pg&e corporation, through its subsidiary, pacific gas and electric company, engages in the sale and delivery of electricity and natural gas to customers in northern and central california, the united states. it generates electricity using nuclear, hydroelectric, fossil fuel-fired, fuel cell, and photovoltaic sources. as of december 31, 2019, the company owns and operates approximately 18,000 circuit miles of interconnected transmission lines, 33 electric transmission substations, approximately 107,000 circuit miles of distribution lines, 68 transmission switching substations, and 760 distribution substations; and natural gas transmission, storage, and distribution system consisting of approximately 43,300 miles of distribution pipelines, approximately 6,300 miles of backbone and local transmission pipelines, and various storage facilities. it serves residential, commercial, industrial, and agricultural customers, as well as natural gas-fired electric generation facilities. the company