RWE RWE headquarters in Essen. RWE AG (until 1990: Rheinisch-Westf lisches Elektrizit tswerk AG) is a German energy company founded in 1898, based in Essen. Through its subsidiaries controls and distributes electric power and water and gas primarily in Europe and North America. The RWE is the second largest power producer in Germany after E.ON. Opera in America through the American Water Works subsidiaries and Calame (California American Water).