To reduce greenhouse gas emissions from making ethanol, researchers figured out the best ways to grow crops and make the fuel. They chose mostly switchgrass and a bit of corn as the main materials. The U.S. mainly creates ethanol from switchgrass grown on less useful land in the central and western parts of the country. Other countries like China, Brazil, the EU, and others also produce ethanol and send it to the U.S. The total emissions from making and using this ethanol are 43.2 grams of CO2 per megajoule. Nearly all of these emissions come from directly making the fuel, not from changing how land is used.