Plants use photosynthesis, deriving the energy from the sun.
About a century ago, firewood was the most common form of fuel. The cheapest source of solar electricity is the wind power. Variation of pressure between areas caused by solar energy, causes wind effects. This form of energy is used to run turbines that in turn generate electricity. In the Rocky Mountains in Southern Wyoming, the average annual wind speed is 21 miles per hour, making it ideal for electricity generation.