RWE AG, until 1990: Rheinisch-Westfälisches Elektrizitätswerk AG (Rhenish-Westphalian Power Plant), is a German electric utilities company based in Essen, North Rhine-Westphalia. Through its various subsidiaries, the energy company supplies electricity and gas to more than 20 million electricity customers and 10 million gas customers, principally in Europe. RWE is the second largest electricity producer in Germany, and has increased renewable energy production in recent years. RWE previously owned American Water, the United States' largest investor-owned water utility, but this was divested in 2008. It also owned RWE Dea (now DEA AG), which produced some of the oil and gas RWE sold (annual production is around 2 million m3 of crude oil (about 365,000 BOE) and 3 billion m3 of natural gas (about 18 million BOE, 49,300 BOE) a day. RWE confirmed in December 2015 that it would separate its renewable energy generation, power grid and retail operations into a separate company during 2016, and sell a 10% holding in the business through an initial public offering. The restructuring was caused by an effort to reduce the group's exposure to nuclear decommissioning costs, required due to a German government policy of closing all nuclear power stations by 2022.