Coal does, in fact, 'quit.' No form of energy is 100% reliable | Fact check

Kate S. Petersen, USA TODAY
·7 min read
Wind Power PerformanceFrom 2017 Wind Technologies Market Report

The claim: Unlike solar and wind power, coal 'does not quit'

A May 23 Facebook post (direct link, archive link) shows three images. One shows windmills spread across an agricultural landscape and is labeled "These quit working at -27C." The second shows solar panels and is labeled "These quit working at sunset."

The third shows an apparent coal mining operation and is labeled "Coal does not quit."

The post was shared more than 200 times in a month.

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Our rating: False

Solar and wind power do not produce energy all of the time, but neither do coal plants, according to energy system experts. Coal plants "quit" due to mechanical failures, weather events and for scheduled maintenance. Grid operators employ a variety of strategies to maintain constant power flow as weather-dependent renewables proliferate on the grid.

Coal does 'quit' for variety of reasons

When full and partial outages are accounted for, U.S. coal plants are offline about 12% of the time due to maintenance or unexpected failures, the National Renewable Energy Laboratory reported in January. There are multiple recent examples of coal plants failing during major weather events.

For instance, while the catastrophic power outages in Texas during the winter of 2021 were primarily caused by failures in the state's natural gas infrastructure, other forms of generation − including coal plants − also went offline due to cold temperatures.

More: Can we count on renewable energy? Four ways wind, solar and water can power the US

Coal plants also represented about 23% of the power plant outages during Winter Storm Elliot in 2022, contributing to rolling blackouts in the Southeastern U.S. In May 2022, coal plants unexpectedly went offline in Texas near the beginning of a record-breaking heat wave, according to the Institute for Energy Economics and Financial Analysis.

"As (the grid operator) began preparing for the early season heat wave, it was without almost 20% of its installed, supposedly dispatchable coal-fired generation," the institute reports.

That May, coal shortages also resulted in blackouts in India during a heat wave, AP reports.

A 2019 study that modeled temperature-related conditions on the PJM grid in the eastern U.S., predicted that both hot and cold weather events would increase the likelihood of unplanned coal plant outages. Unplanned outage rates would reach around 13% when temperatures drop to 5 degrees Fahrenheit (-15 degrees Celsius) and 14% when temperatures rise to 95 degrees Fahrenheit (35 degrees Celsius), the study concluded.

Grid operators account for renewable energy behavior

The Facebook post also states that solar panels stop producing after dark and wind turbines go offline at -27 degrees Celsius (-17 degrees Fahrenheit).

While researchers are exploring innovations that could allow solar panels to produce power after dark, the technology was not designed to produce electricity at night. And winterized wind turbines are only rated to around -30 degrees Celsius (-22 degrees Fahrenheit) − close to the figure given in the post − according to Paul Denholm, a researcher at the Grid Planning and Analysis Center at the National Renewable Energy Laboratory.

But grid planners know that.

"That's absolutely built into the way that the power system is designed," Denholm said. "We don't count on the wind blowing. The wind is used to offset the need for other − primarily fossil fuel − resources that are expensive. So the basic idea is you can save money by not buying as much natural gas to run your power plants and offsetting that generation with wind."

Fact check: False claim that wind turbine generators only last 3 to 4 years

As the amount of solar and wind power on the grid increases and fossil fuels decline, storage technologies will become increasingly necessary to keep power flowing as solar and wind switch on and offline, USA TODAY previously reported.

"You use the sun when it's available − either use it directly or you charge up batteries with solar," Denholm said. "Or when the wind is blowing more than you can use it, you charge a battery or other storage devices."

The stored power can then be used when renewables are offline or output is low.

Resource diversity − incorporating different types of renewable power onto the grid − will also be used to stabilize power flow on a renewables-dominated grid, Mark Jacobson, a professor of civil and environmental engineering at Stanford University, previously told USA TODAY. He noted that using wind and solar in tandem can be particularly useful.

"Wind and solar, which are both ... intermittent resources, are complementary in nature," Jacobson said. "When the sun is not shining, the wind is often blowing ... and vice versa. Thus, combining wind and solar on the grid smooths out the overall electricity supply over time."

Transmitting renewable energy from other places via transmission lines is another way to keep the lights on when local renewables aren't producing. Power can be moved from places where electricity is being generated to places where it isn't.

"It's not always windy in North Dakota," Denholm said. But "if the wind stops blowing in North Dakota, maybe it's blowing in Iowa. Maybe it's blowing in other locations."

When reached by USA TODAY, the Facebook user, Climate Change is Crap, acknowledged that coal plants go offline from "time to time for maintenance." The user didn't mention outages associated with weather or mechanical failures.

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This article originally appeared on USA TODAY: No single source produces power 24/7, experts say | Fact check