Sustainable Energy - without the hot air

Posted on September 17, 2009 by Steve

In his "straight-talking book about the numbers," David J.C. MacKay provides a clear, balanced look at the possibilities of a future without carbon-based energy. He does not argue for one alternative or another (though nuclear advocates will find much to like), and repeatedly claims that the only position he espouses is that "we should have a plan that adds up." To cut through the "flood of crazy innumerate codswallop" he uses a wonderfully simple device: a stacked bar chart of average energy consumption, in consistent units of kilowatt hours per day per person. He recognizes his necessary simplifications, even calling some of his models "cartoons," but the result is an unambiguous picture of roughly where our energy is spent and how much might be generated without fossil fuel.

Chapter by chapter, he attempts to balance typical consumption with a parallel chart of theoretical alternative energy production. From the start, it is an uphill climb. A typical car driver consumes about 40 kWh per day driving. Massive wind energy infrastructure covering 10% of Britain's land area could generate half of that, 20 kWh per day per person. As a dieter finds it all too easy to consume a few more calories and hard to work them off, the consumption chart climbs ever higher while the alternative production side struggles to keep up. If you take one intercontinental jet flight each year, you consume another 30 kWh (daily average) to power the flight. ("Planes are twice as fuel-efficient as a single-occupancy car," i.e. the same, per person per mile, as a car with a driver and a passenger and worse than a vehicle with many passengers.) Solar thermal panels on every south-facing roof could provide 13 kWh per day per person. Heating, cooling, and the making and transporting of manufactured goods are significant sources of additional energy demand. With back-of-the-envelope calculations, it becomes apparent that even using all of the green energy sources to their practical maximum extent, there will be a shortage. And this is based on physical limits alone, without considering financial costs, popular acceptance, and political will.

Do we need to bother making the switch? MacKay is carefully neutral, but offers three motivations for the conversation: the finite supply of fossil fuels, energy security, and climate change. On this last one, he is sensitive to "climate-change inactivists" and merely claims that "it’s very probable that using fossil fuels changes the climate." Regardless of necessity, the practicality of many proposed energy sources should inform the dialog. Setting aside costs, the weak concentration of green energy sources means that the amount of space they require is a significant factor. A chart of renewable energy sources measured in watts generated per square meter has the sobering conclusion that "facilities have to be country-sized."

Perhaps what's most surprising and enjoyable about the book is the tone. Excusing himself from advocating any particular solution, he focuses on facts and figures, so the text is friendly, informative and not confrontational. Extensive notes provide details, and an appendix of "technical chapters" introduce equations and diagrams to expand on the cartoon models and justify estimates. There is a definite focus on Great Britain, both in the examples cited and the language. An American might well misunderstand, as I did, this sentence: "A pumped-storage chamber one kilometre below London has been mooted." The meaning becomes more clear later on, with the sentence "A 1.2GW high-voltage DC interconnector to Norway was mooted in 2003, but not built." MacKay mocks the British saying "every little helps" when used to justify pointless exercises like unplugging cell phone chargers. "A more realistic mantra is: if everyone does a little, we’ll achieve only a little."

The graphics are also almost all excellent. The repeated stacked bar chart of energy sources is brilliantly simple, and becomes so familiar that it makes a diagram of the theoretical windfall from fusion jaw-dropping. I've seen comparisons made to Tufte, but there's an ugly chart here and there that make this an exaggeration. I did like the graphic on bird kills, though.

Best of all is the clear thinking. Again and again he exposes ridiculous claims and energy foibles:
Glendoe [hydroelectric project] has been billed as “big enough to power Glasgow.” But if we share its 180GWh per year across the population of Glasgow (616 000 people), we get only 0.8 kWh/d per person. That is just 5% of the average electricity consumption of 17 kWh/d per person. The 20-fold exaggeration is achieved by focusing on Glendoe’s peak output rather than its average, which is 5 times smaller; and by discussing “homes” rather than the total electrical power of Glasgow.
Fuelling the Hydrogen 7, the hydrogen-powered car made by BMW, requires 254 kWh per 100 km – 220% more energy than an average European car.... I know of no form of land transport whose energy consumption is worse than this hydrogen car. (The only transport methods I know that are worse are jet-skis – using about 500 kWh per 100 km – and the Earthrace biodiesel-powered speed-boat, absurdly called an eco-boat, which uses 800 kWh per 100 p-km.)

The price is right too. The complete PDF is available on the site as well as a ten-page synopsis.
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Posted by Jonathan Misirian | September 23, 2009 | 15:53:22

I read recently James Lovelock's, The Vanishing Face of Gaia, and loved it immeasurably so. Lovelock, the father the Gaia movement, which purports that the earth is a living organism in its totality, writes with a contrarian world view. You would love the book, I’m sure of it… but he also makes the case for nuclear energy, long the red-headed step-child of the environmental movement. He writes like Michael Pollan, free of commercial interests or governmental subsidies or even of any intellectual movements. Lovelock’s writing crosses the conservative-liberal divide and makes some similar intellectual points as does your article… Thanks Steve…

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