Category Archives: Bio Energy

Energy derived from biological sources

Inexhaustible Flows?

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Photo from Monash Universiry

I recently came across a statement to the effect that once we transition away from fossil fuels to renewable energy like solar, wind, and hydro, we would essentially be home free for the long run—tapping into inexhaustible flows. It is a very pleasant notion, to be sure, and one that I believe is relatively common among enthusiasts for renewable energy.

Naturally, I am concerned by the question of: what magnificent things would we do with everlasting copious energy? As an excellent guide, we can ask what amazing things have we done with the recent bolus of energy from fossil fuels? Well, in the course of pursuing material affluence, we have eliminated 85% of primeval forest, made new deserts, created numerous oceanic dead zones, drained swamps, lost whole ecosystems, almost squashed the remaining wild land mammals, and initiated a sixth mass extinction with extinction rates perhaps thousands of times higher than their background levels—all without the help of CO2 and climate change (which indeed adds to the list of ills). These trends are still accelerating. Yay for humans, who can now (temporarily) live in greater comfort and numbers than at any time in history!

But the direction I want to take in this post is on the narrower (and ultimately less important) technical side. All the renewable energy technologies rely on non-renewable materials. Therefore, inexhaustible flows are beside the point. It’s like saying that fossil fuel energy is not practically limited by available oxygen for combustion, so we can enjoy fossil fuels indefinitely. Or that D–T fusion has billions of years of deuterium available, when there’s no naturally-occurring tritium (thus reliant on limited lithium supply). In a multi-part system, the limiting factor is, well, the limiting factor. Sure, into the far future the sun will shine, the wind will blow, and rain will fall. But capturing those flows to make electricity will require physical stuff: all the more material for such diffuse flows. If that stuff is not itself of renewable origin, then oops. The best guarantee of renewability is being part of natural regeneration (i.e., of biological origin). If solar panels, wires, inverters, and batteries were made of wood and the like: alright, then.

Recognizing that biological organisms—plants and the animals that directly or indirectly draw energy from them—have already figured out how to tap into (essentially) inexhaustible flows—solar, primarily—I became interested in comparing the performance of the human animal to that of a solar panel or wind turbine, in terms of mineral requirements. After all, the biosphere gets by without mining the depths. So let’s dig into the material requirements of life.

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The Alternative Energy Matrix

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[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.

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MPG of a Human

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On Do the Math, three previous posts have focused on transportation efficiency of gasoline cars, electric cars, and on the practicalities of solar-powered cars. What about personal-powered transport—namely, walking and biking? After stuffing myself over Thanksgiving, I am curious to know how potent human fuel can be. How many miles per gallon do we get as our own engines of transportation?

Okay, the “miles” part is straightforward. And we can handle the “per.” But what’s up with the gallon? A gallon of what? Here we have all kinds of options, as humans are flex-fuel machines. But food energy is not much different from fossil fuel energy in terms of energy density.

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The Biofuel Grind

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[An updated treatment of some of this material appears in Chapter 14 of the Energy and Human Ambitions on a Finite Planet (free) textbook.]

When we enter the decline phase of conventional oil—likely before 2020—we will scramble to fill the gap with alternative liquid fuels. The Hirsch Report of 2005, commissioned by the U.S. Department of Energy, took a hard look at alternatives that could respond to the scale of the problem in time to have an impact. Not one of the approaches deemed to be currently viable in the report departs from fossil fuels. But what about biofuels? To what extent can they solve our problem? We’ll dip our toes into the math and see where a first-cut analysis leaves us.

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Garbage In, Garbage Out

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How many times have you heard it: if we could tap into the energy embedded in our copious waste streams, we could usher in a new era of energy independence—freeing ourselves of the need to support oppressive regimes who happen to sit atop the bulk of the oil reserves in the world. In fact, these sorts of claims are abundant enough to give the impression that we have a cornucopia of fresh (and sometimes not so fresh) energy solutions to pursue if we got really serious. This is a hasty and dangerous conclusion, so in this case, waste makes haste.

I consider this perceived abundance of technological solutions to be one of our worst enemies in developing sensible solutions to the coming fossil fuel energy crunch. If ideas abound, each claiming some ability to free us of foreign oil, then surely we’ve got the situation under control and don’t need to invest substantial time and energy today to solve what looks like a non-problem of tomorrow. But what if the claims are overblown, hyped, or just plain wrong? At best, this is irresponsible behavior. At worst, the resulting sense of complacency could delay substantive action to our ruin. Continue reading →

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