Call it the nuclear power industry’s thirst trap.
The United States’ aging fleet of nuclear reactors ― responsible for one-fifth of the country’s electricity and most of its low-carbon power ― has never been more necessary as policymakers scramble to shrink planet-warming emissions. Yet the plants are struggling to stay afloat, with six stations shut down in the last five years and an additional 16 reactors scheduled to close over the next decade. So far, new coal- and gas-burning facilities are replacing them.
The nuclear industry blames high maintenance costs, competition from cheaper alternatives and hostile regulators concerned about radiation disasters like the 2012 Fukushima meltdown in Japan. But the country’s most water-intensive source of electricity faces what could be an even bigger problem as climate change increases the risk of drought and taxes already crumbling water infrastructure.
That finding, highlighted in the landmark climate change report that the Trump administration released with apparent reluctance last Friday, illustrates the complex and at times paradoxical realities of anthropogenic, or human-caused, warming. It also stokes an already hot debate over the role nuclear energy should play in fighting global warming, a month after United Nations scientists warned that carbon dioxide emissions must be halved in the next 12 years to avoid cataclysmic climate change leading to at least $54 trillion in damage.
The report ― the second installment of the Fourth National Climate Assessment, a congressionally mandated update on the causes and effects of anthropogenic warming from 13 federal agencies ― devoted its entire third chapter to water contamination and depletion. Aging, deteriorating infrastructure means “water systems face considerable risk even without anticipated future climate changes,” the report states. But warming-linked droughts and drastic changes in seasonal precipitation “will add to the stress on water supplies and adversely impact water supply.”
Nearly every sector of the economy is susceptible to water system changes. And utilities are particularly at risk. In the fourth chapter, the report’s roughly 300 authors conclude, “Most U.S. power plants … rely on a steady supply of water for cooling, and operations are expected to be affected by changes in water availability and temperature increases.”
For nuclear plants, that warning is particularly grave. Reactors require 720 gallons of water per megawatt-hour of electricity they produce, according to data from the National Energy Technology Laboratory in West Virginia cited in 2012 by the magazine New Scientist. That compares with the roughly 500 gallons coal requires and 190 gallons natural gas needs to produce the same amount of electricity. Solar plants, by contrast, use approximately 20 gallons per megawatt-hour, mostly for cleaning equipment, according to the Solar Energy Industries Association, a trade group.
Nuclear plants are already vulnerable to drought. Federal regulations require plants to shut down if water in the river or lake that feeds its cooling drops below a certain level. By the end of the 2012 North American heat wave, nuclear generation fell to its lowest point in a decade, with plants operating at only 93 percent of capacity.
The availability of water is one problem, particularly for the majority of U.S. nuclear plants located far from the coasts and dependent on freshwater. Another is the temperature of the water that’s available.
Nearly half the nuclear plants in the U.S. use once-through cooling systems, meaning they draw water from a local source, cool their reactors, then discharge the warmed water into another part of the river, lake, aquifer, or ocean. Environmental regulations bar plants from releasing used water back into nature above certain temperatures. In recent years, regulators in states like New York and California rejected plant operators’ requests to pull more water from local rivers, essentially mandating the installation of costly closed-loop systems that cool and reuse cooling water.
In 2012, Connecticut’s lone nuclear power plant shut down one of its two units because the seawater used to cool the plant was too warm. The heat wave that struck Europe this summer forced utilities to scale back electricity production at nuclear plants in Finland, Germany, Sweden, and Switzerland. In France, the utility EDF shut down four reactors in one day.
“Already they’re having trouble competing against natural gas and renewable energy,” said John Rogers, a senior energy analyst at the Union of Concerned Scientists. “Add onto that high water temperatures, high air temperatures and drought. It’s just another challenge.”
But water has yet to pose an existential crisis. The U.S. Nuclear Regulatory Commission said that it considers climate change when reviewing applications for nuclear plants’ construction or operation permits and that it has never rejected one over concerns about dwindling cooling water resources.
“For plants on lakes and rivers, the basic consideration will continue to be whether or not the water level in that body is high enough to meet the conditions of the license,” said Scott Burnell, a spokesman for the Nuclear Regulatory Commission. “To this point, there have been no indications in the NRC’s analyses to suggest that plants would have to deal with the potential for the water bodies to no longer be able to fulfill their function.”
If or when that situation arises, a plant would have to propose a plan to maintain the requirements of the license, likely by reducing water intake and cutting electricity production, he said.