Biofuels are fuels made from new biological (living, carbon based) resources. The two most common forms of biofuels are Bioethanol and Biodiesel. Bioethanol is an alcohol made by fermentation, mostly from carbohydrates produced in sugar or starch crops such as corn or sugarcane. Biodiesel is similar in composition to the fossil fuel diesel and is a liquid that can be made from animal fats, vegetable oils, and many types of seed oil such as soy, canola, flax, palm and hemp. Critics have voiced concerns that an increase in the U.S. production of biofuels, and, in particular the current push for corn and soy based ethanol (i.e. calls for the production of 36 billion US gallons of renewable fuels by 2022, including 15 billion US gallons of corn-based ethanol) will increase soil degradation, erosion, and water pollution. Corn and soy based ethanol have also been criticized as being inefficient, of using more fuel to produce, than the end product.