Westar Energy is an investor owned electric utility headquartered in Topeka, Kansas. Westar is the largest electric company in Kansas, serving 690,000 residential, commercial and industrial customers in the eastern third of the state. Westar Energy generates more than 27,000,000 megawatt-hours of electricity per year at its 12 power plants. Westar Energy service territory covers 10,130 square miles (26,200 km2) in east and east-central Kansas.