Fat can power cars, too. Biodiesel is a nontoxic and biodegradable fuel made from things like animal fat, vegetable oil and restaurant grease. Some species of algae can even excrete tiny drops of usable oil. In the United States, production of biodiesel currently stands at about 75 million gallons annually.
Although you can use vegetable oils directly — though not for legal resale — mixing oil with alcohol and a catalyst creates a higher-quality fuel. Typically, vehicles that use petroleum diesel can also use biodiesel without many alterations. Biodiesel also yields 90 percent more energy than corn ethanol, and it gives off almost 70 percent less GHG.