In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
Q: What are backup stations using?, Context: Electricity in the Richmond Metro area is provided by Dominion Virginia Power. The company, based in Richmond, is one of the nation's largest producers of energy, serving retail energy customers in nine states. Electricity is provided in the Richmond area primarily by the North Anna Nuclear Generating Station and Surry Nuclear Generating Station, as well as a coal-fired station in Chester, Virginia. These three plants provide a total of 4,453 megawatts of power. Several other natural gas plants provide extra power during times of peak demand. These include facilities in Chester, and Surry, and two plants in Richmond (Gravel Neck and Darbytown).
A:
natural gas