What do you get when you cross an astronomically-inclined physicist with concerns over energy efficiency in lighting? Spectra. Lots and lots of spectra. In this post, we’ll become familiar with spectral characterization of light, see example spectra of a number of household light sources, and I’ll even throw in some mind-blowing photos. In the process, we’ll evaluate just how efficient lighting could possibly be, along the way understanding something about the physiology of light perception and the definition of the increasingly ubiquitous lighting measure called the lumen. Buckle your physics seat-belt and prepare to think like a photon.
I have described in a series of posts the efforts my wife and I have made to reduce our energy footprint on a number of fronts. The motivation stems from our perception that the path we are on is not sustainable. Our response has been to pluck the low-hanging fruit, demonstrating to ourselves that we can live a “normal” life using far less energy than we once did. We are by no means gold medalists in this effort, but our savings have nonetheless been substantial. Now we shift the burden off of ourselves, and onto our neighbors. You don’t have to run faster than the bear—just faster than the other guy. In this post, I summarize our savings relative to the national average, add a few more tidbits not previously covered, put the savings in context, and muse about ways to extend the reach of such efforts.
The Do the Math blog series has built the case that physical growth cannot continue indefinitely; that fossil fuel availability will commence a decline this century—starting with petroleum; that alternative energy schemes constitute imperfect substitutes for fossil fuels; and has concluded that a very smart strategy for us to adopt is to slow down while we sort out the biggest transition humans have ever faced. The idea is to relieve pressure on the system, avoid the Energy Trap, and give ourselves the best possible chance for a successful transformation to a stable future. Since building this case, I have described substantial adaptations in our home energy use, but have not yet addressed the one that bears most directly on the immediate problem: transportation and liquid fuels. Let’s take a look at what can be done here.
If you’re interested, oilprice.com posted an interview polling my take on energy alternatives and related issues. Regular Do the Math readers have likely heard much of it before, but perhaps will enjoy a different packaging…
A solar panel reaps only a small portion of its potential due to night, weather, and seasons, simultaneously introducing intermittency so that massive storage is required to make solar power work at a large scale. A perennial proposition for surmounting these impediments is that we launch solar collectors into space—where the sun always shines, clouds are impossible, and the tilt of the Earth’s axis is irrelevant. On Earth, a flat panel inclined toward the south averages about 5 full-sun-equivalent hours per day for typical locations, which is about a factor of five worse than what could be expected in space. More importantly, the constancy of solar flux in space reduces the need for storage—especially over seasonal timescales. I love solar power. And I am connected to the space enterprise. Surely putting the two together really floats my boat, no? No.
I’ll take a break from writing about behavioral adaptations and get back to Do the Math roots with an evaluation of solar power from space and the giant hurdles such a scheme would face. On balance, I don’t expect to see this technology escape the realm of fantasy and find a place in our world. The expense and difficulty are incommensurate with the gains.
When I first approached the topic of societal energy in 2004, I became aware for the first time that our energy future was not in the bag, and proceeded to explore alternative after alternative to judge the viability and potential pitfalls of various options. I have retraced my steps in Do the Math posts, exposing the scales at which different energy sources might contribute, and the practical complexities involved. My spooky campfire version of the story, a la Tolkien: The Way is Shut.
Alright, I’m overstating things a bit. The good news is that there do exist energy flows and sources that qualify as abundant or at least potent. However, many of the alternatives represent ways to produce electricity, which applies only to about one-third of our current energy demand. The immediate threat is therefore the short term liquid fuels crunch we will see when the global petroleum decline commences within the decade.
In this post, I will reflect on the lessons we learn after having characterized the various alternatives to fossil fuels. There will still be some tidying-up to do on energy alternatives not treated thus far, but by and large the nature of content on Do the Math is about to pivot toward addressing the question “What can we do now?” In some sense, a common thread so far has been: “easier said than done,” or “don’t count on that technology saving our bacon.” I’ve closed all the exits to get your attention. We’re boxed in. Okay, the exits aren’t really closed: they’re just not as wide open as they would need to be for me to be complacent. So now we’ll start looking at ways to nose out of our box in a safe and satisfying way.
Having looked at the major alternatives to fossil fuel energy production (summarized here), we come away with the general sentiment that the easy days of cheap energy are not evidently carried forward into a future without fossil fuels. That’s right, fossil fuels will be dead and gone. Is it time to pile them on the cart to be hauled away?
In the slapdash scoring scheme I employed in the alternative energy matrix, the best performers racked up 5 points, whereas by the same criteria, our traditional fossil fuels typically achieved the near-perfect score of 8/10. The only consistent failing is in the abundance measure, which is ultimately what brings us all together here at Do the Math. Fossil fuels are presently used in abundance—85% of current energy use—but this is a short-term prospect, ending within the century. The first effects of decline may be close at hand. Do I hear talk of nursing homes?
The gulf between fossil fuels and their alternatives tends to be rather large in terms of utility, energy density, practicality, ease of use, versatility, energy return on energy invested, etc. In other words, we do not merrily step off the fossil fuel ride onto the next one by “just” allowing the transition to happen. The alternatives come at a cost, and we will miss the golden days of fossil fuels. But wait…what’s that murmur? Not dead yet?
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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.
Ah, fusion. Long promised, both on Do the Math and in real life, fusion is regarded as the ultimate power source—the holy grail—the “arrival” of the human species. Talk of fusion conjures visions of green fields and rainbows and bunny rabbits…and a unicorn too, I hear. But I strike too harsh a tone in my jest. Fusion is indeed a stunningly potent source of energy that falls firmly on the reality side of the science fiction divide—unlike unicorns. Indeed, fusion has been achieved (sub break-even) in the lab, and in the deadliest of bombs. On the flip side, fusion has been actively pursued as the heir-apparent of nuclear fission for over 60 years. We are still decades away from realizing the dream, causing many to wonder exactly what kind of “dream” this is.
Our so-far dashed expectations seem incompatible with our sense of progress. Someone born in 1890 would have seen horses give way to cars, airplanes take to the skies, the invention of radio, television, and computers, development of nuclear fission, and even humans walking on the Moon by the age of 79. Anyone can extrapolate a trajectory, and this trajectory intoned that fusion would arrive any day—along with colonies on Mars. Yet we can no longer buy a ticket to cross the Atlantic at supersonic speeds, and the U.S. does not have a human space launch capability any more. Even so, fusion remains “just around the corner” in many minds.
With the exception of tidal energy, our focus thus far has been on land-based energy sources. Meanwhile, the ocean absorbs a prodigious fraction of the Sun’s incident energy, creating thermal gradients, currents, and waves whipped up by winds. Let’s put some scales on the energetics of these sources and see if we may turn to them for help. We’ve got our three boxes ready: abundant, potent, and niche (puny). Time to do some sorting!