problems with intermittency—unless we count the fact that it has trouble being intermittent in the face of variable load. Compared to other options, nuclear runs a tad on the high-tech side. By this I mean that design, construction, operation, and emergency mitigation require more brains and sophistication than the average energy producer. Nuclear fission directly produces heat (seldom utilized), and is primarily used to generate electricity via the standard steam-driven heat engine, but offers no direct help on transportation. Acceptance is mixed. Germany plans to phase out its nuclear program even though they are serious about carbon reduction. No new plants have been built in the U.S. for over thirty years in part due to public discomfort. Some of this is irrational fear over mutant three-eyed fish and the like, but some is genuine political difficulty relating to the pesky waste problem that no country has yet solved to satisfaction. Nuclear power is not possible on a personal scale.

Uranium Breeder: Extending nuclear fission to be able to use the 140-times more abundant 238U (rather than 0.7% 235U) gives uranium fission the legs to run for at least centuries if not a few millennia, so abundance issues disappear. Breeding has been practiced in military reactors, and indeed some significant fraction of the power in conventional uranium reactors comes from 238U turned 239Pu. But no commercial power plants have been built to deliberately access the bulk of uranium, turning it into plutonium at scale for the purpose of power production. Public acceptance of breeders will face even stiffer hurdles because plutonium is more easily separated into bomb material than is 235U, and the trans-uranic radioactive waste from this option is nastier than for the conventional cousin.

Thorium Breeder: Thorium is more abundant than uranium, and only comes in one flavor naturally, so that abundance is not an issue. Like all reactors, thorium reactors fall into the high-tech camp, and include new challenges (e.g., liquid sodium) that conventional reactors have not faced. There have been a few instances of small-scale demonstration, but nothing in the commercial realm, so that we’re probably a few decades away from being able to bring thorium online. Public reaction will be likely be similar to that for conventional nuclear: not a show stopper, but some resistance on similar grounds. It is not clear whether the newfangled aspect of thorium will be greeted with suspicion or with an embrace. Though also a breeding technology (making fissile 233U from 232Th), the proliferation aspect is severely diminished for thorium due to highly radioactive 232U by-product and virtually no easily separable plutonium. Of the future nuclear prospects, I am most optimistic about this one—although it’s no nirvana to me.

Geothermal Heating with Depletion: A vast store of thermal energy sits in the crust, locked in the rock and moving slowly outward. Being the impatient lot that we are, we could drill down and grab the energy out of the rock on our own schedule, effectively mining heat as a one-time resource. In the absence of water flow to convect heat around, dry rock will deplete its heat within 5–10 meters of the borehole in a matter of a few years, requiring another hole 10 meters away from the first, and so on and so on. I classify this as moderately difficult, requiring a never-ending large-scale drilling operation across the land. The temperatures are pretty marginal for running heat engines to make electricity with any respectable efficiency (especially given so many easier options for electricity), but at least the thermal resource will not suffer intermittency problems during the time the hole is still useful. Given its inconvenience (kilometers of drilling), I do not know if examples abound of people having tried this for the purpose of providing heat in arbitrary (not geologically hot) areas. Public acceptance may be less than lukewarm given the scale of drilling involved, dealing with tailings and possibly groundwater contamination issues on a sizable scale. While such a hole could fit in a backyard, it would be far more practical to use the heat for clusters of buildings rather than for just one—given the amount of effort that goes into each hole (and considering short-term lifetime of each hole). I gave this technique high marks for efficiency if used for heat, but it would drop to reddish-yellow if we tried to use this resource for electricity.

Geothermal Heating, Steady State: If we turn our noses up at depletion-based geothermal heat, steady state offers far less total potential, coming to about 10 TW of flow if summed acrossall land. And to access temperatures hot enough to be useful for heating purposes, we’re talking about boreholes at least 1 km deep. It is tremendously challenging to cover any significant fraction of land area with thermal collectors 1 km deep. So I am probably being too generous to color this one yellow for the abundance factor. That’s okay, because I’m hitting it hard enough on the other counts. To gather enough steady-flow heat to provide for a normal U.S. home’s heat, the collection network would have to span a square 200 m on a side at depth, which seems nightmarish to me. But at least depletion would not be an issue in this circumstance. Otherwise, this category shares similar markings and rationale as the depletion scenario.

Biofuels from Crops: We’ve seen that corn ethanol is a loser of a scheme on energy grounds, although sugar cane and vegetable oils fare better. But these compete with food production and arable land availability, so biofuels from crops can only graduate from “niche” to “potent” in the context of plant waste or cellulosic conversion. I have thus split the abundance and demonstration in two: food crop energy is demonstrated but severely constrained in scale. Celluosic matter becomes a potent source, but undemonstrated (perhaps this should even be red). I do not label the prospect as an easy one, because growing and harvesting annual crops on a relavent scale constitutes a massive, perpetual job. If exploiting fossil fuels is akin to spending our inheritance, growing and harvesting our energy on an annual basis is like getting a real job—a real hard job. The main benefit of biofuels from crops is that we get a liquid fuel out of it—so hard to come by via other alternatives. Public acceptance hinges on competition with food or just land in general. Scoring only about 1% efficient at raking in solar energy, this option requires commandeering massive tracts of land. A small-time farmer may make useful amounts of fuel for themselves in their back “yard,” if refining does not create a bottleneck.

Ocean Thermal: The ocean thermal resource uses the 20–30°C temperature difference between the deep ocean (a few hundred meters down) and its surface to drive a ridiculously low-efficiency heat engine. The heat content is not useful for warming any home (it’s not hot). But all the same, it’s a vast resource due to the sheer area of the solar collector. Large plants out at sea will be difficult to access and maintain, and transmitting power to land is no picnic either. The resource suffers seasonal intermittency at mid-latitudes, but let’s imagine putting these things all in the tropics to get around this. Sound hard, you say? Well yeah! That’s part of what makes ocean thermal difficult! No relevant/commercial scale demonstration exists. Like so many others, this is electricity only (and this time, far from demand). Probably nobody cares what we put to sea: out of sight, out of mind. Ocean thermal isnot a backyard solution!

Ocean Currents: Large-scale oceanic currents are slower than wind by about a factor of ten, giving a kilogram of current 1000 times less power than a kilogram of wind. Water density makes up the difference to make ocean current comparable to wind in terms of power per rotor area. Not all the ocean has currents as high as 1 m/s, so I put the total abundance in the same category as wind. Maybe accessing a thicker column of water than we can for wind should bump ocean currents up a bit, but the currents are relatively confined to surfaces. But why dunk a windmill underwater where it’s far from demand and difficult to access and maintain, when a comparable power can be had in dry air? So I classify this as difficult. On the plus side, the current should be rock solid, eliminating intermittency worries, unlike wind. Still, not one bit of our electricity mix comes from ocean currents at present, so it cannot be said to have been meaningfully demonstrated. For the remaining categories: it’s electricity only; who cares what’s underwater; and no backyard opportunity.

Ocean Waves: While they seem strong and ever-present, waves are a linear-collection phenomenon, and not an areal phenomenon. So there really isn’t that much arriving at shores all around the world (a few TW at best). It’s not particularly difficult to turn wave motion into useful electricity at high efficiency, and the proximity to land will make access, maintenance, and transmission far less worrisome than for the previous two cases. There will be some intermittency—largely seasonal— as storms and lulls come and go. I’ve seen a diverse array of prototype concepts, and a few are being tested at commercial scale. So this is further along then the previous two oceanic sources, but not so much as to get the green light. There will be moderate push-back from people whose ocean views are spoiled, or who benefit from natural wave energy hitting the coast. There are no waves in my backyard, and I hope to keep it this way!

D-T Fusion: The easier of the two fusion options, involving deuterium and tritium, represents a longstanding goal under active development for the last 60 years. The well-funded international effort, ITER, plans to accomplish a 480 second pulse of 500 MW power by 2026. This defines the pinnacle of hard. Fusion brings with it numerous advantages: enormous power density; moderate radioactive waste products (an advantage?!); abundant deuterium (though tritium is zilch); and surplus helium to liven up children’s parties. Fusion would have no intermittency issues, can directly produce heat (and derivative electricity), but like the others does not directly address transportation. The non-existant tritium can be knocked out of lithium with neutrons, and even through we are not awash in lithium, we have enough to last many thousands of years. We might expect some public opposition to D-T fusion due to the necessary neutron flux and associated radioactivity. Fusion is the highest-tech energy we can envision at present, requiring a team of well-educated scientists/technicians to run—meaning don’t plan on building one in your backyard, unless you can afford to have some staff PhDs on hand.

D-D Fusion: Replacing tritium with deuterium means abundance of materials is no concern whatsoever for many billions of years. As a trade, it’s substantially harder than D-T fusion (or we would not even consider D-T). D-D fusion requires higher temperatures, making confinement that much more difficult. It is for this reason that I gave D-D fusion a −2 score for difficulty. It’s not something we should rely upon to get us out of the impending energy pinch, which is my primary motivation.

End of an Era

Not only does this conclude the end of the phase on Do the Math where we evaluate the quantitative and qualitative benefits and challenges of alternatives to fossil fuels, it also points to the fact that we face the end of a golden era of energy. Sure, we managed to make scientific and cultural progress based on energy from animals, slaves, and firewood prior to discovering the fossil fuels. But it was in unlocking our one-time inheritance that we really came into our own.  Soon, we will see a yearly decrease in our trust fund dividend, forcing us to either adapt to less or try to fill the gap with replacements. What this post and the series preceding it demonstrates is that we do not have a delightful menu from which to select our future. Most of the options leave a bad taste of one form or the other.

When I first approached the subject of energy in our society, I expected to develop a picture in my mind of our grandiose future, full of alternative energy sources like solar, wind, nuclear, biofuels, geothermal, tidal, etc.  What I got instead was something like this matrix: full of inadequacies, difficulties, and show-stoppers. Our success at managing the transition away from fossil fuels while maintaining our current standard of living is far from guaranteed. If such success is our goal, we should realize the scale of the challenge and buckle down now while we still have the resources to develop a costly new infrastructure. Otherwise we get behind the curve, possibly facing unfamiliar chaos, loss of economic confidence, resource wars, and the unforgiving Energy Trap. The other controlled option is to deliberately adjust our lives to require fewer resources, preferably abandoning the growth paradigm at the same time. Can we manage a calm, orderly exit from the building? In either case, the first step is to agree that the building is in trouble. Techno-optimism keeps us from even agreeing on that.

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167 thoughts on “The Alternative Energy Matrix

  1. A fascinating series of articles. Thanks very much. PV panels on the roof it is. In any case I’d already pretty much given up on installing a thorium breeder reactor in the back garden…

    I’m surprised you’d give coal “zero points” for transportation. Trains and ships powered by coal used to be quite popular.

    • I always thought that the best thing about PV was that it made electricity directly. Everything else is just a way to boil water to make steam to turn a turbine.

      Simpler is better. I read that somewhere.

      • PV cells have an internal inefficiency of their own (about 36%?), and they use more energy and cost to make and maintain in comparison to a steam-turbine system.

        Furthermore they produce current in DC – this would have to be converted into AC for transmission, leading to inevitable transform losses (steam turbines produce power in AC so they bypass this).

        • If you look at end-to-end generation costs (build and maintenance) and overall efficiency, then there is little to pick between PV and Solar Thermal electric. More and more high power long distance transmission is now done using DC rather then AC as it is more efficient and cheaper even with the conversion at each end.

        • That is a good point.

          But something I have often wondered about is why it is necessary to have AC power at all.

          I understand there was a debate about whether long distance transmission lines should be dc or ac.

          There was actually some kind of DC transmission network in New York that was only shut down in the past few years. I can’t remember the details on it.

          AC won of course. Now we have HVDC lines.

          I kind of wonder whether it might not be worth it to retool everything to run on dc current. It is a huge effort, but in the end most things in the household either transform it into dc anyway, or could run just as easily on dc.

          I mean what fraction of our produced electrical power is lost by the transformers in most electrical products?

          • AC won because we had a ready means to step up and step down the voltage, relying on the fact that a changing magnetic field (induced by a changing current in a loop, for instance) would induce a current in another coil. The ratio of turns set the voltage ratio, which could be set arbitrarily.

            Nowadays we have switching technologies that can do DC-to-DC conversion at high efficiency. So we can do DC transmission without suffering the electromagnetic (ULF radio) loss that AC does. As you say, many of our devices want DC anyway, so we could avoid AC-to-DC conversion in each of our devices at home if DC were delivered to our door. But it’s not just as simple as that. Getting DC to the house will still likely require a battery of DC-to-DC converters because one device wants 5 volts and another 3, but the toaster wants 100+, etc. DC is also far more dangerous in terms of fire. An arc does not as likely self-extinguish since the voltage does not swing through zero 120 times per second.

          • The other reason is that 3 phase AC (and some single phase AC) machines are extroadinarily simple, robust and efficient. All the heavy lifting in industry is done using 3 phase AC.

            Most domestic level appliances and tools use either
            – a universal motor that can run on AC or DC
            (eg power tools)
            , – an induction (AC) motor with capacitor start (eg mixers, fridges, etc.)
            – a shaded pole (AC) motor (typically fans)
            – or, more recently, multi-winding DC motors with electronic commutation (eg washing machines)

            For bigger domestic appliances (eg large air conditioners) you usually have to have 3 phase power wired into your home.

          • One idea I have thought of to help save a decent bit of electricity is to have a single large AC-DC converter in each home instead of several of the “wall warts” that are of questionable efficiency.

            They already make pc power supplies that output 3.3, 5, 12 volts dc at very high efficiencies. The latest batch of Gold & platinium models can do ~ 90% efficiency from 120 AC –> DC, and ~92-93 efficiency from 240 AC–> DC.

  2. Wow that transportation column is scary!

    Only three green boxes: Bio-fuel/Algae, Artificial Photosynthesis, and Bio-fuel/Crops with the only having a green demonstrated being Bio-Crops Ethanol.

    I truly believe that transport is going to be the real problem in the future, especially in the US. Yes electricity will get more expensive once we can’t rely on coal so much, but almost all of the US transportation runs on liquid fossil fuel:
    Cars: gas, some diesel
    Trucks: diesel
    Container ships: diesel
    Trains (the few we actually use): mostly diesel some electric
    Planes/jets: Jet fuel

    So basically if diesel & gas went away tomorrow we would have a few electric trains (mostly regional/city) and the few electric cars that have been produced…

    Maybe as a future article could you discuss the feasibility of creating a large scale electric train system so that we can at least get goods across the country without diesel?

    • I would think that developing a large scale electric train system would relatively easy. We already have electric streetcars- just expand them. Nuclear power could also get a yellow for transportation, since nuclear powered ships are certainly possible (though expensive). But I think the personal car will have to be abandoned.

      To make matter worse, there’s two more advantages of oil that this
      chart doesn’t even address-
      fertilizer and plastic. Both very important and made from oil. We’re going to have to learn to live without those, too.

      • As for the train system: I didn’t mean the technology behind the trains. Yes we have the technology for the train system. I mean the crazy high costs of a train system. The cost per mile of an electric train track is going to be higher than a diesel track or a road. (I have no idea how much higher) Also can an electric train pull the same loads as a diesel train? I cannot recall seeing an electric train used for freight.

        I don’t know about fertilizer, but you can make some plastics without oil or with less oil. I know that several soda/water companies are already starting to advertise the fact that their bottle is “plant bottle”

        Dasani advertises their latest water bottles as: “*up to 30% plant based, 100% recycled bottle” I have no idea how much this adds to the cost or quality of the plastic.

        • Well for trains, in he calculates that they’re roughly 40 times more energy efficient than a car, mostly because they push much less air (proportionally). At that level of efficiency, I wonder if a solar-powered train would be possible? But if not, we’re going to need a widely-distributed energy grid anyway to make up for the indeterminacy of renewables, so while we’re doing that we could extend it to train tracks as well. But you’re right, none of this will be easy or cheap.

          I’m sure you’re right that there are ways to create synthetic plastic and fertilizer without oil, but then how much extra cost and pollution does that create?

        • Absolutely an electric train can haul what a diesel train can. As I understand it trains using diesel generators and electric transmissions dominate hauling because the characteristics of an electric transmission are superior to a mechanical transmission for heavy loads. The question is more about getting tall pantographs for the biggest loading gauges. Or something.

          I’m personally most interested in the potential for wind-surfing trains across the Great Plains.

          • Wind surfing trains? That is a good picture of the magnitude of the problem. How big would the sail need to be?

            Imagine trying to power every vehicle on the New Jersey Turnpike by putting a huge sail on each vehicle. OK, we wouldn’t do that. We would just build huge wind turbines and some sort of power distribution system to get the power down to the vehicles. Presto, we now have a wind powered turnpike. How many wind turbines per mile would you need along the turnpike to keep the same level of traffic flowing on the highway? Do the math, but I bet it would take a lot of wind turbines, even on a good day.

          • I was thinking about wingsails. They’re the best sails possible, more or less, and vehicles using them can achieve speeds of 2-3x wind velocity; of course, those have been carbon-fiber racing yachts and similar vehicles.

            But in the case of freight trains on the prairies, they don’t have to go super fast, and there are hopefully not too many tunnels, and there might even be steady winds.

            I’m going to be lazy about the math, though, because I only want them for steampunk train robberies.

        • Re: electric trains, they represent an investment. Electrified track costs more per mile to build than regular track, but I believe once built, costs less per passenger-mile or freight-ton-mile than diesel. For this reason electrified track (in the UK, at least) tends to be used for the shorter, more heavily used lines, which tend to transport people more often than freight. The commuter routes into cities tend to be electric but the longer inter-city routes use diesel. (There’s also the question of pollution- diesel loco fumes in a city are more of a problem than in sparsely occupied country)

          This is probably why you usually see those hundred-car trains full of rubble or whatever being hauled by diesel. As with so many of the things this blog covers, transitioning to electric could be done but it will be expensive, and in the fossil fuel age burning dinosaur juice is the cheaper option.

          • If we had to convert trains to electric on the cheap, would we perhaps go with some sort of third rail system rather than bulky, expensive, ugly overhead lines? Adding a live third rail would be very dangerous to people and animals, but perhaps we could shield it somewhat. If cities start becoming isolated for lack of proper inter-city transportation, it might be an option to get the trains moving.

        • Electric trains can pull much higher loads than diesel trains. That’s why all freight trains traversing the Alps are electric, for example. Diesel train engines would not be strong enough to haul the same load.

          Historically, mountain railroads were the first to be electrified (in Austria, railroad electrification started in the 1920s) because of better traction and the availability of cheap hydroelectricity (the Austrian Federal Railways even operate their own hydro plants). Today, almost all main railroad lines in Europe are electrified and some countries have close to 100% electrification.

          More information can be found here:

      • True that plastics are made of oil. You can make most of the plastics also from plant and animal materials. Less than 10% of the oil is used as raw materials for chemical industries, so in a way, if oil was saved for that purpose it would last many centuries. But it would be good if we could cut back on many uses of plastic as well, ftalates, BPA and other things are not very good for us humans. For fertilizers it is the energy in oil and gas or electricity we use. Nitrogen can also be fixated naturally, it is only because it is cheaper to make it via oil that it is made. Overall we can manage the agriculture sector without nitrogen fertilizers. It will lead to some changes in diets and production – to the better..

      • Speaking of transportation, I’d love to see an article on transportation and available alternatives and their effectiveness respectively.

        I’m mostly wondering how much could we potentially alleviate from the FF system with the most resourceful alternatives used.

    • He would also need to explain how we get the goods from over the ocean, without diesel ships or jet fueled planes. Sailed clipper ships??

      People want to bring manufacturing back to North America, this is one economic driving force.

      A simple goal would be to move as many things off of Oil/Gas as we can so as to save those resources for Planes and Heavy haul. Stop heating homes with oil, move cars to Hybrids and Elec, etc.

      • That would certainly help, but the problem is the way that oil is refined produces some of those products whether you really need them or not.

        Here is a breakdown by boiling range:
        Liquefied petroleum gas (LPG) −40
        Butane −12 to −1
        Petrol −1 to 180
        Jet fuel 150 to 205
        Kerosene 205 to 260
        Fuel oil 205 to 290
        Diesel fuel 260 to 315

        Or they can be viewed by what group they break down into: [moderator removed copied list for brevity].

      • Steve: According to Merchants of Grain (p. 84), four-masted, steel-hulled sailing vessels economically shipped grain from Australia to England until German U-boats showed up during WWII. Among the ships that participated in the unofficial “grain races” along this route, the best time was 83 days, but the average among the yearly winners was ~99 days.

        I wouldn’t be surprised if these sorts of ships make a comeback in the future, especially for shipping bulk cargo like coal or grain. The global shipping fleet is already easing off the throttle to conserve fuel (slow steaming), with Maersk’s fleet averaging 12 knots. (Based on a back of the envelope calculation with the help of, you could reasonably expect one of the grain racers to average ~5 knots on the Oz-UK route.)

        Had Maersk paid attention to peak oil, it probably wouldn’t have built seven ships designed to cruise at high speeds (30 knots). By the time they entered service, bunker fuel prices had more than doubled. Due to their design, they’re inefficient at low speeds, and as of 2010 several were mothballed in Scotland.


        It’s expensive but actually well within our engineering capability. Nuclear powered super haulers are also possible at those levels of funding.
        Now the only real question is what is actually worth shipping that far once global wages level off due to the shift in manufacturing. When the Americans can no longer afford cheap Chinese stuff we will be willing to work for low enough wages to move the manufacturing back.

    • I think we have to abandon the idea of a personal 1.5 – 2 ton vehicle. This is what is killing all the above suggestions.

      I have just set up an electric bike for my pregnant wife. It has a range of 50 km, and cost $3000, but much cheaper options exist. Its 200 W motor can accelerate me to about 35 km/h (~20 mph) without pedalling (I weigh about 70 kg — 120 lb). I am a fit cyclist, but think a moderatly fit person could easily commute 20 km (12 mi) each way on such a vehicle.

      If you are concerned about weather, set up a recumbant trike with a cover.

      The bike takes about 1.5 kWh to fully charge — for its range that’s about 1/100th what a car uses.

      Once you remove the personal car from our projected future, then everything above looks much more reasonable and plausible.

      Thanks for the great series of posts, Tom!

    • Europe’s getting covered in high speed rail, which is nearly always electric AIUI, so seems pretty feasible. As for costs said $20 million/lane mile for freeway expansion, $35 million for light-rail, which I’d guess to be similar to conventional rail, and says a GAO recommendation for assuming $50 million/mile for high speed rail.

      I don’t think there’s much danger of running out of liquid fuels where needed. Coal to liquid and gas to liquid are commercial techs, AFAIK, and biomass might feed the same processes, even though everyone’s chasing cellulosic ethanol. And there’s biodiesel already. Oil won’t vanish, it’ll get more expensive, likely getting reserved for planes and ships, then trains and trucks. I expect cities will rediscover light rail and trolleybuses.

    • I don’t know about US or UK but here, in Poland all train tracks are electic. As far as I travelled across Europe all trains are electric.

      This can be huge advantage for transport since we can get electricity from allmost anything.

      As for water travel. Lest just keep in mind, that ships travelled across ocean long before fossil fuels were discovered. So now we have possibly three power sources for ships – wind and fossil fuels. Third one is solar since we can have PV on top of a ship to run its turbines. There is nothing to prevent us from using at least two of this power sources simultaniously.

  3. In light of the hydrocarbon cost/abundance graph in your November 1 post (together with other uses for coal), I hope you’ll explain in a future post why you believe any of these alternative energy sources need to become more than niche players during the next two or three centuries. Aside from global warming, that is.

  4. Love the articles.

    Are you not being a little harsh on the prospects for Nuclear (Thorium in particular)?

    The public’s fear of nuclear energy seems entirely disproportionate to the reality, and this has certainly held nuclear back. With a little education, and oil prices north of $200 / barrel, this perception might change 🙂

    • I can agree that public fear of nuclear is disproportionate to the risk. But I can’t wave that reality away. Yes, it may be that off-scale prices overcome the fear, but it may also cause enough disruption to make advanced efforts harder to carry out. In any case, thorium does not replace liquid fuel, so it isn’t clear we will run to nuclear when oil prices run up. But hey, we do irrational things!

      • Tom,

        Wave the reality of irrational fear away? Given the options, such education would seem to be of paramount importance!

        Regarding transport, smaller, lighter, and driverless will get us more motion of people and commodities for our precious stored electric Joules.

  5. There is one thing I would criticize in these great articles: all comparisons are made to our current lever of energy use.

    The very first step should be scaling down our energy needs, while trying to keep the standard of living. I know the limitations of improving energy efficiency, but still there are lot’s of possibilities there.

    • I agree. First, show the everyday person that creating a future at our current energy levels is really hard, and maybe many will come to the same conclusion you did.

      • Maybe a subject for a future topic is that recycling and depolluting requires energy, so in a world where we fully recycle, avoid mining and clean up the past mess, we will still consume a lot of energy just for that. Some processes can use solar energy (say for instance bio accumulation of pollutants through some plants) but others require “higher quality” energy (for instance, recycling electronics to recover rare elements)

    • All of us who care can start by doing this ourselves and hoping/persuading others to follow suit. I do it for the economical reasons, arguably the best reason of all since the world runs on money.

    • Easier said than done. Not because it is a technological challenge, but because a human one. We already have several cars in the US that get 40+ MPG that are not hybrids, yet look at the best selling vehicles of last year along with their (city, combine, highway) mpg. Note I picked the smallest engine front wheel drive for the variations. So in practice these are BEST case numbers as many cars are offered with all-wheel or four-wheel-drive and multiple engine sizes which decrease the number further.

      1. Ford F150 (16, 18, 22)
      2. Chevrolet Silverado Pickup (15, 17, 21)
      3. Toyota Camry (22, 26, 33)
      4. Nissan Altima (23, 27, 32)
      5. Ford Escape (23, 25, 28)
      6. Ford Fusion
      7. Honda Accord
      8. Toyota Corolla
      9. Chevrolet Cruze
      10. Doge Ram Pickup

      I only did the first five’s mileages, but I think you can see my point. I high doubt most people need a F150 for their daily commute or grocery store run.

    • Well, while the US could use less energy — fewer cars, more efficient homes, not eating grain-fed livestock — most of the world needs more energy to achieve a decent modern standard of living. US uses 10 kilowatts/capita, IIRC Italy was the lowest developed country at 1/3 of that, world average is 2 kilowatts. And Italy has a nice climate, not one crying out for air conditioning — the US uses more energy than Europe for some legitimate reasons (as can be seen by comparing to Canada or Norway). And the climate change we have may call for desalination.

      Put another way, the US uses 3 TW, the world 14 TW. If we cut by 50%, that frees up 1.5 TW, but the world needs to go up to 20 TW just to catch up to Italy…

    • > There is one thing I would criticize in these great articles:
      > all comparisons are made to our current level of energy
      > use.

      Given that a lot of the world population is in so called ‘developing’ countries, countries that use as much as one fifth as much energy as the typical American, it’s reasonable to expect all the efficiency gains achieved in developed countries to be negated by standard of living improvements and population increases in developing countries. So it would be unreasonable to expect global energy use to go down… unless there is a shortage.

  6. Fortunately the problem with transport energy is not such a drama, or need not to be. A huge part of the transport work is caused by poor design of our cities. Another part is caused by global competition grown wild, which has given us a lot of cheap products, but also caused a lot of harm. That a spanner is thrown in this global competition is not necessarily such bad thing. Guys like me can’t fly around the globe and advise people in sustainable living – but I am happy to stay home more. In general, I think we humans are wasting so much time, money and energy on transport that it is rather a liberation to transport less. Ivan Illich calculated already forty years ago that the average speed of a car driver was about 7 km/hour, more or less the same as walking – if you considered the time spent to earn money for the car, the petrol and the infrastructure.

    Great post Tom. Thanks

    • One big problem is that private automobile is the keystone of the corporate capitalist economy. Our cities and our lives are set up around it and its needs.

      That’s why I don’t understand why Tom sees EVs as a solution, rather than a major danger. To my eye, we face the choice of reconstructing our towns to radically reduce and socialize mechanized travel, or attempting to use the infrastructure we’ve got via EVs. I think the latter effort would be a case of letting Jevons’ Paradox lead us further into the maw of the Energy Trap. We can make the cars-first system last another few decades via marginally improving its efficiency. Or we can face up to its inherently wild mis-allocation of scarce resources. 3,000-pound, 95 percent idle machines make very poor substitutes for sustainable alternatives, regardless of fuel sources.

      We may not get two chances at this, either.

      • Hmm…. we are going to reconstruct our cities? And the cost of materials and energy for doing that is…..? I agree with the philosophy Michael, but I can´t see anybody redeveloping cities outside of the current ongoing rates of renewal or redevelopment. New build can work toward your goal, but actually has to fit in with the existing infrastructure and systems. Fitting EVs into cities is relatively easyin comparison.

  7. I believe that the good ole lithium iron phosphate battery coupled with GaAs Fresnel arrays are the most efficient route. Most these parts HAVE to be machine mass produced, to justify covering many thousands of square kilometers, putting it into the “harder” category. And I assume that since lithium and gallium are more abundant than lead, that it is doable on a wide enough scale to power humanity’s electrical and transport. Bulkier flow batteries should be able to handle grid storage.
    I would rather have lithium mining than coal mining, being that we can recycle lithium.
    Gallium, the metal that “melts in your hands” is too rare to be used directly as a flat panel, hence the need for concentrating Fresnel arrays. These type of cells are impervious to radiation (as NASA proves) and achieve close to twice the efficiency of what silicon has to offer (if limited to just a single junction). They also do not lose voltage as they get hot!
    I believe that geopolitical concerns over diminishing oil ought to “demand” a global network of HVDC lines necessary to utilize solar in a practical and obviously very large scale.
    Imagine all the jobs created (no bulldozing necessary)!
    Another reason to go “all out” for GaAs is that “normal” panels convert a lot of light into infrared, a no-no at some point of massive deployment. I believe that the much higher temps at the focus converts less light into infrared (with more of it being converted to slightly higher wavelengths) and the fact that GaAs is twice as efficient, means we can deploy so much more, safely.

    Eventually, we should use at least 60% less energy per person due to the efficiency of a machine produced solid state grid. Electric vehicles, leds, better insulation, passive solar building siting, hydroponics within large three dimensional cities, etc must be part of the plan. The city itself must be designed around electric vehicles or “carpods”… cable climbing in all directions as well as negotiating the old fashioned way on so many levels.
    I realize, though, some sort of thorium reactor will have to be utilized on a large enough scale to continue with (the immense amount of power required to build) the exponentiation of solar and its installation jobs.

  8. Just a thought, but I think the chard would benefit from the addition of fossil fuels, even if they all score 7/8. I think it helps visually point out the gap between where we are and where we need to be. Perhaps you might have two charts, one showing all energy sources (that you cover) and the other showing non-ff options. Like I said, just a thought. Super series.

    • Okay, you’re right: it’s worth the extra effort. Once I got over wondering what chard has to do with this, besides being a part of my diet… I put a chart in for fossil fuels.

  9. “Our success at managing the transition away from fossil fuels while maintaining our current standard of living is far from guaranteed.”

    It should not even be a goal. Our goal should be (and, I personally believe, should always have been) increasing quality of life. Standard of living is an economic construct that is basically a measure of what we consume (read, destroy). Maximizing consumption/destruction on a finite planet is neither sustainable or wise, yet that is the path we collectively chose.

    I see little likelihood that we can maintain our existing standard or living (at least in western industrialized societies). Indeed, there seems to be a general perception among the middle that standard of living is already falling, with an increasing expectation that the situation will deteriorate for future generations… that future generations will not experience the American Dream of having a higher standard of living than their parents. Even absent energy issues, economic and social issues (e.g., globalization, income inequality, etc.) are likely to continue to put downward pressure on this metric.

    The thing is that it seems almost inconceivable that those with high standards of living (and Americans in particular) will in any way be willing to voluntarily see these reduced. Indeed, the constant drumbeat of media stories regarding the increasing desperation of the middle class would seem to support this view. It’s hard to imagine the social/economic/political impact of the reduction in standard of living implied by this chart. Or, maybe it’s not.

    As long as we measure our “success” based on metrics such as standard of living, I think it is unlikely that we will ever be proactive relative to the predicaments we face. I think our only shot at proactive responses (a bit of an oxymoron, but you know what I mean 😉 is if we as a nation (species?) can convert our value systems (and then our societal systems) to target quality of life, and if we can do this before circumstances, nature and physics paint more red on your list.

    • I personally agree, and have shifted my lifestyle to use far less energy (more to come on this topic). I am aware that if most of us took such an approach, we could totally avoid the collapse scenario I fear. Indeed, values need to change, and quality (rather than quantity) of life can even improve in the process. How to encourage this trend? For me, the first step was realizing the tough spot we’re in trying to keep going the way we have. May not be practical/possible. Let’s design our own future, rather than having Mother Nature design one for us we don’t like as much…

      • We’ve basically more than halved our energy use at home:

        and we’re not suffering. We are having to make unexpected second-order adjustments such as dealing with humidity now that uncontrolled ventilation has gone down a bit. But we’re not in sack-cloth and ashes.

        (And we plonked PV on the roof to go carbon-negative for primary energy: I’m a big fan of PV’s low-maintenance and urban-friendliness!)



    • Personally, I think the best hope is forming a movement of people who make reconstruction a political demand, and find some way to inject that demand into the system before catastrophe arrives. The only way I see personal examples being effective is after some kind of major collapse phenomenon. Before that, the power and momentum of the corporate media and corporate-owned politics (which includes both Democrats and Republicans) is too great to allow the examples to be visible and a topic of discussion. Also, let’s be honest — it almost always takes time and higher education to be able to see the issues clearly enough to feel personally moved to serious action.

      • “Green” party is kind of vague and sounds ideological and is tied up with other issues. I wonder if a Sustainable Party, with platform policies geared toward 1000 year timespans, might get more traction. After all, your opponents are suddenly Unsustainable. 🙂

        • I’d like to see a no-growth party. Not one of the political parties about today carries that as a central theme. And for good reason. Political suicide, given prevailing attitudes.

          • I like “Progressive Survival Party.”

            I’m not convinced it’s political suicide, so much as politically forbidden.

            Of course, the fact that we don’t have proportional representation also means any new party has to be born huge in order to stand any chance of sending anybody to Congress.

          • At the risk of being accused of wordplay, I think a better term than “no growth [economy or party]” is “steady state”.

            Not only is it more politicially acceptable, it is actually a better description of what we are trying to achieve.

            Ask any small business owner if they would prefer the risk of shooting for growth compared to a steady state.
            Once you know what the “steady state” is, it is much easier to plan for it, and achieve it, be it energy, food, etc.

    • A book published in Australia in 1981 called, “Living Better with Less” and subtitled, “An end to ‘growthmania’, how to cut waste and improve our lives.” was one of the first publications I read that embodied these ideas.

      It’s a bit hard to get hold of now but the ideas are still valid and current. One interesting point in the book (that has been re-inforced over the years personally by further research) was that the “Standard of Living”/”Quality of Life” has not materially improved since the early 1970’s even though energy consumption per person has skyrocketed.

      Sure, we have more toys and interesting tools, and we have been able to cure a few more serious diseases, etc. but our health and happiness has not changed substantially since then.

      So it really make you wonder what our goals are or have been over the last 40 years.

  10. Transuranic waste may be nasty for some uranium breeders, but the IFR, with on-site fuel reprocessing, burns most of it up. Fast neutrons do that pretty efficiently. The reprocessing uses a technology that doesn’t separate plutonium from other transuranics, so it never produces bomb-grade material.

    Thorium breeders, in the form of molten salt reactors, don’t use sodium coolant. The salts they use for fuel and coolant are pretty inert, chemically. (This doesn’t change the point that significant development is still required.)

    But sodium is used as a coolant in the IFR. Advocates claim that sodium is used successfully in industry, and can be managed safely without difficulty. I suspect it will be a problem for public acceptance, when opponents show videos of sodium in water.

    I think thorium has more potential for public acceptance, since it’s so different from conventional nuclear, and has easily-understood safety advantages. I’ve had a lot of success advocating liquid thorium reactors to people who are otherwise strongly anti-nuclear.

  11. One big thing you also ignored is how geographical location can really screw up anything that uses direct solar energy in some way (PV, thermal, heating, photosynthesis, biofuel). These get more and more useless the closer you get to poles. I’d dare to say here in Estonia I should reduce them by at least one point (abundance), if not two (efficiency).

    While I’ve read every single article I haven’t read all the comments. Have you ever calculated how big is the energy loss for transporting electricity over great distances? I mean how long power cables can you make before losses become too big to make sense?

    • If your point is that it’s even harder than my matrix suggests (due to site variations), then all the more reason to be alarmed that our menu isn’t very satisfying. That said, solar is often sold short for higher latitudes. The yearly take can be impressively high for places you would think are terrible. But that statement doesn’t help much without long-term storage.

  12. [comment shortened by moderator]

    I was surprised that your matrix did not include a column for power or energy density. You seemed to have used the term compactness in a manner analogous to power density. Whatever we call it, this parameter is related to the energy return on investment for systems in which fuel abundance is not an issue.

    […]Others (see below) have done such an analysis and come up with significantly less resource use per Joule delivered for conventional 40 year old LWR designs than either solar PV or solar thermal, even while neglecting energy storage considerations. And we can do better. Advanced burner and breeder reactor designs using liquid metal cooling, seal-less electromagnetic pumps, supercritical CO2 secondary sides, pool reactor containment geometry, and passive emergency core cooling are significantly safer and more compact.

    Upon what basis do you claim that breeder reactor transuranic wastes are more nasty? My understanding is that breeder reactor transuranic waste products pose much less long term hazard than existing commercial reactor waste streams, since the half-life is significantly shorter. Please see below link, section 3.2:

    Because nuclear energy issues are so complex, with many choices to be made for a reactor design and fuel cycle, it is possible to highlight certain choices to suggest that nuclear power is not a viable option. I believe that by neglecting power density, your ranking system treats nuclear unfairly. In a previous post on energy “cubes,” you represented nuclear fuel requirements as the amount of crust required based on an average abundance of uranium. Why not treat fossil fuel and mineral resources in the same manner?

    • Power density and reliability of the production system affects the investment (and implicit energy expenditure) needed for the requisite physical plant per unit energy delivered per year. Likewise the energy density of the fuel source affects the amount of energy that must be expended throughout the production cycle (mining, transportation, waste disposal).

      On these scores, nuclear power is head and shoulders above all the other options. Power density in the core of a molten-salt reactor, for instance, is measured in *megawatts* per litre. Likewise, one person with a shovel could theoretically dig up enough thorium in an afternoon to supply all the energy needs for that person’s lifetime.

      These factors (power / energy density / controllability) must have a significant bearing on our ability to escape the energy trap. It is for that reason I believe it will be a lot easier to escape the trap with a full-on embrace of the full spectrum of advanced nuclear technologies than would be the case using weak, diffuse and intermittent renewables.

      • Nuclear power plants are not dramatically smaller (in area) than similar sized coal ones. And if you add in whatever is needed for proper disposal/storage/whatever of the waste, the footprint is bigger still.

        For real power density – power per square or cubic metre of the system it is hard to beat gas turbines, and nukes certainly don’t.

        But all that said, does the density really matter that much? If a coal plant takes 10ha and a nuke takes 5, or even one, does it matter if the nuke plant is twice the cost to build and operate?

  13. A fine summary, I just have 2 things to add:

    Using Ocean Thermal to produce electricity is similar to using nuclear fission to heat your house. The value of the electricity directly produced pales in comparison to the potential for growing seafood or oil algae. Perhaps a better example is the Aswan dam in Egypt. One drawback is that we don’t know what the negative consequences might be. Also, unlike tidal or geothermal which are impractical at a backyard scale, ocean thermal is completely impossible (assuming you want a positive EROEI) at anything less than a massive scale, due to the resistance to pumping being inversely proportional to the cross sectional area of the pipe used.

    My other main comment is the I think Biofuel – Wood deserves its own row. Abundance is merely potent, acceptance may be a problem, and efficiency is not the greatest, although using coppicing techniques beats the pants off algae and crops. But difficulty is low to moderate, depending on efficiency, and the technology has been demonstrated even for transportation decades ago. It is almost self-storing so intermittency is no problem. Direct heat is trivial, and electricity through a steam engine is not difficult. And it is very much a backyard technology.

    • We already use enough wood. I will hate the day cellulostic biofuels technology advances to the point of converting the forests (and soil replenishing “scraps”) into liquid fuels. Go electric “pod cars” that also attach to cables, vertically too.

    • That’s kind of an interesting idea. Biofuel/Algae with Ocean Thermal added on just as a bonus.

      We would get greens in the essential categories of “abundance,” “intermiitency,” “electricity,” “heat,” “transport,” and “acceptance.”

      “Difficulty” is yellow. Still have to solve the gunk/disease and access/maintenance problems.

      “Demonstrated” is red, but probably should be yellow, since they have built small scale pilot ocean thermal plants.

      “Backyard” and “efficiency” are red, but those categories should probably be given the lowest priority anyway.

      Another point in favor of Ocean Thermal is access to the cold sink of the deep water, which remains cool even after it has been used for electricity generation. Efficient air conditioning and refrigeration are valuable in the tropical locations where ocean thermal plants would be sited.

      A source of electricity, heat, liquid fuel, air conditioning and refrigeration that is abundant, non-intermittent, and accepted. The primary downside is a moderate difficulty that requires additional R&D. It is also not applicable to backyard implementation and is thermodynamically inefficient, but those two factors are of only academic interest to most people.

      Now we just need to find something to do with all the extra electricity. Build it and maybe people will come. Or maybe use it to fight ocean acidification in exchange for offset credits of some sort.

  14. Regarding algae, what’s the nutrient source for algae growth? What about nitrates? Can they really grow on just water, sunlight and CO2!?!

    • Algae needs nutrients of course. Cyanobacteria can fixate nitrogen from the atmosphere, but other than that they all need their building blocks present in absorbable form. And of course, it is the scarcest resource available in relation to need that controls how much production you’ll get out of the system (Liebigs law). Resources in abundance may be absorbed above the algaes current need, but will not result in further growth if an other resource is lacking. In almost all cases this runs down to a need for fertilizing the crop; which can be done by an initial fertilizing and then recycling dead algae to provide for the next generations nutrient needs, but a too closely tied circle here will lead to pathogen buildup and loss of efficiency (now the limiting factor is rate of disease in the culture rather than nutrient availability- Liebig strikes again).

  15. Thank you for an interesting summary! A couple of comments:

    – I find not putting solar PV in the “high-tech” category for “demonstrated” a bit optimistic.
    – The russian BN-600 sodium fast breeder reactor has been in operation for 30 years with an excellent service record. Is a better proof than this on the maturity of the technology needed? The other steps required to close the fuel cycle have been commercially proven for years as well.
    – Proliferation is not necessarily an issue for fast breeders. The IFR-concept takes efficient measures to prevent it for instance.
    – I would put a yellow mark in the “demonstrated” column for the thorium breeder. A lot of work was done in the 60’s and 70’s and the technology has been more or less fully demonstrated. Or do you think thorium breeders are as far off as fusion?
    – Fast and thorium breeders are in the same efficiency category as solar PV even though they provide high temperature process heat and a ~45% conversion efficiency. Solar PV, on the other hand, can deliver a 15 % efficiency and only produce heat via electricity. I find this a bit misleading…the span seems a bit too great.
    – I assume that more or less all geothermal plants are CHP sites, so a green box in the “electricity” column is perhaps more accurate.
    – All in all, I find the summary a bit biased towards solar in general. One could for instance argue that some columns are more important than others and would deserve a weighted score.

    But, as you say, whose matrix would be totally subjective?

  16. Hi Tom

    Your “marathon” efforts at assessing these alternatives is to be greatly applauded!

    I’m not sure if anyone else has referenced Richard Heinberg before, but certainly I have found his work diligent and balanced. This report from about two and a half years ago gives a thorough account of alternative sources using ten key criteria (incl. cost, scale, reliability, EROEI) :

    I’ll need to digest your assessment with his more thoroughly over the coming days, but I think that you both net out at a similar conclusion:

    1) There is no single energy source that can fully / adequately replace fossil fuels
    2) A combination of alternative sources will help us (e.g. solar PV, solar concentration and wind), but we will have to adapt to declining overall energy levels (owing to declining net energy)
    3) Conservation is key (i.e. stop clamouring for supply side solutions and carefully manage demand)

  17. For your thorium reactor choice, check out LFTR as an alternative. You could probably change atleast one of those red squares (possibly 2).

  18. This box should be yellow; that shouldn’t be red. Don’t make me turn this car around!

    My matrix is not authoritative, set in stone, free of subjectivity, etc. But while diddling around might allow nuclear enthusiasts to triumph over solar enthusiasts, the main conclusions do not change. Getting lost in the details and advocating pet fancies just helps obscure the fact that we’ll have a very difficult time replacing fossil fuels, and who really cares which of the myriad methods for making electricity prevails?

    • “and who really cares which of the myriad methods for making electricity prevails?”

      All of us – because we have to IMPLEMENT one of them which will probably require supporting policy.

      Why did you leave out ‘economics’? It’s largely what’s bought us to where we are today. If you don’t give it a separate column I think it needs to be intergrated into a mix of ‘easy’ and ‘acceptance’… and solarPV loses some points (it’s not easy to make it as cheap as coal or natural gas… and customers aren’t that keen on paying the significant premium required by the current solution (even if PV is becoming cheaper it’s still not CHEAP and it gets more expensive once the associated storage costs are factored in).

      • [edited]

        We don’t have to implement [just] one of them. We can implement whichever combinations of them work in each country. [Rather than] binary either-or thinking – the best guess is that some combinations of the top ten will be used.

        Economics. My first thought on looking at the chart was the same as yours – where is cost?

        But Tom has included cost indirectly, in the ‘Backyard’ and ‘Demonstrated’ columns. Anything green in Backyard has a low threshold for investment requirement. So many, many people can try it out and refine it. This was vital for getting windmills, water mills, steam engines and internal combustion engines into general use.

        Solar heat and biofuels win big here, and wind wins something. These technologies have the lowest investment threshold – investment by their users, that is. The green in Backyard for Solar PV compensates for its relatively high per-unit cost (once storage is included). This explains why these alternatives are seeing the most interest and investment.

        Yellow or red in the Demonstrated column means “many billions of dollars of research required”. That cost will have to be repaid by users of the technology. With a yellow or red in Backyard as well, R&D will be slow and politicised: subject to the Energy Trap.

    • “…and who really cares which of the myriad methods for making electricity prevails?”

      Well, I do think that a great deal of people cares. If not, they should. If the path taken turns out to be wrong, it will be far more difficult to “turn the car around” once it has gathered momentum.

    • I think he simply meant there are many ways to generate electricity so its not near as big of a problem as things like transportation.

      In the general scheme:
      Electricity –> Easy
      Liquid fuels for Transporation –> Hard

      • You think? I don’t really see it that way. Getting a solution that delivers everything we want for electricity is actually really hard (low emissions, abundant, cost competitive, reliable).

        Whereas providing an energy carrier suitable for transport applications is relatively easy if you assume an abundant cheap supply of electricity (hydrogen through electrolysis of water used to create kerosene, diesel, methane, ammonia; electric trains, electric cars).

        • “…if you assume an abundant cheap supply of electricity…”
          “…a solution that delivers everything we want for electricity is actually really hard…”

          That really makes the comparison become;

          Electricity –> Hard
          Liquid fuels for Transporation –> Even Harder

  19. Hi Tom,
    Thanks for posting all the articles and responses…
    Solar, which I am really fond of, will take up to three years just for the EROEI. So, if we were to build 10,000 sq km, it could take the power of 1/5th the installation just to double capacity in thirty years, in order for solar to slowly grow on its own, assuming 30 year lifespan.
    However, with GaAs concentrated Fresnel arrays, I believe it would only take 6 months to get EROEI. With that, it seems that same fraction could literally expand itself by 10 times in 30 years.
    Even though that seems possible, I care about which tech is used in the interim period between now and the oil depletion. Fossil fuels are needed to power solar production (because no one is really going to “set aside” x amount of solar to power its own growth).
    Therefore, it would be nice if all the LFTR advocates get their way, as to make sure we can continue to power a massive solar electric infra. After reading about it, I realize it’s not as easy as it’s all made out to be, but at least it doesn’t take so much FF’s to build.
    So, one may ask “If LFTR, why solar, too?”, to which I would reply “besides being backyard friendly and creating a challenge to build global power line networks, solar will give humanity enough install jobs to (hopefully) adjust to a machine economy”.
    The far greater concentration of energy from (a safer) nuclear will also be needed to build huge multi-level cities designed around mini electric cars that travel vertically and within many levels. These cities must also be designed to accommodate a gradual but eventual complete loss of jobs, as the machine economy will do anyways…

  20. Even if I could be categorized as a “nuclear enthousiast”, I would like to point out that the “Heat” category may be too broad. Some significant industrial processes require very high heat, say above 1300 K (, and the materials to handle and transfer such heat in a nuclear reactor are not there to the best of my knowledge. It means that it would require either inverted heat pump (I.e. using mechanical energy to heat the coolant at a higher temperature than at the exit of the reactor) or use nuclear power to synthesize organic compounds (such as Syngas) that can be burnt after. In both case, it will affect the efficiency of the whole process.

  21. Two comments :
    You say for the Uranium Breeder : “…the trans-uranic radioactive waste from this option is nastier than for the conventional cousin”. Actually it is the contrary : thermal neutrons generate more nasty minor actinides like Curium than fast neutrons, the worst for that matter being the use of Mox fuel that goes through two campaign of irradiation in a core. Fast reactors can indeed be minor actinide waste burners.

    Regarding Thorium you mention the “new” technical challenges of “liquid sodium”. I suppose you meant “liquid fluoride salt” ?

  22. Can we really call renewable energy renewable?

    Something i have difficulty grasping is the long term consequences of EROEI for the various new energy sources.
    If we accept that, at some point in the future, fossil fuels will run out, or at least will become economically and technically unviable, then how will we manufacture these new energy sources when that eventually happens?

    For example, to manufacture a solar panel requires large amounts of heat and energy. I don’t know exactly how many Btu of energy it requires but i imagine it to be considerable if you count all the energy inputs to take it from the raw materials in the ground to a shiny solar panel on your roof.
    I do know that currently most of that energy comes from fossil fuels but, again, i don’t know how many barrels of oil or cubic metres of gas it requires to produce a MW of solar power.

    I also have a hard time understanding how a solar panel will produce enough energy to produce another solar panel, again, considering all the energy inputs required to manufacture it.

    If we accept that cheap and easily accessible fossil fuels are limited then if we are going to transition to alternative sources of energy we must build capacity now whilst we still have the cheap and easy fossil fuel resources available.

    • This is well known and has been studied by many. The answer is that currently a solar panel replaces the energy it took to produce it (including frame, packaging, the whole ball of wax) within 3–4 years. Lifetime of 30–40 years means EROEI around 10:1. See for an example.

  23. Holy guacamole!

    That’s by far the best summary I’ve ever read about energy sources.
    Thanks a bunch, this will be my default go-to reference for techno-optimists.


  24. Thanks for this great article!

    First I’d like to answer one of your questions:
    “I do not know if examples abound of people having tried this for the purpose of providing heat in arbitrary (not geologically hot) areas.”
    The Netherlands is actively deploying this technique in some areas and it’s not particularly geologically hot. Sevem holes have been sunk so far. Most of these are to provide relatively low temperature heat for use in greenhouses. Many more projects are planned.
    I have some sources but they’re Dutch. Maybe you can make sense of it with google translate?
    The Dutch wikipedia article on goethermal heat:
    And the Platform for Geothermics:

    Second you seemed to have completely missed one important renewable source which has been in use around the globe ever since man first learned to make fire:
    Biomass (and the direct firing of it)
    – It’s not abundant, but not niche either
    – It’s very easy
    – It’s available on demand and easy to store (easier than liquids even)
    – It’s demonstrated
    – Electricity via firing a boiler or gasification and an ICE
    – Heat is easy
    – Transport via gasification and an ICE but this would be a yellow
    – It’s accepted in most places and with the right technology it can be acceptable everywhere
    – Very backyard suitable
    – Very efficiënt for heat 80-90% with no-tech, maybe 20% for electricity and transport (not so efficiënt if you view it as a proxy for solar)
    I think this one scores an 8 or a 9. That’s equal or better than all the fossil fuels.

    • I count 7. But yes, firewood and the like would have been a worthwhile addition. There is a reason it was a primary energy source for so long.

      • Yes, but if we converted to mass consumption of firewood then I think that the resource would turn out not to be abundant for long. This has happened in many cultures in the past (think Easter Island) and is happening now in East Timor.

        The subsidies on kerosene were stopped when the country gained independence and is now very unaffordable for most households. So people have reverted to wood for cooking etc. The impact on the forests and woodlands has been devastating and the country is being rapidly deforested with all the ecological impacts that ensue . It is completely unsustainable but nobody has a politically acceptable solution.

        • There’s more to biomass than wood.
          There’s also a lot way to use wood more effciëntly.
          Personally I see wood working in combination with passiv house insulation and solar heating. Wood is for those days that (buffered) solar heat isn’t enough.
          It could also be use to generate power on demand and fill in the last gaps we can’t fill with all other technologies.

          Moreover East-Timor isn’t exactly a case of sustainable forest management. There are plenty of cases of sustainable forest management. And the wood needed to cook on an open fire is a lot. You can easily heat a very large building with such quantities.

          And remember that I never said that would would be _the_ solution, rather part of the solution.

          • You’re right, it is not sustainable in East Timor (and in many other places around the world) but there are few current viable alternatives. Higher efficiencies would make some difference but the question remains, “How much can it contribute in a sustainable way?”.

            It’s interesting to note that one of the first major energy crises in the Western World was in England (and Europe) due to the unsustainable use of wood. Much of England’s and Europe’s prime forests were either destroyed or in danger of disappearing in the 1600’s until people developed coal as an alternative fuel source (and also started to strip the “New World” of it’s resources).

            Moving back to wood, and other biomass, resources, particularly with the much larger population pressures we have now, will be extremely difficult.

  25. Thanks for the wonderful series. Could you, however, explain where solar thermal produces cost-competitive energy? Having scanned through fair amount of literature on these things I have been under the impression that these things are NEVER build without massive subsidies one way or another. Also, for low energy density intermittent sources I think there are physics reasons to doubt that costs will drop low enough to be tolerable (we spend around 10% of GDP on energy already. USA spends on education 5.7%, for example). Reasons include: 1) low density implies large areas of construction…more work that is 2) Most likely higher material requirements (wind power requires about an order of magnitude more concrete than typical power plants) 3) harder to protect the plant from the elements. They are outdoors by definition–>> shorter lifetime or more maintenance 4) Transmission must be designed for peak production, but the cables would be mostly empty due top intermittency. 5) Solar irradiance has very large seasonal variation. Consumption might have an opposite variation so that demand peaks in the winter.

    • Do any of the alternatives in my chart get developed without subsidies? The economics of most of the items in the list are frightful. Hydro is cheap, and wind is not so bad. The cost and difficulty of post-fossil energy suggests to me that we’ll be changing our expectations and lifestyle in the future.

      • Well, wind IS pretty bad if you aim to provide the kind of electricity that the society uses. If all kWhs all defined equal then it is not extremely horrible, but all kWhs are not equal. The one that is produced when needed is valuable and the one not produced when needed is of negative worth.

        All energy sources require some support for development and, often more crucially, political framework where they are allowed to compete, but that is different thing from building the whole edifice of energy production on subsidies.Also, the scales of required subsidies are very different. In case of nuclear power lots of the additional costs are due to political and regulatory uncertainties and not technical issues. They can change when ever people so decide. The issues adding to costs of intermittent sources will not go away, no matter what people wish. I am personally quite confident that IF political risk is removed, NPPs are serially build, and they are allowed to evolve and
        traverse their learning curves that nuclear power can produce energy at a lower cost than fossil fuels today. This is not too hard because they are already cost competitive or nearly cost competitive in many places.

        Moving back towards preindustrial societies is an active choice with huge number of negative consequences and this shouldn’t be done if there are ways to avoid it. Just not getting a warm and fuzzy feeling about nuclear power is not a very good reason for this. Costs matter hugely and I for one rather live in a society that spends as little as possible on energy and uses the resources thus saved on education, health care, social security, pensions, development aid, environment etc. etc.

        Quote: “A number of plants are already in operation, producing cost-competitive electricity—and heat if anyone cares.” Here you do seem to suggest that CST doesn’t require subsidies.

      • “The cost and difficulty of post-fossil energy suggests to me that we’ll be changing our expectations and lifestyle in the future.”
        Please emphasize this more. People seem to think that because they grew up in a comfortable middle-class environment then it is certain to continue forever. A very good life can be lived while using 2 kWh per day and driving very little. This might be considered great wealth in 50 years.

    • Fossil fuel’s been built with lots of subsidies as well, like the freedom to spew its wastes into the air. As for tolerating costs, well, when the fossil fuels run out, you’ll tolerate what you can get…

    • Solar thermal produces cost competitive energy on the roof of many of my neighbours; cheap, simple, works like a charm.

  26. I lived off the grid for 30 years, the first ten without electricity. I cooked and heated with wood. For 20 years I got my electricity by charging a set of batteries with photovoltaics and wind. At no time was I not a part of the fossil fuel supply system – from the wood cook stove I had built in 1935, to the solar panels, the wind generator, the batteries, the chain saw and on and on and on.
    Solar and wind, energy capturing devices are not alternative energy sources. They are extensions of the fossil fuel supply system. There is an illusion of looking at the trees and not the forest in the “Renewable” energy world. Not seeing the systems, the massive machines, the fossil fuel uses and the environmental degradation that create the devices to capture the sun, wind and biofuels allows myopia and false claims of renewable, clean, green and sustainable.

    Energy Return on Energy Invested (ERoEI) is only a part of the equation. There is a massive infrastructure of mining, processing, manufacturing, fabricating, installation, transportation and the associated environmental assaults. Each of these processes and machines may only add a miniscule amount of energy to the final component of solar or wind devices yet the devices cannot arise without them. There would be no devices with out this infrastructure.

    How else would we do it? There is always the old way. Who of us will go down in the mine first?
    A story in pictures and diagrams:
    From Machines making machines making machines

    • Obviously we will build our alternative energy infrastructure with the dominant energy source at hand. So there is little intrinsic conflict in the fact that our current alternatives have utilized fossil fuels. A more important question is whether those energy inputs are substitutable. If a solar panel requires electricity and heat to fabricate, renewables can do that. As long as EROEI is positive, and we cover our bases (mining, transport, etc. requirements) with renewable sources, I’m not frightened by this alone. Not to minimize the difficulty/hardship of pulling it off. I think it is possible, but will we succeed?

      • This is a thorny question. My own quest started a couple of years back when I started wondering how much energy is required to produce the renewable gear? It looks like there is no way to know this until after fossil fuels are exhausted [which may take a long time on its own unless people awaken to climate change and voluntarily change]. It appears that there is positive return but things are really complex as John Weber indicates. Some people like to estimate EROEI using cost, but even if say without subsidies solar becomes profitable, it may be deceiving to use this to estimate EROEI as long as fossil energy has a high EROEI, there is no way to really separate the contribution of fossil energy using cost. There have been some attempts at creating pilot plants that is sort of a closed system to build renewable gear from renewable energy but this is not conclusive yet. My current thinking is that renewable energy is going to be an important transition technology but it is highly doubtful if it will survive after fossil fuels are exhausted. It would be good if you can investigate more in this area, I think a lot of R&D work should be going in this direction but I don’t see any national/international reputed labs [e.g NREL] doing anything with respect to this. We may be fooling ourselves.

        • [edited]

          “how much energy is required to produce the renewable gear? It looks like there is no way to know this until after fossil fuels are exhausted”

          If it takes 100 joules from oil to make some renewable gear, it takes 100 joules to make the renewable gear. Oil being cheap energy doesn’t change that it’s energy, and measurable. If you’ve been using 1 kilowatt of coal-fired electricity, you’ll need 1 kilowatt of solar electricity to replace that.

          • so do you know how much oil or coal is being used currently to make solar panels, including the energy to mine all the minerals, the electronics associated with it, battery, ship the panels, mount them on the roof, and maintain them. Is there any credible analysis on this anywhere? If you have this, then yes it would be possible to calculate the return. Intuitively it appears it will be a good positive return but there does not seem to be any rigorous analysis, probably because it is very difficult to do such analysis given the complexity of the technology and the associated supply chains [it is next to impossible to produce solar gear in a particular place until it has readily accessible all the ingredients to build them]. John Weber’s pictures will help anyone understand this very clearly in case it is a bit difficult to imagine.

          • Damien RS’s comment is debunked by John Weber’s link (a the top of this very thread).

            I wonder if that’s a record for rebuttal speed — before Damien’s comment was even written!

          • A bunch of photographs and pessimistic doomsaying constitute neither a rebuttal nor an argument. Where’s the math?

  27. and so the magic formula becomes

    Our Future = (mix of less potent energy sources) / (less people * less energy)

    Right, that’s the easy part! Now, let’s start expanding each of those terms….

  28. This study is not so much about energy as about the rather whimsical proposition that a fossil fuel-based civilization can be perpetuated by other means (it can’t). The main issue with oil depletion is how to continue to provide transportation (or to drastically reduce the need for transportation fuels by rapidly relocalizing the economy, banning the use of private cars for commuting, etc.). Before fossil fuels came into widespread use, the main forms of energy used in transportation were wind and fodder. Yet all I see above is discussions of converting wind to electricity, and no mention of fodder at all. The Norse Vikings died out because they wouldn’t eat fish. Contemporary Americans will die out because they refuse to get rid of their cars and to provide for their own needs locally.

    • Solar and nuclear can be used to replace (and even far surpass) this great fossil fueled age
      We surely have ALL the tech.
      By googling, I learned that it takes at most, 3 years to get EROEI for PV, about 6 months for solar thermal and wind, etc. Now, i must admit, the hard part is using fossil fuels, now, to build enough RE to expand on its own. Thus, if 1/5th of any concentrated GaAs Fresnel array field was to be used solely for its own growth, it would expand by TEN times in thirty years, assuming about 6 months until EROEI.
      Since that is so hard to do in this age of money based politics, at least we should (also) build thorium reactors because they were proven for a few years with… get this… just 1960’s technology!
      It is time to envision an age where people use less energy and still have more! Imagine what the city shall be built around, after all, we do NOT have an energy shortage, just a lack of collective focus.

      The cities should be built around the most efficient (and totally different) lifestyle. Gas guzzlers turn in to mini electric carpods that also transverse by vertical cable. 50 mile commutes turn into just a few miles at most. Florescent lighting is replaced by leds that will be 3 times as efficient (12 x Edison bulb). Large (and architecturally beautiful) buildings require far less heating and cooling.
      I believe that the energy problem is not as important as the “planning” problem as we already have the tech to build a massive and (almost) clean energy infrastructure.
      There is even the possibility of “machine printed” construction, furthering the reduction of energy requirements…

      • That all sounds fantastic, but unfortunately we can’t afford to replace our entire transport fleet and rebuild our cities at this stage in the game.
        I think the rules henceforth will be:
        1. adapt in place
        2. retrofit is the only available modification
        3. make do with less

        I think you’re dreaming if you envision a near- or medium-term future of shiny Jetson-like carpods and glistening skyscrapers covered in PV and wind turbines.

    • Nature seems to have left us a way out. Most of human civilization was powered by biomass, full stop. Bit of water for mills, bit of wind for sails, some peat for heating, but mostly current biomass, wood and food. Biomass apparently is generally 1% efficient at converting sunlight to itself; efficiency of converting biomass to heat is nearly 100%, to electricity I don’t know but let’s say 20%, to light I don’t know but let’s say pathetic. We also didn’t have bicycles or modern — even 19th century — mechanical ability, high quality steel parts, rotary instead of reciprocating motion, and all.

      Solar panels generate electricity at 15%, which can convert to heat at 100% or better (heat pumps), to light at much better than fires or candles, and of course is read to do work.

      History was sun-powered, the future may be sun-powered, but that doesn’t mean the future will resemble the past; we have various tricks now that not only did we not have, but nature hasn’t evolved either, starting with the ability to have 15x as much power from the available sunlight.

      And then there’s nuclear or deep geothermal or high kite power as possible backups, more resources the past and life never tapped.

    • [shortened by moderator]

      This study is not so much about energy as about the rather whimsical proposition that a fossil fuel-based civilization can be perpetuated by other means (it can’t).

      What is wrong with high-energy lifestyle? What is so wrong about wanting to perpetuate it? Why is it impossible?

      Both economic prosperity and lower birth rates correlate with higher energy use. Broadly based economic stability and sustainable populations around the world will lead to a more peaceful planet. Energy poverty will do just the opposite. Energy use in the service of our needs is a good thing.

      Developing-world energy use must rise significantly to bring the vast majority of humanity out of extreme poverty. World energy use needs to GO UP DRAMATICALLY to achieve this, while shrinking CO2 emissions.

      There is ONE sustainable solution for a problem of this scale: advanced nuclear power. […] A nuclear revolution is possible according to science and engineering facts with many different possible technology paths (fast neutron, slow neutron, water / liquid metal / molten salt / or gas cooled, liquid fuel, solid fuel, U-Pu breeder, Th-U breeder, etc.), but public attitudes and the politics must change first. Ignorance, misinformation and hostile politics is what truly stands in the way of an energy-rich, prosperous, sustainable and emissions-free future.

      I have kids and hope to have grandchildren. I don’t accept energy poverty and economic misery as the only possible outcome from the demise of fossil fuels in their future. We can do better than that.

      • “What is wrong with high-energy lifestyle?”
        Nothing. I think we can all agree that having access to energy is a Good Thing.
        “What is so wrong about wanting to perpetuate it?”
        Again, nothing wrong with that either.
        “Why is it impossible?”
        That’s what this blog is about. _Is_ it possible? So far the answer seems to be “no”. You seem to think that just because you want something it can be done, but the universe doesn’t care what you want.

        “…We can do better than that.”
        I really hope you’re right, but the signs so far aren’t encouraging.

  29. Couple comments from another blog on the costs of converting to renewable fertilizer, or higher electricity prices:
    “At 10 cents per kilowatt hour, a metric ton of electrolytic anhydrous ammonia would cost $1400 ($1200 of that paying for electricity). This is more than twice the current price of $590, but actually less than the $2187 (inflation-adjusted) that an American farmer would pay for the same nitrogen input in 1955. Even if we have to make nitrogen fertilizer without fossil fuels, it’s going to be a return to the mid 20th century in terms of prices rather than to the 19th century.”
    “For example, according to a note in the January 1947 edition of Life magazine, residential customers in the US paid an average of 3 1/3 cents per kilowatt hour, a tremendous drop from the original 1882 Edison plant price of 25 cents per kilowatt hour. Adjusting for inflation, 3 1/3 cents in 1947 would be 34 cents per kilowatt hour in 2011”

    “Renewable electricity looks expensive compared to recent Business as Usual. Compared to Business as Usual as recently and near as 1950s America, it’s surprisingly cheap. When the next doomer or Republican tells you that we’ll all live in mud huts when we can’t use cheap fossil fuels (either because fuels run out or environmental legislation stands in the way), ask them to estimate how expensive electricity was at the end of World War II and how much more expensive green electricity is today.”

  30. I note that nuclear enthusiasts (here and on the reddit thread) who are disappointed in how low my nuclear rankings ended up compared to solar have offered energy density as a reason why nuclear blows everything else out of the water. First let me point out that I don’t think of myself as anti-nuclear: I just don’t get very excited about it.

    It’s true that the energy density of nuclear material is millions of times higher than chemical energy, so one might argue that its efficiency should be off-scale (at least colored green). Sure, I see the attraction to energy density. But does this make a 1 GW nuclear plant one-millionth the volume of a similar-power coal plant? Does it make the cost one millionth? Technological ease? Cooling requirements? Is it one million times safer, or a million times more likely to be useful in your backyard? Is there a comparable volume of uranium or thorium available as exists in fossil fuels, so that nuclear resources dwarf the fossil fuel resources by millions? (Hint; all these answers are no, and in fact in many categories are worse than fossil fuels and other alternatives.)

    Nuclear energy density is cute, but it’s not a very useful metric when translating to practical considerations.

    • Tom, be honest – that’s a straw man you’re setting up. Who is arguing that a nuclear plant, because the fuel energy density is 1,000,000:1 over coal, means the plant will be 1,000,000 times less in energy or $ to build!???. Certainly not me, nor any other nuclear booster I’m aware of.

      Energy density does mean, however, that 30-40 tons of fuel for the LWR (2 orders of magnitude less efficient than possible), will produce 1GW of continuous electrical power for 1 year. Now how much coal has to mined, shipped to a coal plant to do the same (IIRC, ~3M tons)? How much energy do those 3M tons take to mine and transport? How much CO2 is released (IIRC 12M tons)? How much coal ash / sludge is left over with no safe disposal option?

      This might not be 1,000,000:1, but it is around 100,000: 1 in round numbers for current technology that’s ~1% efficient. Not bad in a future world of constrained fossil resources, where emissions must be cut dramatically for climate reasons.

      So, the plant costs won’t scale by the energy density ratio, but the fuel and waste streams certainly will, as borne out by facts (I can dig up exact numbers if so required to do the math).

      Plant costs will scale roughly with POWER density, however. Power density of a coal furnace certainly isn’t orders of magnitude different from a LWR reactor core, now is it? One wouldn’t expect the steam plant, generators, etc. to be much different either. But, we’re not talking about an energy trap to build plants with the material inputs to build along the lines of coal plants? An energy trap will happen if one modest coal plant has to be replaced by 2,000 2MW wind turbines + massive storage + supergrid, and / or millions of solar panels.

      • In part, I was reacting to this comment on another forum:

        Also, how is it that the nuclear options are getting moderate efficiency ratings? It is six orders of magnitude more energetic than fossil fuels.

        A number of comments on this forum also comment on the energy density attributes of nuclear. Furthermore, I sense a general fascination with the tiny volume of actual fuel needed to supply the reactor. My main point is not to let that overshadow the host of other practical concerns.

        So you’re right: no one claimed nuclear was a million times better in the categories I enumerated—and I didn’t mean to suggest that anyone did. But the construction was a useful way to illustrate how the phenomenal energy density fails to address most of the ranking categories in the matrix.

        • Tom,

          In stating that you are not anti-nuclear, perhaps you are trying to suggest that you are being fair and impartial by rating all nuclear options at 2 or below. If so, this is a self-assessment, and we humans tend to be bad at it. Which is one reason to talk, blog, argue, listen, and be flexible.

          You and many others seem to be missing the boat regarding waste streams. Existing nuclear waste is actually a vast potential resource, and it is very substantially contained. Nearly all fossil fuel waste is discarded into our atmosphere, where is causes a whole host of problems. I hope you will revise your matrix after taking a look at climate change.

          As we extract more energy from nuclear fuel, the resulting waste becomes less hazardous. Please follow the links you’ve received regarding advanced breeder and burner reactors. I would be interested in reading your reaction, as you currently seem to be misinformed about advanced nuclear fuel cycles.

          For remote installations, I am excited about solar. However, electricity is a luxury if one is off the grid to begin with. Most of us reside in an urban environment where electricity is an essential service.

          Thank you for your articles, and moderating this discussion. I was very impressed (9/10) by your galactic scale growth and nation sized battery articles. We seem to agree about the problems if not the solutions. Split wood and atoms, ride your bike, and push the pill!

          • Another resource I’d like to share is the book “Powerplant Technology” by M.M. El-Wakil. It includes detailed thermodynamic discussions, comparisons of thermal-fission, fast-breeder, geothermal, hydrocarbon, solar, wind, and ocean sources, energy storage and environmental considerations. Some time ago, I was fortunate enough to attend courses taught by the eloquent author.

          • To clarify, then, I am not someone who has ever been attracted to the “no more nukes” movement. I don’t think nuclear plants are inherently bad things. I think the degree to which public perception is negative is unjustified. So I claim I am not anti-nuclear. Sure, self deception is an old sport, but in this case I think I’m being accurate. I think some folks are just disappointed that I’m not more enthusiastic than I am.

            Keep in mind also that the numeric scheme is not to be taken too seriously. I called it boneheaded right there in the article. Different weightings and different emphasis and different categories will produce different results. Get out your crayons and make one you like…

          • 1) Tom is clearly being conservative, pessimistic of claims not fully demonstrated with commercial sales. Given his goals, this is perfectly reasonable, and should be familiar to any engineer.

            2) He’s also giving full weight to various social factors, not just technical ones. Fear of nuclear accidents, waste, and proliferation is a real thing that you can’t handwave away.

            It’s also not entirely irrational. It’s one thing to believe that engineers can make a safe nuclear power plant. It’s another thing to belief that political and corporate cultures will let engineers build as safely as they can, without cutting corners. Fukushima shows us that even one of the most advanced and cohesive societies in the world can’t guarantee that.

            Optimistically I can boost the breeder options up to 4 on his chart, leaving solar still in the lead. Ditto for geothermal depletion electricity, or enhanced geothermal to everyone else. Granted, an existing cost column might well change things! Though solar costs seem to be falling down, while nuclear plant costs seem to going up…

      • A comment above mentions “megawatts per liter!” as if this of profound importance.

        Fission fuel is dense compared to coal, but the mining impact may be similar, when the fissile metals are dispersed, vs. solid mountains of coal.

        • Could be, but definitely isn’t. In Canada we’re extracting ores whose richness is on the order of 20 percent, so rich they have to be diluted before going to a mill that was built before the new class of deposits, called unconformity deposits.

          Elsewhere, ores as low as 0.05 or so percent are still being mined, still able to compete, and this may not be surprising when you realize such an ore is ten times more energetic, in present-day reactors, than pure coal. Which, by the way, comes in seams, not mountains.

        • I think MWh/L is also a consideration as we approach Peak Water. Perhaps not the primary consideration though.

        • Pro thorium states that a ton of granite equals 50 tons of coal (if the thorium content is used in a LFTR). But such “extreme” measures would only be needed for quite awhile. The fertile material left over in the mountains of coal ash have over ten times the energy potential as the coal from which it came! There are also concentrated ores not to mention 3,200 tons of the metal buried in Nevada.

  31. Perhaps someone asked this in the responses–which I admit I only skimmed through quickly, but why did you not include methane from anerobic digesters as a liquid fuel source? We have lots of manure and waste which can be digested, and methane captured & refined. Waste heat can used to heat barns or greenhouses–or can turn a turbine to make electricity. Plus, the resulting fiber can be used as bedding for animals, back on the fields, or made into a peat substitute. Entire towns in Scandanavia have a “closed loop” that take the waste and run all public transport as well as many cars on the methane. It is a fuel source that is a “win-win” in my estimation, yet is barely mentioned by any experts. The technology is simple, relatively, and can even be used in one’s backyard–although not as efficiently and cleanly as in a well run large facility. Certainly demonstrated–not intermittent. Do you not include it because you don’t think we have enough waste to make it worthwhile? Just curious. Thanks.

  32. I think one thing about human nature we are not addressing well enough is that modern Westerners will not accept a forced voluntary reduction in their energy consumption or “freedom” to drive their cars wherever they want in the name of some higher goal of alleviating imminent Peak Oil, which most people don’t believe in anyways. It will be perceived as another “socialist conspiracy”. Therefore, the only way to reduce energy consumption in the current environment, without a major crash to wake people up, is to do so by substitution. The most effective way to do this is to push electric cars ASAP because they are arguably better than ICE’s.

    I don’t buy the argument that since it takes FF’s to make electric cars they aren’t a “solution”, because this is EXACTLY what we should be doing with our remaining FF’s — building out renewable infrastructure that will be able to accept alternative energy when the time arises. Doing ANYTHING today requires using FF’s. Does that mean we should do nothing? Just because it requires FF’s to make EV’s today doesn’t mean they couldn’t be made with renewably derived electricity and heat in the future. Let’s get the ball rolling today!

    Another point not often considered in the equation for solar PV is that the post-Peak Oil world is not going to be a nice place. With economic contraction will come rampant unemployment and desperation. The monetary system will collapse. Energy will be scarce and valuable. By placing an array of solar panels on your roof you are basically advertising to every criminal in your area that, “We have energy. We planned for the future and therefore we likely also have other resources too. Come get ’em”. Are you going to hire security guards to watch your roof when you go on holidays?

    • You’re reminding me why the peak oil phenomenon can scare the bejeezers out of me…

      I agree that if we’re going to make this transition work, we’d best devote a substantial fraction of our resources toward the problem now. The Energy Trap post offers one motivation as to why this is important.

    • How do we know what “human nature” is, let alone what people would want, if given real choices? Indeed, there is already proof that people want to do more about the environment (see the long-running data collected by NORC via the General Social Survey), even without an ounce of mainstream leadership on the topic.

      As for EV’s, how is trying to eke another decade or two from the present vastly too-large urban infrastructure a good idea? Using EVs to do that means we would have added yet another layer of uselessness to the system. What good will a network of suburban car-charging stations be in 100 years?

      Fortunately, EVs are a pipe dream within a pipe dream. Neither the batteries nor the electrical grid nor the spending power are there in anything close to sufficiency to render them a mass phenomenon.

      Transportation is our single biggest form of waste. Trying to make it marginally less wasteful, especially without being honest about the huge obstacles to doing so, is our single worst green delusion.

      • Sure, people want to do more for the environment, but I’ve found that enthusiasm wanes if it means cutting back on lifestyles and profit.

        The only other future option for transport besides EV’s is bicycles, elephants, donkeys, slaves, or mass electric transportation like rail etc. (which I totally support but it’s not practical for a lot of commercial applications — how do you get food and goods or other large items to individual locations from train stations?)

        I say, if we are currently building X million cars a year today, why not do everything we can to make as many of those EV’s as possible? If we have the spending power to buy X million ICE powered cars then we have the spending power to buy X million EV’s a year instead.

        People keep telling me the batteries aren’t there but I have yet to see any evidence of that. The battery in my Leaf is just fine. As to the electrical grid, I charge at night with a 1500 W charger, the same draw as one of those little portable heaters fed with a spindly little cord, which is about what the average house’s electrical consumption goes down by at night. Therefore, hardly any new electrical infrastructure would be required for an almost complete transition to EV’s if people charged at night — everyone already has multiple plugs in their houses. OK, maybe apartments might need to install some plugs… big deal.

        • How much does the battery in your Leaf cost?

          Apartments don’t necessarily even have *parking*. Where are their plugs supposed to go?

          “how do you get food and goods or other large items to individual locations from train stations?”

          Probably trucks that are EVs or running on synfuel. But the fact that there might be some essential niche EVs around doesn’t mean it’ll be sensible to convert all the private cars to EVs.

          • We can NOT continue to base planetary civilizations on fossil fuels, however, if “everything” was converted over to non fossil generated electric, then the biosphere should have no problem with just powering the trucking, aviation, and steel industries for the few decades longer that it takes ’till something totally unforeseen (like graphene) becomes deployed.

            There is no reason why ALL cars couldn’t be electric… other than the cause for mark up. The tech is there (search LiFePO4), the resources are available (lithium is slightly more abundant than lead), and ideas abound for a transition to personal rapid transit (search that too) which, if pursued as a long term goal, would effectively cut per person energy requirements by close to an order of magnitude. Cities could thus become “three dimensional”.
            We can not afford to continue to live in the past…
            Thus why base the future of energy on such?
            It is far easier to build a few more powerlines and “plugs” (and MSR’s, massive solar deployment, etc) than it is to reap the fruits of “be negative and do nothingness”.

  33. Kudos for a great post and a simple, yet clear weighting scheme. Although I concur with your overall assessment, perhaps you can add a column or two for “environmental externalities” (perhaps one for resource production and one for power generation)? In that case, oil and goal would probably come down to a 6 and gas to a 7 while solar PV might push up 1 and thermal 2.

    • I’d concur, regarding an environmental column, which I think is an absolute necessity, if we are not to repeat the mistakes of the past (which we will). We can’t assume that there will be no impact on the environment or that the particular energy source will not be limited by environmental impacts, in some way. Even if a source had green boxes all the way, if the hypothetical environmental impact/limits box is red, then it should not even be considered.

      I believe scientists are only now beginning to think of environmental limits (e.g. the effects of extracting energy from the wind), which is great but the need for such research is urgent now that we are desperately trying to think of alternative energy sources.

  34. [shortened by moderator]

    “You’re reminding me why the peak oil phenomenon can scare the bejeezers out of me…”

    […] Peak Oil fanatics are like kids competing to tell the scariest story at a camp fire. Resource stories always leave out the part where somebody comes up with a new and different way of doing things, and solves the problem, Remember we are using petroleum because whale oil was becoming too expensive.

    Second, I think you have overestimated the problems of nuclear power, and underestimated its abundance. What you call breeder reactors were purpose built machines for producing bomb making materials. The 4th generation reactors that can burn U238 or Th232, are not breeders in that sense. They are not theoretical machines either as working engineering prototypes have been built. In fact GE/Hitachi will take your order for an IFR that can burn U238.

    Further, the nature of proliferation risk is best illustrated by the current situation in Iran. They are pursuing Uranium enrichment, because it is easier and cheaper than using plutonium which is expensive to create, and very difficult to turn into a working bomb. If nuclear weapons were easy or cheap to create, somebody would have done so. The Iranians are demonstrating that it is very expensive and very difficult.


    Finally, you have repeatedly stated that solar pv produces a substantial fraction of its maximum capacity even in winter. “St. Louis, MO (my benchmark for average/median U.S. solar site) gets 69% of its yearly average in December.”

    First, comparing a month to the yearly average is not helpful. No proposed storage system will store enough in June to be able to supply requirements in December. […]

    Where I live in Ohio, we need energy in December even more than we need it in June. But, St. Louis, gets more sun than we do (I checked the NREL maps and charts at the website you so graciously linked), so we would need even more storage or we would have to build a system large enough to power us in December, which, given the vagaries of our weather would have to be Brobdingnagian.

    • It’s true that seasonal storage is a very difficult problem. The standard solution for PV is build the system to be adequate for December. Makes it more expensive (maybe not quite double compared to designing for yearly average), but it can totally be done. So this is different than saying “PV can’t work where I live.”

      Again, if you want your alternatives to to fossil fuels to also be cheap, be prepared for disappointment.

        • Except that cheap and easy are usually highly correlated. So maybe it should be:

          cheap/easy or sustainable. Pick one.

          More of a project stick.

    • “Resource stories always leave out the part where somebody comes up with a new and different way of doing things, and solves the problem, Remember we are using petroleum because whale oil was becoming too expensive.”

      The problem with blind faith in the ability of the market to solve all problems is that market dynamics always require abundant energy in order to be able to do “new and different things”. It is the driver of all. That’s the way the past has worked; the energy requirement was always satisfied, and that’s the environment that shaped our understanding of how the market works.

      We moved from whale oil to petroleum because we both ran out of whale oil and petroleum was better. Now, we are running out of petroleum but we have no better energy source to move onto, and even if we did, our infrastructure is wholly unprepared for the transition given the timeframe for oil depletion. I predict that we’ll begin to make synthetic oil out of natural gas and maybe coal, and this will buy us some time. But this will deplete those reserves much faster. Then what? Then throw in declining EROEI and things could go exponential quickly.

      The implication of all this is that the political, monetary, and economic environment will become increasingly hostile and turbulent, making the coordinated efforts that would be necessary to develop the alternative strategies less likely to happen. It is a very dangerous precipice we are walking along, with a lot of (IMHO) unjustified faith in magic and the ability of “the market” to solve the problems, because this is uncharted territory for economists. They never previously factored energy into their theories; it was always an unstated, implied, and misunderstood assumption baked into every chart.

  35. Tom,

    I love your posts but you should be aware that your table is a little hard on the 8% of males that are colorblind.

    Use the simulator at to get an idea of what it looks like to a colorblind person. You can use a little more blue in your green and change the saturations to make the colors more distinctive for everyone.

    Keep up the great work!


    • Good point. I like that vischeck site! I have often wondered if something I produce is discernible to R/G colorblind folks, and (with this obvious exception) often tune my work to not rely on R/G distinction.

      In any case, I made a different version:

      Now blue is the old green (adequate), yellow is still yellow, and I upped the red saturation a bit. Looks pretty discernible on vischeck.

      I also did the FF version, and put links in the main article to the alternates.

  36. You might consider digging a bit deeper in the IPCC and WWF scenarios on future renewable energy provision. They are slightly more optimistic than you are – and they have certainly done their math!

  37. I think supersonic trains are much preferable to airplanes for global transportation of both personel and goods. Trains do not need a transportable fuel source and electricity to power the trains can be generated throughout the world and the sun is always shining somewhere.

    Japan got it all figured out, their society uses lots of trains and I belive trains will become increasingly more important as energy scarcity increases.

    I think that we can make do with synthetic alcohole transportable energy and photovoltaic electric production to cover all our needs.

    But we also will need to reform farming, the way we are doing it now is by working against nature and eroding the soil and resources. I like to further explore permaculture and free-roaming cattle for our food production.

    • Supersonic trains would be pretty neat but also have no prototypes and would probably be expensive. You’re talking evacuated tunnels and such.

      High speed rail is current but is about half the speed of a jetliner which builds up over long distance, as does not being able to go in as straight lines as planes can. Plus of course, oceans.

  38. The method used which essentially ignores cost seems to me to have serious defects in its ability to make comparisons.
    So for instance solar pv is given as not being difficult, and super abundant.
    It is however extremely costly with anything remotely like present technology, especially since you have to do something about intermittency and storage, and so without radical revisions of present technology is not for practical purposes abundant, especially at high latitudes.

    Conventional fission is on the other hand given as being in relatively short supply, going as far as to give it a red on this account.
    We already know how to reprocess short of breeders though, and the problems with those were mainly about cost since uranium is so cheap , but even short of breeders the fuel could be used much more efficiently without nearly the technical progress needed to make solar pv practically as well as theoretically abundant.

    The cost for the raw uranium is around $0.003kwh.

    If we were prepared to pay 1 cent kwh then the supply of uranium and thorium, which can be burnt in conventional reactors, even excluding obtaining it from the sea which could be done at far less than that, would make conventional fission a super abundant source.

    The total cost of the energy with the uranium/thorium at 1 cent/kwh would still be far less than anything we are anywhere near being able to do with solar pv in almost all locations.

    It seems then to me that once any account at all of costs and the actual present state of the technologies are made then far from being niche even conventional nuclear fission with reprocessing is many times as abundant as the somewhat theoretical claims of solar pv.

    • I didn’t realize until this posting the degree to which nuclear and solar appear to be rival, but it comes up a lot. Fuel costs do not dominate nuclear, meaning that we can tolerate having to pay more. But to pass off conventional nuclear as super abundant and cheap does not mesh with my assessment (see post on nuclear fission) that even tripling the estimated world resource of uranium only allows a few decades of fuel if nuclear were used full-scale. I’m not proposing that nuclear be used full-scale, but this is a method for assessing its potential/availability. That’s why it’s red in the abundance column for me. Move to techniques that use uranium-238 or thorium, and the red goes away.

      • Tom, my objection is really that in order for solar pv to be practically as opposed to theoretically super abundant, then massive improvements in storage and the cost of generation have to be made, as you yourself have highlighted in some of your previous articles.
        It therefore seems artificial to break nuclear down between what we have to hand right now and any improvements whatsoever, even using technology which we know perfectly well how to do, for instance reprocessing, mining very lean ores at higher cost, and burning thorium in conventional reactors such as the CANDU and Westinghouse.

        Your comparisons for abundance do not therefore appear to me to be like for like.
        It will be a lot tougher and more technically challenging to counter the intermittency and storage issues of solar pv to make is a practically super abundant source, not to mention much more costly, than to up the efficiency of present nuclear burn.

        If you want instead to compare the use of solar pv to conventional nuclear at any affordable cost using present technology only, then solar pv is very much niche.

        • I am fine with my classifications. Solar is indeed super-abundant, in that it would not tax our resource allocation to collect as much as we demand. You are concentrating on the storage issue, which is why solar has the big red square on intermittency. I separated those things (nuclear is green on this front) for the matrix, but naturally they must be considered together (along with all the other factors) in a full assessment. If you want to apply more weight to the intermittency factor, then do so. Abundance in the matrix has a narrower definition than what you want to apply.

          Developments can happen on all fronts, and this matrix is not static as a result. The boxes are colored for today’s conditions. I could be correspondingly bullish about storage breakthroughs, which would boost solar’s viability considerably. But I tend to be skeptical about many of the blue-sky technofix scenarios—across the board.

          I’m going to exercise the option (explained in the discussion policy) to cut off the back-and-forth at this point. I’m simply overwhelmed with other tasks: inevitably, some may interpret as running away. I can’t help that, but I’m simply overtaxed (there’s just one of me, after all, and lots of comments). I think in this case, our points are clear.

  39. Many thanks both for your responses and the original thought and debate provoking article.
    Do have another look at the notion that you can only multiply effective uranium reserves by 2-3 times even with very large increases in prices though! – It just ain’t so! 🙂

  40. I am somewhat surprised that your assessment of ocean current energy seems to include only the huge pelagic currents like the Gulf Stream. I live in a small city right by the ocean. At the bottom of my street runs a current of 4 – 5 knots twice daily, over a shallow seabed. At 800X the density of air, the power available here is significant. Island countries like Britain have currents like this in abundance.

    I did do the math once, but cannot locate it. The equivalent was approximately a 130 mph wind.

    Agreed that there are corrosion and other issues to overcome, the basic technology is not much different from run-of-the-river hydro.

    • This is a tidal surge, and should be counted as tidal energy. Such phenomena tend to be constrained to be near shorelines, so not large area, and thus not adding up to terribly much resource.

  41. Re storage and transportation, a methanol rather than hydrogen economy has been suggested, with the advantage of recycling waste CO2. One paper I saw.

  42. Tom,

    I think the one concern I have from your nuclear assessment is your look at current advanced nuclear reactors. You mentioned very clearly in your previous post on nuclear fission that you had not studied the current modern reactors, like the LTRF, enough to make a full claim on their feasibility.

    I am curious to know with this new matrix, if you have had any time to brush up, and have come to any new conclusions?

    My main point of contention is that you state nuclear options like thorium are not abundant enough to be excited about. But a common thread I have read in (granted) pro-thorium sites is that high abundance of thorium + high energy conversion + ability to convert existing waste = an energy resource that could sustain our current levels for thousands of years.

    Does your math around these new reactors tell a different story? If so, I would love a follow up article from the previous one.

  43. Thank you for a thought-provoking series of postings. However, I have to say that your dismissal of space resources seems to have been premature. Here is the view of Professor John S. Lewis of the University of Arizona’s Lunar and Planetary Laboratory: “In my view, returning lunar or asteroidal materials to a factory at HEEO [highly eccentric Earth orbit] gives us enormous leverage. Each ton launched from Earth can provide us with 100 tons of asteroidal metals at HEEO for use in SPS [solar power satellite] construction. The challenge of _how_ to use that powerful leverage for the benefit of humankind is simply an intelligence test. If we pass the test, we will be able to provide unlimited amounts of energy to Earth at costs below current energy costs, without further fossil-fuel consumption or nuclear-power-plant construction. If we flunk the test, we get to freeze in the dark.” (John S. Lewis, _Mining the Sky_, Addison-Wesley, 1996, p.133.) I look forward to reading your comments on this astronautical classic, as well as on Professor Gerard K. O’Neill’s _The High Frontier_ (3rd edn, 2000), which also makes the case for solar power satellites.

    Oxford, UK

  44. Tom,

    This overall result seems highly unrealistic to me: fossil fuels in general, and oil in particular, appeared to be great in their day, but they are much more expensive than they appear (IOW, they have large externalities) and they can and should be replaced ASAP.

    So, what’s wrong with the matrix?

    First, green house gas emissions shouldn’t be a trivial afterthought. The scientific consensus is that GHGs are a big problem, and there is a large risk that they are a very big problem. That alone would push fossil fuels down below solar, wind and nuclear.

    Second, fossil fuels are not reliable. The US is still fighting a $2 trillion war to make access to oil slightly more reliable. An oil shock was a significant contributor to the 2008 recession, and has contributed to many recessions before that.

    Third, the problem of renewable intermittency is not so important. In the medium term Demand Side Management and fossil fuel backup will work just fine. In the long term , overbuilding, and geographic diversity will provide most of what’s needed, and synthetic fuels are perfectly viable for the small remaining percentage (they can be produced with current tech, at a price premium).

    Fourth, oil isn’t hard to replace. Land travel is very straightforward: freight can go to rail and short-haul electric trucks; passenger travel can go to EREVs and/or rail with car-shared EVs.

    Water shipping and air travel is a small percentage of fuel consumption. They can be made much more efficient; wind and solar can provide a large percentage of water shipping energy; and synthetic fuels can provide the relatively small amount of fuel still needed.

    Fossil fuels/oil are definitely not superior to the alternatives.

    Finally, to suggest that techno-optimism is harmful is to miss the fact that legacy FF industries are using scare tactics to keep us addicted to FF. The truth is that wind, solar and nuclear can provide energy that is cleaner, more scalable, more affordable and at least as reliable.

    • Good points—especially about oil not being so reliable anymore, and about the true cost of fossil fuels being far greater than what we pay at the pump.

      The fossil fuel reliability assessment is in some sense for the “good old days” when the resources were cheap and abundant. We’re moving into a much tougher phase. Yes, wars have been fought in connection with oil supply, and new ones are likely on their way. It is exactly because fossil fuels are about to become several notches less reliable that I am worried about how we deal with the problem.

      I agree that solar, wind, nuclear, etc. technologies can help us crawl out of the trap, but only if we fret about the future and start bold action now. The techno-optimism I fear is the blithe dismissal that technology will save us from collapse/disaster. Maybe, but I’d rather place my bets on something we can control and get to work like there’s no tomorrow.

    • While I agree that it is possible to end our reliance on fossil fuels without misery, I just don’t see that happening in our (American) political culture. Try telling people people that they wil have to Board a train rather than driving, and they’ll think you’re going to ship them off to auschwitz! A lot of people would probably rather pay $50 a gallon for gasoline rather than vote for higher taxes to build a new train system.

      I guess I’m a techno-optimist but also a political cynic. Anything that requires broad political organization and long-term planning is probably impossible for us.

      • Well, you did pull off the California aqueduct and a lot of other rather heavy longterm projects, done at a scale and with political and economical organization seldom seen earlier in history. That said, /the Car/ seems to be an absurdely strong sticking point for many, lending it a vast array of symbolism a transportation device really dosn’t deserve. Some use a leather jacket as a symbol of their freedom.

  45. Wonderful and very interesting website, thank you.
    We have become reliant on a transportation system that makes no long term sense. I love the idea of electric cars but that concept does not scale well. Indeed, many of our solutions to the end of oil do not scale well.
    If we were to replace all US automobiles and light trucks with electric versions the demand for electricity would require an approximate doubling of the US electric power grid generating capacity. We are already having a hard time replacing our current electric power demand with green energy, asking that we double it at the same time is just not going to happen.
    Unfortunately, I think the only way we’ll pull this off is as a full on crisis. My inherent optimism wants me to think that “at least we’ll make it work when there are no other excuses left.”
    Back to the transportation point for one last note: Long distance car travel and long distance trucking of goods is insane from an energy point of view. The bright side of things is that fixing that particular screw up will be the easiest of our problems to solve.

    • John, the existing grid in most places could easily accomodate large numbers of electric cars; most grid systems have a large diurnal range of demand, the existing unused capacity in low demand periods is huge. Additionally, numerous sources are reporting that an increasing percentage of EV buyers are also investing in their own solar PV systems, offsetting much if not all of their cars consumption. (Yes, of course I appreciate that this will not be appropriate for everyone.) Your point on the apparent senselessness of moving so much stuff over long distances is well taken, but this is a financially driven process. As the cost of transportation goes up as many of us expect then the whole paradigm will change accordingly.

  46. The matrix is missing “sustainability”. If we had unlimited oil supply, our descendants might have a very limited future. The problem has ceased to be that we do not have enough fossil fuels, the problem is that we cannot even afford – even economically – to burn off the reserves we have.

    “The oil companies, private and state-owned, have current reserves on the books equivalent to 2,795 gigatons — five times more than we can ever safely burn. It has to stay in the ground. Put another way, in ecological terms it would be extremely prudent to write off $20 trillion worth of those reserves.”

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