Wind energy releases no pollution into the air or water, and does not contribute to global warming. According to the American Wind Energy Association, "on average, each MWh of electricity generated in the U.S. results in the emission of 1,341 pounds of carbon dioxide (CO2), 7.5 pounds of sulfur dioxide (SO2) and 3.55 pounds of nitrogen oxides (NOx). Thus the 10 million MWh of electricity generated annually by U.S. wind farms represents about 6.7 million tons in avoided CO2 emissions, 37,500 tons of SO2 and 17,750 tons of NOx. This avoided CO2 equals over 1.8 million tons of carbon, enough to fill 180 trains, each 100 cars long, with each car holding 100 tons of carbon every year." And unlike most other electricity sources, wind turbines do not consume water.