Thermal power plants will face growing constraints as a result of climate change, with temperature-related curtailments potentially causing billions of dollars in lost revenue and requiring a significant buildout of global capacity, according to climate researchers.
A new study estimates that each degree C of global warming will increase global curtailment of thermal power plants by 0.8 to 1.2 percentage points during times of peak electricity demand. The resulting power loss could create the need for an additional 18 GW to 27 GW of new capacity to offset the losses, according to an article presenting the study's findings published Dec. 17 in the Environmental Research Letters journal.
The analysis quantifies the potential future risk from heatwaves and droughts that have already hit power plants in the U.S. and Europe with increasing frequency over recent years. A 2018 heatwave that swept across Europe caused widespread shutdowns at nuclear plants, from France to Finland, and utilities have also been forced to throttle their plants over the past two years.
In the U.S., an analysis by S&P Global Market Intelligence found that more than half of the fossil-fueled and nuclear plants in the Lower 48 are located in areas forecast to face climate-related water stress by the end of this decade under a business-as-usual scenario.
Water and air cooling systems used at thermal plants become less efficient at higher temperatures and operators also have to curtail or shut down their plants because of local regulations that limit water withdrawal during drought or periods of high temperatures.
"Recent heat waves have reduced power generation capacity in Europe, and a hotter and drier future may make such curtailment events more common, creating an imperative to compensate for the resulting reduced electricity generation," the researchers wrote in their article.
The study, titled "Thermal power generation is disadvantaged in a warming world," was produced by Ethan Coffel, an assistant professor in the Department of Geography and the Environment at Syracuse University, and Justin Mankin, an assistant professor in the Department of Geography at Dartmouth College.
For their analysis, the researchers combined temperature and water runoff data with power plant outage records for nuclear plants in the U.S., as well as coal, gas and oil-fired plants in the EU, in order to estimate future curtailments.
They applied the results to the global fleet of power plants and found that climate change has already increased average curtailments at thermal plants by 0.75 to 1 percentage points to date.
"Relative to policy scenarios with global transitions to renewable portfolios or that allow aging plants to retire, thermal power generation is a systemically disadvantaged means of electricity production in a warming world," they wrote.
Largely due to higher air conditioning use, peak electricity demand in the U.S. is already expected to increase by 10 to 20 percentage points under 2 degrees C of warming, and by 30 to 50 percentage points under 4 degrees C, according to the researchers.
But potential curtailments and their likely impact also rely to a large degree on the trajectory of power systems. Applied at a global scale, the researchers' model suggests that aggregated curtailment could translate into lost revenue of up to $47 billion per year by the end of the century under the International Energy Agency's Stated Policies scenario, which assumes thermal plant capacity keeps growing.
But under the IEA's Sustainability scenario, which would see thermal power generation mostly phased out by the year 2100, the annual cost would only be $1 billion. Both figures assume a levelized cost of electricity from $0.10/kWh to $0.20/kWh.
In the U.S. and Europe, utilities' overall exposure to water stress will likely shrink as they pursue decarbonization strategies, replacing water-dependent plants with wind and solar parks. Some companies are also implementing water management and related investment strategies to reduce their exposure.
The researchers also point out that newer combined-cycle gas power plants, which are becoming more common, require less cooling than other thermal plants. That could mean heat-related curtailment at those plants is actually lower than estimated.
Power system trajectories and warming are also linked: If thermal plants are rapidly decommissioned, there would be less warming and therefore less curtailment.
"If we rapidly transition the electricity sector to non-thermal power sources like solar and wind, curtailment can be greatly reduced, although hydro power may face substantial future risk from reduced streamflow," the researchers wrote. "Our results highlight the double benefit from non-thermal electricity generation in a warmer world: less curtailment and fewer emissions."