MPG of a Human

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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A Solar-Powered Car?

If you like the sun, and you like cars, then I’m guessing you’d love to have a solar-powered car, right? This trick works well for chocolate and peanut butter, but not so well for garlic bread and strawberries. So how compatible are cars with solar energy? Do we relish the combination or spit it out? Let’s throw the two together, mix with math, and see what happens.

What Are Our Options?

Short of some solar-to-liquid-fuel breakthrough—which I dearly hope can be realized, and described near the end of a recent post—we’re talking electric cars here. This is great, since electric drive trains can be marvelously efficient (ballpark 85–90%), and immediately permit the clever scheme of regenerative braking.

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Pump Up the Storage

If we adopt solar and wind as major components of our energy infrastructure as we are weaned from fossil fuels, we have to solve the energy storage problem in a big way. An earlier post demonstrated that we do not likely possess enough materials in the world to simply build giant lead-acid (or nickel-based or lithium-based) batteries to do the job. Comments frequently pointed to pumped hydro storage as a far more sensible answer. Indeed, pumped storage is currently the dominant—and nearly only—grid-scale storage solution out there. Here, we will take a peek at pumped hydro and evaluate what it can do for us.

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The Biofuel Grind

[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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Growth Has an Expiration Date

Just a quickie.  A few weeks back, I tried to cram four Do the Math posts into a 20 minute talk, delivered at the Compass Summit.  For those of you who would rather watch 23 minutes of video than sit down to read four posts, here is a link to the video of the talk.  Perhaps you’ll see why I should stick to writing.

Growth Has an Expiration Date from Compass Summit on FORA.tv

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Peak Oil Perspective

It was by teaching a course on energy in 2004 that I first became aware of the enormous challenges facing our society this century. In preparing for the course, I was initially convinced that I would identify a sensible and obvious path forward involving energy from solar, wind, nuclear, geothermal, tides, waves, ocean currents, etc. Instead, I came out dismayed by the hardships or inadequacies on all fronts. The prospect of a global peak in oil production placed a timescale on the problem that was uncomfortably short. It took several exposures to peak oil for me to grasp the full potential of the phenomenon to transform our civilization, but eventually I was swayed by physical and quantitative arguments that I could not blithely wave off the problem—despite a somewhat unsettling fringe flavor to the story.

Aside from excursions here and there, Do the Math represents—in computer terms—a “core dump” of years of accumulated thoughts and analysis on energy, growth, and the largely unappreciated challenges we face on both short and long terms. During this queued process—with much more to come—I have made references to peak oil, but have refrained from a head-on treatment. As important as peak oil has been in motivating my quantitative exploration of life beyond fossil fuels, it seems overdue that I share my thoughts.
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