There’s some more good news about cellulosic ethanol, a fuel derived from grasses and other nonfood sources. It’s long been estimated that the amount of energy in such fuels will be much more than the energy required to make them–which is not the case with corn-grain-based ethanol. Now experimental results are in, and the ratio of energy produced to energy used is even better than expected. The renewable energy produced was 540 percent more than the nonrenewable energy used to make it. Previous studies estimated that the number would be more like 340 percent. The improvement comes, basically, from farmers using less energy than researchers thought they would to grow switchgrass, one of the proposed cellulosic sources.

The better ratio means that cellulosic ethanol could do more to reduce greenhouse-gas emissions than previously thought. That’s particularly good news, since new legislation will require that some 21 billion gallons of fuel be made from such non-corn-grain sources. The trick now is to improve methods for converting switchgrass into ethanol–making the processes cheaper–and to get farmers to start growing switchgrass in large amounts.