NRG Energy, Inc.?is a large American energy company, dual-headquartered in Princeton, New Jersey?and?Houston,?Texas.?It was formerly the wholesale arm of?Northern States Power Company?(NSP), which became?Xcel Energy, but became independent in 2000. NRG Energy is involved in energy generation and retail electricity.Their portfolio includes nuclear generation, coal generation, wind generation, utility scale generation, distributed solar generation, and oil generation.NRG serves 2.9 million retail customers in Texas, Connecticut, Delaware, Illinois, Maryland, Massachusetts, New Jersey, New York, Pennsylvania, Ohio, and the District of Columbia.