High Quality Content by WIKIPEDIA articles! Constellation Energy, headquartered in Baltimore, Maryland, is an energy producer, trader, and distributor. The company operates over 35 power plants in 11 states (mainly Maryland, Pennsylvania, New York, West Virginia, and California) under its operating company Constellation Commodities Group and/or Constellation Generation Group. Constellation Energy is a Fortune 500 company and is one of the top electricity producers in the United States.