Output of electricity reached 7,100 million kWh in 2000, of which 69.6% was from hydroelectric sources and 30.4% was from fossil fuels; at the beginning of 2001, total installed capacity was 1,200 MW. The greatest single source of power is the Volta River Project, begun in 1962 and based on a hydroelectric installation at Akosombo, about 100 km (60 mi) northeast of Accra. Work on the Akosombo (or Volta River) Dam was finished in 1965. The first stage of the electrification project was completed in mid-1967 and had a capacity of 512,000 kW; by 1990, the plant's capacity had been expanded to 912 MW. Ghana's other major hydroelectric plant is at Kpong (160 MW). The Volta River Authority supplies 99% of the total national electricity consumption, 50–60% of which is absorbed by aluminum refining. Excess electricity is sold to Togo, Benin, and Côte d'Ivoire. A $150 million project to extend the main grid to northern Ghana was completed in 1991.
Beginning in the 1970s, oil exploration was conducted offshore and in the Volta River Basin. In 1979, an offshore field developed by Agri-Petco, a US company, began operations; it was later taken over by Primary Fuel, also a US company, but production ceased in 1986. The Ghana National Petroleum Corporation, which was established in 1984, reported production of oil at the rate of 6,000 barrels per day at the South Tano Basin in 1991. By 1994, total Ghanaian crude oil production totaled only 1,400 barrels per day, but it rose to 7,000 by 2000, compared with consumption totaling 31,000 barrels per day in the same year. Nigerian oil accounts for the bulk of petroleum imports. Recoverable oil reserves were estimated at 16.5 million barrels in 2000. Natural gas reserves, located primarily in the Tano fields, were estimated at 23.8 billion cu m (840 billion cu ft) in the same year.