Fuel cell fuel cells so efficiencies vary, but most are between 40% and 60% energy efficient. However, when the fuel cell's waste heat is used to heat a building in a cogeneration system this efficiency can increase to 85%. This is significantly more efficient than traditional coal power plants, which are only about one third energy efficient. Assuming production at scale, fuel cells could save 20–40% on energy costs when used in cogeneration systems. Fuel cells are also much cleaner than traditional power generation; a fuel cell power plant using natural gas as a hydrogen source would create less than one ounce
Ethanol fuel by country and Hawaii — require ethanol to be blended with gasoline motor fuel. Many cities also require ethanol blends due to non-attainment of federal air quality goals. Several motor vehicle manufacturers, including Ford, Chrysler, and GM, sell flexible-fuel vehicles that can use gasoline and ethanol blends ranging from pure gasoline all the way up to 85% ethanol (E85). As of early 2013, there were about 11 million E85-compatible vehicles on U.S. roads, though actual use of E85 fuel is limited, not only because the ethanol fueling infrastructures is limited, but also because many owners are not aware their vehicle is flex-fuel