This document discusses different sources that produce electricity in the United States. It states that coal plants produce 44% of US electricity and burn over 1 million tons of coal per year. Hydroelectric power accounts for 16% of global electricity and is expected to increase 3.1% annually. Wind turbines convert kinetic energy from wind into electricity and are used in large wind farms. Solar power directly converts sunlight to electricity using photovoltaics or concentrates solar energy using mirrors to power generators. Electricity is transmitted through power lines to distribution centers and then to homes and businesses.