All Biofuels Aren't Created EqualBiofuels can be made from nearly any organic material, but corn, which is the source of 95 percent of U.S. ethanol, would reduce global warming emissions only about 15 percent on average compared to gasoline. Cellulosic ethanol, made from switchgrass, slash, and agricultural byproducts, could cut emissions by more than 90 percent. But it's not commercially available. And then there's sugarcane ethanol, which is booming in Brazil, soybean biodiesel, and cooking grease biodiesel, even biodiesel made from algae -- all with their various pros and cons.
Want help separating the wheat from the chaff? Check out "Bio-hope, Bio-hype" in the most recent issue of Sierra, complete with a useful chart comparing six different biofuels.