Our non-renewable energy sources such as coal, oil, and natural gas will (1) __________ out in the future. That's the (2) __________ why we are looking for alternative sources of (3) __________ which are cheap, clean and effective. These (4) __________ of energy will not cause (5) __________ or waste natural resources. (6) __________ power is one of them. It's currently the cheapest source of large-scale renewable energy. Most wind energy is produced from turbines that have three 60-meter-long blades. The wind spins the blades, which turn a shaft connected to a generator that produces (7) __________. Now, mass production and technology advances are (8) __________ turbines cheaper. In 2000, cumulative wind capacity (9) __________the world was 17,000 megawatts. Fifteen years later, this number increased sharply to 430,000 megawatts. It is predicted that with this pace of growth, (10) in 2050 one third of the world's electricity needs will be fulfilled by wind power.