industrial--manufacturing

Almost a third of the fats produced in the U.S. come from animals rather than vegetables. Vegetable oils are more popular and widely used, but animal fat products are actually cheaper to produce. But because of the way they are processed, most animal fats aren't considered to be food-grade, and therefore are not consumable by humans. The good news is that, through a process of using screener separators and other methods to reduce impurities, animal fats can be purified enough for use as a biodiesel fuel.