Age of electric power generators varies widely

The current fleet of electric power generators has a wide range of ages. The oldest power plants tend to be hydropower generators. Most coal-fired plants were built before 1980. There was a wave of nuclear plant construction from the late 1960s to about 1990. The most recent waves of generating capacity additions include natural gas-fired units in the 2000s and renewable units, primarily wind, coming online in the late 2000s.

An upcoming series of Today in Energy articles will examine trends in generating capacity additions by fuel type, for coal, hydro, nuclear, natural gas, petroleum, and wind. The 'other' category includes solar, biomass, and geothermal generators, as well as landfill gas, municipal solid waste, and a variety of small-magnitude fuels such as byproducts from industrial processes (e.g., black liquor, blast furnace gas).

About 530 GW, or 51% of all generating capacity, were at least 30 years old at the end of 2010 (see chart below). Most gas-fired capacity is less than 10 years old, while 73% of all coal-fired capacity was 30 years or older at the end of 2010.