an uprate or derate.

The June 16 edition of Today in Energy examined the wide age range of all electric power generators for all fuels; today's article looks specifically at natural gas-fired generators. At the end of 2010, natural gas-fired generators constituted 39% of the Nation's total electric generation capacity of 1,042 gigawatts (GW). Nearly 237 GW of natural gas-fired generation capacity was added between 2000 and 2010, representing 81% of total generation capacity additions over that period.

Capacity additions for most fuels decreased during the 1980s, compared to the 1970s. This reflected several factors, including a lower growth rate for electric power demand in the 1980s 1 and capacity overbuilding during the 1970s. In the case of natural gas, other factors were supply shortages and price increases in the1970s and early 1980s. In addition, the Federal Powerplant and Industrial Fuel Use Act of 1978 discouraged the use of natural gas and petroleum for power generation.

By the late 1980s and early 1990s, an improved price and supply outlook for natural gas, and more efficient combined-cycle technology, encouraged greater use of natural gas for power generation (the restrictive provisions of the Fuel Use Act were repealed in 1987). With power industry restructuring in the 1990s, the construction of new power plants was dominated by independent power producers who favored natural gas generation due to short construction times and low capital costs.

About 65% of the existing natural gas capacity added after 1980 is combined-cycle units. As a whole, average utilization of the Nation's fleet of natural gas combined-cycle gas