Wind energy is one of the fastest growing energy sources in the world. In the United States, the installed capacity of wind energy grew by an incredible 45% in 2007 and another 50% in 2008. The United States installed 8,358 MW of new wind energy in 2008. Wind energy is growing at this rate because the cost of electricity produced by wind energy is competitive with electricity produced by natural gas, oil, coal, or nuclear power. Also, wind energy is a clean, renewable technology that does not contribute to global warming. This makes it a healthier, more sustainable choice than other forms of electricity generation.