Comment: Replacing fossil fuels used for transportation -- and this is primarily oil, of course -- with something less CO2 intensive and more sustainable is an increasingly compelling problem. Although the installed infrastructure based on liquid fuels will present considerable economic and technological inertia for some time to come, long-term alternatives are worth exploring as well. The analysis in this paper shows that when a full analysis is employed, using biomass for conversion to electricity (and, therefore, battery-powered transportation) rather than conversion to ethanol is more sustainable.
As one who appreciates high-performance automobiles, I'm not sure I like this result, but there it is. If the battery problem can be overcome, however, I'll gladly purchase something like the Tesla vehicles. Currently, though, the batteries are too much of a kludge for me. HPH
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Greater Transportation Energy and GHG Offsets from Bioelectricity Than Ethanol
J. E. Campbell, D. B. Lobell, C. B. Field
Abstract: The quantity of land available to grow biofuel crops without affecting food prices or greenhouse gas (GHG) emissions from land conversion is limited. Therefore, bioenergy should maximize land-use efficiency when addressing transportation and climate change goals. Biomass could power either internal combustion or electric vehicles, but the relative land-use efficiency of these two energy pathways is not well quantified. Here, we show that bioelectricity outperforms ethanol across a range of feedstocks, conversion technologies, and vehicle classes. Bioelectricity produces an average of 81% more transportation kilometers and 108% more emissions offsets per unit area of cropland than does cellulosic ethanol. These results suggest that alternative bioenergy pathways have large differences in how efficiently they use the available land to achieve transportation and climate goals.
Originally published in Science Express on 7 May 2009
Print version in Science 22 May 2009: Vol. 324. no. 5930, pp. 1055 - 1057 DOI: 10.1126/science.1168885
(Note that this full article requires a Science magazine subscription or qualifying library for access, and it's copyrighted by the AAAS.)