From the Pacific Northwest to coastal New England, millions of Americans have endured sweltering temperatures in recent weeks, driving record energy consumption and offering a snapshot of emerging risks facing the nation’s power system.
While grid operators say the electricity system has largely held up so far this summer, Texas — where the grid remains under close watch after blackouts last year — saw record-breaking power demand during the latest heat wave and issued two conservation alerts to energy consumers in July. In some parts of the country, heat has also been linked to drought, creating challenges for hydropower and thermal plants that rely on water for temperature control.
“Many forms of thermoelectric generation, like coal and nuclear, that utilize water for cooling, can be heavily impacted by drought and hot water temperatures. The efficiencies of the plant also decrease if they’re not sufficiently cooled,” Kyri Baker, an assistant professor of engineering at the University of Colorado, Boulder, said in an email.
Like other extreme weather events, prolonged heat waves have become more common worldwide due to climate change. But analysts note that these events themselves can worsen greenhouse gas emissions, as power plants run more frequently to meet energy demand for air conditioning.
Extreme weather also has potential political ramifications for the transition to renewable energy. As aging fossil fuel plants retire, there needs to be enough new generation to replace them in order to keep the lights on in a warming world, said Paul Patterson, a utility analyst at Glenrock Associates LLC.
At the same time, extreme weather puts a spotlight on the existing energy system and its vulnerabilities, Patterson added. For example, many gas power plants lack on-site fuel storage. Heat can also strain energy infrastructure, creating the risk of malfunctions or pieces that melt or become inoperable.
“If there’s more pressure put on the system, any weakness is more likely to become more apparent,” he said.
The impacts of heat on the U.S. grid can vary significantly by region.
Over 11 million people in Washington, Oregon, California and Idaho were under excessive heat warnings as of Friday, according to the National Weather Service. Boston also was one of dozens of U.S. cities to hit record-breaking high temperatures in July, according to NOAA’s National Centers for Environmental Information. In New England, power plants in the region generally burn more gas and oil during summer heat waves, whereas renewables and nuclear tend to continue running “if available,” said Matthew Kakley, a spokesperson for ISO New England, which oversees the grid.
By contrast, solar output this summer has recently been higher than in previous summers in the Midwest — specifically, the 15-state grid region run by the Midcontinent Independent System Operator (MISO). On June 23, MISO experienced a new peak of 2,007 megawatts of solar capacity, driven in part by weather but also an increase in solar generation resources overall, said Brandon Morris, a spokesperson for MISO.
PJM Interconnection, the largest grid region by population covering portions of the eastern United States, approached its forecasted peak summer demand in July, but the region continues to have sufficient generation to keep power flowing. Recently, PJM has been able to support other grid regions by exporting electricity during the hot weather, said Jeff Shields, a spokesperson for the organization.
Still, heat waves can sometimes have “correlation effects” across states and grid regions, making it more difficult for grid operators to rely on their neighbors, the University of Colorado’s Baker said.
“If California is experiencing very high temperatures, it’s likely Nevada is too, and so there won’t be as much power in Nevada that can be sent to California,” she said. “California imports around 25 percent of their power, so they may be uniquely impacted by widespread heat.”
The impacts of heat waves on low-income households also are a growing concern for consumer advocates and the Biden administration. Yesterday, President Joe Biden announced six new initiatives aimed at lowering power bills in the face of extreme temperatures, including a program enabling those living in government-supported rental housing to sign up for community solar projects (Greenwire, July 27).
As the summer unfolds, here are three issues to watch for the U.S. power sector:
Fossil fuels vs. renewables
Unusually high temperatures erode the efficiency of power plants — including those that run on renewables, fossil fuels and nuclear power, experts said.
Operators of fossil fuel and nuclear plants, for instance, can have trouble cooling the sites because they have to use warmer water. And the wind can stop blowing during heat waves, causing turbines to produce less energy.
In extreme heat, transmission and distribution lines often start to lose more of their electricity in the act of moving it, as well.
Those factors can place an extra strain on grids that are already struggling to accommodate high demand from air conditioners. Typically, fossil fuel generation will also spike during a heat wave because of overall high power demand, with a parallel rise in greenhouse gas emissions.
“Emissions go up. Because we’re using more of every kind of resource — and in particular, the types of resources that create emissions,” said Alison Silverstein, an independent energy consultant in Austin, Texas.
That can happen even when some grids are running off a higher-than-normal percentage of renewable power — like in MISO’s region.
Increasing use of intermittent renewables on the U.S. grid doesn’t necessarily translate into diminished reliability during heat waves, though, said Silverstein.
“No one power source is perfect,” she said.
“We should be trying to diversify our electric resource portfolio in smart ways. And that doesn’t mean build huge amounts of wind and solar only. It means more storage and demand response,” among other resources, added Silverstein.
Those preparations for future heat waves may also dovetail with cutting emissions on the grid, said Erin Baker, faculty director of the Energy Transition Initiative at University of Massachusetts, Amherst.
Energy storage and demand-side response programs tend to be of high value for the grid during heat waves, because they can help deal with extreme peaks in power demand, she said. Those same tools also help balance out power supply from intermittent technologies like wind and solar.
“There’s a kind of complementarity,” she said. “Planning for heat waves and planning for a cleaner grid are similar.”
However, new sources of consumption — including through projected population increases in some regions — are complicating the effect of heat waves.
For example, one source of uncertainty for the grid during high temperatures is crypto mining.
That energy-intensive process, in which computers “mine” the value of a cryptocurrency by solving complex puzzles, has sparked worries in the past after an influx of miners caused electricity demand to spike.
Those worries could resurface during this summer or in summers to come, observers say.
After China banned the practice earlier this year, crypto miners looked elsewhere. About 37 percent of global “hashrate,” which refers to the amount of computing power, now stems from operations in the U.S, according to the Cambridge Centre for Alternative Finance.
In Texas, for example, 27 gigawatts of “flexible” load from large consumers — including but not limited to crypto miners — are waiting to interconnect over the next four years, according to the Electric Reliability Council of Texas (ERCOT), the state’s main grid operator. A little over 1 gigawatt is currently interconnected or has been approved.
Joshua Rhodes, a research associate at the University of Texas, Austin, referred to reports that as much as 17 gigawatts of new load could come from crypto miners, although that struck him as suspiciously high.
“I’m taking the numbers with a grain of salt,” he said.
But he added that if the estimates were true, the ERCOT grid could see itself overwhelmed with new electricity demand — something that would be especially fraught in an era of frequent heat waves.
Ed Hirs, an energy fellow at the University of Houston, said that crypto mining companies “will prove to be the tapeworm of ERCOT.”
If the companies continue to flock to Texas, Hirs said in an interview, they “will eventually be such a big component of demand on the ERCOT grid that the grid’s going to have to pivot to service them as a priority.”
Insufficient maintenance of generating equipment could be a nearer-term threat to the grid, Hirs added. After ERCOT canceled scheduled maintenance outages in May and June, it’s unclear how many thermal generation plants actually underwent their planned annual maintenance, an issue of particular concern for plants that are nearing their retirement ages.
Spokespeople from ERCOT said that an advisory body — the Large Flexible Load Task Force — would help grid operators maintain reliability while incorporating big new sources of demand from crypto miners.
“ERCOT expects sufficient generation to meet forecasted demand,” said the spokesperson, Trudi Webster, in an email.
Lee Bratcher, a spokesperson for the Texas Blockchain Council, said his group was expecting a more modest amount of crypto load to come online — around 3 to 5 gigawatts by the end of 2023.
“Bitcoin mining is actually part of the solution to challenges with the daily duck curve of power demand,” he wrote in emailed comments. Miners could turn off power consumption when demand is high on the grid, while also incentivizing more power generation, he argued.
“They are a flexible load like we have never seen before. A demand-side battery if you will,” wrote Bratcher.
Another issue is whether the pace of transitioning away from fossil fuels will parallel needs on the energy consumption side in the years ahead.
In New York, for instance, energy policymakers are trying to plan out how to dramatically phase down fossil fuel use in line with state climate laws, while ensuring that air conditioners can keep humming during hot spells.
The New York Independent System Operator (NYISO) warned this summer that reliability margins are already close to reaching their minimum requirements in some parts of the state. If those margins are depleted, said NYISO in a July 1 letter to climate planners, it could put the grid at risk of power outages.
The state’s Climate Action Council, which is the chief planning body for compliance with New York’s climate laws, has highlighted the importance of reliability during heat waves as well.
A draft scoping plan — a blueprint for the state’s energy future — released last year has linked the grid’s reliability to heat-related deaths, saying that air conditioning is the “principle means to prevent” them.
“By improving the reliability of the grid, the State can prevent millions of dollars in damages and prevent premature mortality,” the document reads.
Drought conditions gripping the U.S. are shining a bright light on a severe and emerging risk to the nation’s long-term power supply: water scarcity.
“This nexus between water, energy and climate is a very tight one, these connections are very tight, and the problems are going to get worse as climate change continues to accelerate and as long as we rely on water-intensive fossil fuel plants,” said Peter Gleick, a water and climate scientist and co-founder of the Pacific Institute, a leading nonpartisan water-focused think tank.
The danger is most glaring on the parched West Coast where California, plagued by climbing temperatures, saw hydroelectric generation fall 48 percent below a 10-year average last year, and output was likewise curbed across the Pacific Northwest. Almost half of the Pacific Northwest has been experiencing worsening drought, made worse by waning precipitation in the winter that exacerbated areas already hit by dry conditions in 2021.
The current dry spell — considered one of the worst on record — will likely take a bigger chunk of California’s hydropower out of commission, added Gleick. Hydropower is only likely to produce about 7 or 8 percent of the state’s electricity supply this year instead of typically more than twice that, said Gleick, adding that “bad things result” when that happens.
“Consumers pay much more for electricity because hydropower is among the cheapest of our energy sources, we burn more natural gas, which is typically the next marginal source of energy for us,” he said. “That costs more money and ironically increases greenhouse gas emissions and worsens the climate problem.”
But the risk isn’t isolated to the West Coast.
Federal scientists last year warned that water supplies to coal and nuclear plants could dwindle in a warming future. Coal, natural gas and nuclear facilities rely on freshwater to cool and condense steam that drives power turbines, and their operations can be curtailed if water levels in reservoirs, lakes or rivers drop too low, or discharges of heated water from plants raise water temperatures too high (Energywire, June 28, 2021).
In May, a report warned that drought conditions in the Missouri River basin could affect operations of gas, coal or nuclear plants in the Southwest Power Pool that rely on the river for cooling water supplies (Energywire, May 19).
Problems are also escalating in Europe. In France, Électricité de France SA was forced to reduce or halt nuclear output to ensure water used to cool the plants doesn’t harm the environment when it’s put back into waterways (Energywire, July 6). Severe drought has also reduced hydropower output in Italy, while low river levels have limited shipments of coal to power plants in Germany, even as the country scrambled to shore up declining gas flows (Climatewire, July 21).
But experts say the United States, given its massive geographic footprint and sprawling river systems, is somewhat buffered from the worst effects of the drought for now.
“In Europe, you have smaller rivers, the catchment of the rivers are very small compared to the United States and when you have a drought like this, the levels go down so much you have to curtail power, the same for India and other regions,” said Lorenzo Rosa, principal investigator at the Carnegie Institution for Science in the Department of Global Ecology at Stanford studying climate solutions and sustainability.
“One advantage of the U.S., excluding the West like California and Arizona, is that you have such a big catchment that you’ll likely have in the near future water for energy,” he added.
But Rosa said competition for water is increasing, noting that agriculture clocks in as the largest user of ground and surface water in the U.S. As time passes, he added, temperatures will increase with climate change, as will evaporation and changes in precipitation, creating more aridification in the West and increased downpours in the East.
Those shifts, he said, highlight the need for the power sector to plan accordingly, to consider the water needs of the location of new power plants, including for carbon sequestration or emerging technologies like hydrogen.
“You can’t think about energy systems without thinking about water availability, and that includes the energy transition,” said Rosa.
While current heat waves are focusing attention on the power grid and the mix of electricity that flows through it, it is less clear what that means for the politics of renewables and fossil fuels.
“What these heat waves are doing is, they’re bringing more attention to energy systems and the power grid,” said Melissa Lott, director of research at Columbia University’s Center on Global Energy Policy. “People are in the middle of a hot summer and asking questions about whether they can rely on their power.”
On one hand, heat waves — particularly if they result in power outages — can increase public support for emissions-cutting policies, said Lott.
But economic questions often take precedence in the minds of voters, according to many polls.
“The big thing that people are thinking about is, what’s their energy bill going to look like this month, next month,” said Lott.
Extreme weather’s effect on low-income customers is a key focus for consumer advocates as heat stretches the power grid’s limits.
During heat waves, low-income people may be wary of running their air conditioners too much, forcing them to choose between keeping comfortable and spending even more on their power bills, said Jenifer Bosco, a staff attorney at the National Consumer Law Center.
Even before the start of the summer, electricity costs were rising, largely because of increasing natural gas prices. In addition, not all states have policies in place prohibiting service disconnections during heat waves, Bosco said.
Adrian Shelley, director of the Texas office of Public Citizen, said without improvements to the grid, heat waves fueled by climate change “will continue to set summer peak demand records and lead to more frequent calls for conservation.”
“There’s a lot we can do to address inequity, from bill pay assistance to access to energy efficiency programs for low-income residential customers,” Shelley said in an email.
In addition to addressing rising bills, one question for utilities and regulators is how to effectively encourage people to use less energy.
Last month, ERCOT issued conservation appeals for July 11 and July 13, calling on “Texans and businesses to voluntarily conserve electricity” for several hours. Texans have responded to those calls, according to a spokesperson for ERCOT.
“On Monday July 11, between 1:56pm-2:00m, of the conservation appeal, we saw customers take action and almost 500 [megawatts] of load dropped off,” said ERCOT’s Webster in an email.
Still, Bosco noted that not all households may be able to cut their power consumption.
“We need to be sure to recognize there are a lot of households with elders, low-income families and households with small children where it might not be a great solution to allow your house to get warmer than it should during times when you might be home,” she said.
Rhodes, the University of Texas research associate, said that while ERCOT has made calls for electricity conservation before, those requests to conserve power are getting more attention since the devastation of widespread power outages tied to Winter Storm Uri in February 2021.
“Asking people to use less a few times can be quite a bit cheaper” than building more power plants, Rhodes said, noting that as more people move to Texas, that increases the number of people using air conditioning.
If more parts of the country have to install air conditioners in homes, that increases demand on the grid, he said.
“Most other grids, besides Southern grids that are kind of … already air conditioner-heavy, are winter peaking and so they presumably have room in the summer to be able to provide more power, since they’ve traditionally provided the most power in the wintertime,” Rhodes added.
In some states, utilities are exploring new ways to encourage less power consumption when the grid is strained.
Duke Energy Corp., for example, is developing new rate structures that incentivize less consumption at targeted times, “providing an incentive through lower rates at times of lower demand to encourage shifting their use,” said Sally Thelen, a spokesperson for the company.
One way that policymakers and utilities could help consumers and ensure reliability is by investing in energy efficiency, said Mike Jacobs, a senior energy analyst at the Union of Concerned Scientists. Over the years, however, the benefits of energy efficiency have often been overlooked, but it becomes increasingly important as temperatures rise, Jacobs said.
“When you’re trying to keep your house 30 degrees different from the outside temperature, the insulation is a bigger part of the whole energy supply. You get a bigger effect for it,” Jacobs said.
Reporters Miranda Willson, David Iaconangelo, Hannah Northey, Carlos Anchondo and Camille Bond contributed.