I know that solar energy can be used to make electricity and to heat water and air. But can solar power also be used to make liquid fuels? Until recently, the practical answer was "no." Photovoltaic panels absorb sunlight and use it to create an electric current, while thermal solar devices use sunlight to heat water and buildings. Liquid fuels such as gasoline, diesel, and ethanol are made mostly by refining fossil fuels such as oil or renewable fuels such as corn and carbohydrate rich plants. But because making fuels involves chemical reactions at high temperatures, researchers are now experimenting with ways to bring solar energy into the mix.