Last year California passed a much-heralded law requiring oil companies to cut the carbon intensity of their fuel 10 percent by 2020. The state is allowing ethanol to be used as one low-carbon substitute, and recently raised the cap on ethanol in gasoline from six to ten percent. You've probably read about the ways the ethanol craze contributes to higher food prices around the world, but what nobody has calculated, until now, is how this affects ethanol's true carbon footprint. In an analysis released January 17th, two UC Berkeley researchers found that ethanol actually produces more carbon emissions than gasoline. As a result, the carbon intensity of California fuel has ironically risen, between 3 and 33 percent.
The researchers, professors Michael O'Hare and and Alexander Farrell, take issue with the model state regulators used to calculate ethanol's carbon output, arguing that it did not factor in the indirect effects on the global food supply. Among other things, higher corn prices cause farmers half-way around the world to convert more forests into farmland, and those trees are then burned or decay, releasing more carbon into the atmosphere. The professors pointed this out in a letter sent earlier this month to the California Air Board, which is discussing changing its carbon model in light of the findings.