Fossil fuels like oil, coal and natural gas are non-renewable and contribute greatly to pollution, leading to a search for alternative fuels. Ethanol from corn and biodiesel from soybeans are two biofuel options examined. Ethanol production relies heavily on corn, which depletes soils and drives up food prices as more land is used for crops. Biodiesel generates over 90% more energy than is required to produce it and emits less greenhouse gases than ethanol. Alternative fuels are needed to replace fossil fuels and reduce environmental impacts.