Why are blackouts looming? Blame extreme weather, not wind and solar

Extreme heat, ongoing drought and wildfire threats are putting power grids across the Western U.S. at increased risk of rolling blackouts this summer. This finding, announced by the country’s primary grid monitor last week, has been backed up by analysis and by real-world events in California, Texas and the upper Midwest over the past month.

But while this increased risk coincides with the rapid shift from fossil fuels to renewable energy, it is not caused by the shift, grid experts say — despite some claims to the contrary. The main culprit for reliability problems is climate change and the extreme weather it causes.

A growing amount of solar and wind power does complicate grid-balancing efforts. But traditional fossil-fueled power plants, which contribute to climate change, are as vulnerable to this extreme weather as the cleaner and cheaper resources that are replacing them — if not more so.

These challenges are laid out in the 2022 Summer Reliability Assessment released last week by the North American Electric Reliability Corp., which tracks grid conditions in the U.S. and Canada. The report warns of ​“high risk of energy emergencies during peak summer conditions” across much of the Midwest grid served by the Midcontinent Independent System Operator (MISO), and heightened risk across the U.S. West.

The assessment came after most of MISO’s northern and central regions failed to secure enough generation capacity to meet predicted summer loads in a regionwide auction last month. That shortfall of 1,230 megawatts is compounded by damage from a December tornado to a major transmission line capable of carrying about 1,000 megawatts from MISO’s southern region, with repairs not expected until late June.

Texas grid operator ERCOT, which is still working on weather-proofing its grid after the massive blackouts during Winter Storm Uri in February 2021, asked customers to conserve electricity earlier this month amid record-breaking heat and the unexpected failure of six gas-fired power plants.

And California, which has faced tough summer grid conditions amid heat waves, drought and wildfires over the past two summers, is now planning to shore up grid reliability with more than $1 billion for batteries, energy efficiency and demand-response incentives and more than $5 billion for diesel backup generators and aging gas power plants.

Some grid regulators blame these conditions on what they characterize as a too-rapid transition from fossil fuels to renewable energy. At a meeting of the Federal Energy Regulatory Commission last Thursday, Commissioner Mark Christie, a Republican, said the new NERC report and a similar report from FERC staff provide ​“clear, objective, conclusive data indicating that the pace of our grid transformation is out of sync with the underlying realities and physics of our system.”

But FERC Chair Richard Glick, a Democrat, disputed that view in a press conference after the meeting. ​“The extreme weather we’re seeing doesn’t just impact wind turbines or solar panels,” he said. ​“We’re talking about everything” that supplies power to the grid.

Commissioner Allison Clements, also a Democrat, pointed out during the FERC meeting that extreme weather is stressing the power grid in ways it has never been stressed before. ​“This is now a yearly cycle, and we are always bracing for extreme weather without the time to catch our breath.”

Extreme weather is the ​“wild card” for risky grid conditions

Though Christie claimed that NERC’s summer assessment supports his view that the pace of the clean energy transition is endangering the grid, the assessment actually highlights how extreme weather is the main factor driving the risk of ​“temporary operator-initiated load shedding” — rolling blackouts, in common parlance — this summer.

The report identifies the chief risk factors in northern and central MISO territory and in Texas as more extreme temperatures and resulting spikes in demand for electricity and potential power plant failures, as well as low wind conditions.

Widespread drought across much of the West is reducing hydropower output, an important carbon-free resource, the report states. But drought is also reducing water flows in the Missouri River Basin used to cool fossil-fueled plants and nuclear generators in the region of grid operator Southwest Power Pool, it points out.

Meanwhile, wildfires could cause risks to transmission links within and between grid regions, NERC warns, as happened last year to a power line carrying electricity from Oregon to California.

As Paul DeCotis, senior partner at consultancy West Monroe, told Canary Media, ​“The wild card is the extreme weather events. That’s what’s going to cause strain on the system.”

He said that the regions of the U.S. West are not falling particularly short on the capacity needed to meet what grid planners would have traditionally considered ​“normal” summer weather patterns. ​“There is sufficient generating capacity, sufficient reserves and sufficient transmission capability to move power between selected grid regions,” he said.

Nor is NERC projecting risks of ​“catastrophic grid failure” like what happened in Texas last winter, he said, but rather ​“rolling brownouts,” or deliberate and controlled outages to certain portions of the grid, which ​“are not uncommon on high peak summer days.”

The problem is that increasingly abnormal weather is raising the risk that these deliberate outages will happen more often, he said. That’s not something that can be blamed on the shift from fossil fuels to renewables.

While coal plants have been closing down at a more rapid pace over the past few years, and solar and wind power resources have become the primary type of new generating capacity being added to the grid, this isn’t an underlying cause of grid instability, he said.

“People blame wind and solar for brownouts,” DeCotis said. ​“That’s not the case.”

He noted that grid planners’ short-term and long-term outlooks incorporate forecasts of the weather patterns that determine how much solar and wind power will be produced. While some of the weather patterns can lead to grid challenges — for example, the ​“duck curve” of solar power that floods California’s grid during the day and fades away as the sun goes down — those are predictable effects, he said.

Fact-checking reliability data for power plants

Wind and solar power are not more susceptible to extreme weather events than thermal power plants, said Charles Teplin, a principal in nonprofit think tank RMI’s Carbon-Free Electricity program. (Canary Media is an independent affiliate of RMI.)

“If you look at what’s actually failed on the generator side due to extreme heat or weather, it’s mostly fossil plants,” he said. He pointed to the example of Winter Storm Uri, during which low temperatures froze fossil gas wellheads and pipelines and the cooling systems of nuclear and coal-fired power plants.

“That doesn’t mean that wind and solar have been perfect,” Teplin said. Extended periods of calm winds or cloudy skies can reduce renewable energy output. Some wind turbine blades froze during Winter Storm Uri. NERC’s report cited the risk of grid disruptions from lightning strikes or wildfires that can cause solar-farm inverters to trip offline, increasing grid instability.

Still, ​“that’s small potatoes compared to what’s been going on with gas capacity,” Teplin said. 

If anything, thermal generators that rely on ample flows of fuel and water for cooling are more susceptible to extreme temperatures than are solar panels, which don’t have moving parts, and wind turbines, which don’t require cooling, according to a 2019 analysis from the Natural Resources Defense Council.

“Fossil generation is not as dependable as it has been given credit for,” said Rob Gramlich, president of consultancy Grid Strategies. In fact, thermal generators run the risk of failing simultaneously with one another in ways that can exacerbate grid risks, he said.

That problem is highlighted in a 2018 study by professors at Carnegie Mellon University and John Moura, NERC’s director of reliability assessment. Simply put, power plants of the same type tend to fail for similar reasons, said Jay Apt, a professor at Carnegie Mellon and co-author of the report.

“The effect is quite serious at low temperatures” that can freeze up fuel pipelines and power-plant cooling systems, Apt said in an email. Fossil gas plants in the territory of PJM, the country’s largest grid operator, are five times more likely to fail at 5 degrees Fahrenheit than at 30 degrees, Apt and doctoral student Luke Lavin pointed out in a 2021 opinion piece in The Washington Post examining that year’s grid crisis in Texas.

This chart from Texas grid operator ERCOT shows how extreme cold can layer risks on gas-fired power plants.

High temperatures yield similar, if less pronounced, correlated failure risks, Apt told Canary. Hotter weather raises the temperature of the water that’s used to cool coal and nuclear plants, making it less effective and forcing operators to run the plants at reduced settings, he said. Fossil gas turbines also lose efficiency when using hotter, less-dense air that contains less oxygen to burn.

Apt highlighted that these risks of correlated power-plant failures are ​“only part of the story” behind NERC’s assessment of summer grid risks. But even so, they indicate a flaw in how grid operators now calculate grid risks, he said.

Current planning methods ​“assume that every generator fails independently of any other,” he said. ​“Because many generators fail at extreme temperatures, that math is wrong.”

Solutions to grid risks: Planning for diversity in technology and geography

The tendency of similar types of power plants to fail at the same time has serious implications for grid planners, according to a November 2021 report by Michael Goggin, vice president of consultancy Grid Strategies, and Derek Stenclik, co-founder of power system analytics firm Telos Energy. The paper highlighted the correlated outages of gas plants that caused the February 2021 blackouts in Texas as one example of ​“a key reliability risk” that may be missed by current methods of assessing resource adequacy, a process that entails determining what mix of generation capacity can keep the risk of major grid shortfalls within reasonable limits.

Summer and winter grid peaks are no longer the only periods of grid risk that need to be planned for, the report states. Power plant operators have traditionally targeted the spring and fall ​“shoulder months” for taking plants offline for maintenance.

But as FERC Commissioner Clements said in last week’s meeting, Texas’ record-breaking heat, unexpected power plant outages and the resulting gap between electricity supply and demand this month indicate that ​“there are no longer shoulder months where we can take a deep breath and allow for regularly scheduled maintenance [to prepare for] for next season’s challenges.”

Meanwhile, the rising levels of variable solar and wind power are creating their own patterns of energy surpluses and deficits that need to be planned for, Goggin and Stenclik state in the report.

Expanding transmission networks can help increase the ​“geographic diversity” of resources, the report points out, by allowing power to be delivered to regions that are facing weather-related shortfalls from regions that are not.

Transmission projects are costly and hard to build, and the number of longer-range projects that are being successfully completed has shrunk in the past decade. But efforts are underway at the federal, state and regional levels to assess transmission’s value in improving grid capacity and reliability as a way to engage more utilities and state regulators to support building more transmission infrastructure.

Local resource diversity can also mitigate the risk of weather-related impacts on thermal or renewable generation, Goggin and Stenclik note in the report. Batteries can store several hours’ worth of renewable energy for use later in the day, and demand-response programs that pay customers to reduce energy use can relieve grid stress at key moments.

FERC’s new summer assessment notes that last year, during ​“the warmest summer on record,” demand response provided about 2,500 megawatts of relief for MISO and about 800 megawatts of load reduction for California grid operator CAISO. Similar levels of demand response and energy conservation may be needed again given forecasts predicting a similarly hot summer this year, the assessment notes.

This kind of integrated, long-range grid planning is going to be critical as the grid becomes the source of energy for electric transportation, heating and other loads that will rely on clean electricity to decarbonize, said Daniel Brooks, vice president of integrated grid and energy systems for the Electric Power Research Institute, a utility-funded nonprofit research group.

“It’s really important that we change our planning processes to provide a better assessment of what the risks are of a changing climate and the future environment in which the grid is going to operate,” he said. ​“Our existing resource-adequacy planning processes weren’t really designed for considering when these extreme weather events align with this changing resource mix.”

EPRI has launched an initiative with utilities, regulators and grid operators to develop modern methods to deal with these problems, Brooks said. That work starts with using climate and weather forecasts to determine future grid vulnerabilities and then translating that to the potential impacts on society.

That, in turn, can allow grid planners to ​“prioritize investments across the power chain,” he said. ​“It’s not just going to be clean generators,” he added. ​“It may be that a transmission line may be the best solution, or a microgrid, or community resiliency.”