The United States is the world’s largest producer of nuclear power, but the country’s fleet of nearly 100 reactors is showing its age.
On Nov. 2, the owner of a nuclear power station in New York said it will shut the plant down, which follows announcements of plant closures in Massachusetts, California, Florida, and Wisconsin. This raises important questions for the U.S. energy sector. The retirements reflect a set of economic challenges for nuclear power plants across the United States and have important implications for climate change, energy costs, and the reliability of the power grid.
Nuclear provides nearly 20 percent of the electricity in the United States, but the average plant is about 34 years old, and prospects for the future of many of these plants are murky, at best. While five new reactors are currently under construction in the United States, the World Nuclear Association estimates that more than 10 older ones are currently at risk of closure.
The explanation for these retirements and the limited amount of new construction is simple: cost.
Abundant and cheap natural gas coupled with the rapid expansion of wind power has limited increases in electricity prices, making it harder for some nuclear operators to justify continued operations or make expensive repairs. By 2020, the U.S. Energy Information Administration estimates that the cost of bringing new nuclear online will be about 25 percent more expensive than natural gas or wind.
But nuclear power is by far the most important source of non-CO2-emitting electricity in the United States. And while renewables like wind and solar have grown rapidly, they respectively accounted for just 4 percent and 0.4 percent of U.S. electricity generation in 2014.
So as the existing nuclear fleet ages and eventually retires, what will happen to domestic CO2 emissions?
Regional Picture
If nuclear power were somehow replaced entirely by wind and solar, emissions would remain flat—a best-case scenario.
The U.S. electricity system produces about 500 tons of CO2 for every gigawatt-hour of power generated, and if all of today’s nuclear power were replaced by natural gas, total power sector CO2 emissions would grow by roughly 15 percent.
Take as an example Japan, which after the 2011 meltdown at Fukushima-Daiichi ordered all nuclear units closed. Nuclear power was replaced by coal, oil, and gas-fired generation (the country also adopted increased energy-conservation measures). Most reactors are still offline, and Japanese CO2 emissions in 2014 were roughly 20 percent higher than they were in 2010, the year before the earthquake.
