Human World

Crops for electricity yields more miles than ethanol

A new study shows that burning crops for electricity, such as corn and switchgrass, to create electricity to power electric vehicles would actually yield more transportation miles than turning those crops into ethanol.

The method would also reduce greenhouse gas emissions more than turning the crops into ethanol and using that ethanol in vehicles with internal combustion engines. The findings hold true for both corn and switchgrass as feedstocks — switchgrass being a source of cellulosic ethanol, where most of the plant is used.

The researchers found that using biomass to produce electricity for electric vehicles would produce 81 percent more transportation miles than using the same amount of crops to produce ethanol. In one example using switchgrass and a small SUV, the researchers calculated that the SUV would go 8,000 miles per acre on ethanol, but a comparable electric SUV would go 15,000 miles per acre on electricity generated by that acre of switchgrass. (View the scientists’ Ethanol vs. Electricity graphic.)

Published in the online version of Science by scientists at the University of California-Merced, Stanford University and the Carnegie Institution, the study — “Greater Transportation Energy and GHG Offsets from Bioelectricity Than Ethanol” — recommends that the crops be grown on marginal agricultural land or abandoned agricultural lands, to prevent cutting into food crops for people. Elliott Campbell of the University of California-Merced was the lead author.

Using plants to create electricity to power electric vehicles wins out because electric engines are much more efficient than internal combustion engines.

Listen to a podcast interview with Campbell here.

May 8, 2009
Human World

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