CPS Energy of San Antonio, Texas (formerly "City Public Service"), has combined natural gas and electric service. Fourteen percent of all utility revenues are returned to the City of San Antonio, and those revenues make up more than 20 percent of the City of San Antonio's annual operating budget. Acquired by the City in 1942, CPS Energy serves over 741,000 electricity customers and more than 331,000 natural gas customers in its 1,566-square-mile (4,060 km2) service area, which includes Bexar County and portions of its 7 surrounding counties. CPS Energy's diverse fuel generation mix includes nuclear power (35%), coal (34%), natural gas (15%) and renewable energy (16 percent).