Power Grid Reliability Jeopardized as Coal Plants Close Faster Than Replacement Renewables Open

Wind turbines operate at a wind farm near Whitewater, Calif., on Feb. 22, 2023. Mario Tama/Getty Images

As the United States rushes to reduce carbon emissions, energy executives worry reliability of the power grid is in peril. That concern was repeated numerous times Thursday in Pittsburgh during a joint hearing of Pennsylvania and Ohio state lawmakers about the PJM electric grid.

PJM coordinates the movement of wholesale electricity in all or parts of 13 states and the District of Columbia to assure electric reliability—that the power is always there when desired. It is one of seven regional transmission organizations or independent system operators throughout the United States. There are two others operating in Canada.

More than 65 million people are served by PJM across nearly 369,000 square miles.

In recent years, coal, oil, gas, and nuclear power generators have been retiring at a rapid pace due to government and private sector policies, as well as economics, a PJM report said.

Three Mile Island Nuclear Generating Station in Pennsylvania shut down in 2019. Pennsylvania’s largest coal-fired power plant, the Homer City Generating Station, closed in July. Conemaugh Generating Station and Keystone Generating Station, both coal-fired Pennsylvania electric generators, are slated for closure by 2028. And Brandon Shores power plant near Baltimore seeks to close in 2025.

“The recent retirement of Homer City Generating station coal fired units removed 2,000 megawatts of capacity from the grid,” Steve DeFrank, chairman of the Pennsylvania Public Utility Commission, testified at the hearing. He added that the loss of Conemaugh and Keystone represents a loss of 3,400 megawatts of capacity, and Brandon Shores is another 1,300 megawatts.

PJM is facing significant headwinds with these retirements, he said.

More Renewables and More Demand

As electric generation retires, replacement generation is working through the permitting process. Due to government incentives, new requests to connect to the PJM grid are almost exclusively—approximately 98 percent—coming from renewable resources and batteries, comprising 43 percent solar, 16 percent wind, 23 percent from storage resources, and 16 percent from hybrids of batteries co-located with renewables, primarily solar, according to PJM.

The energy transition is happening as the demand for electricity is predicted to soar. President Joe Biden aims to require that 60 percent of new car sales be electric by 2030 and 67 percent by 2032. The regulations also push electric stoves and electric heat—all giving the illusion that these decisions create immediate benefit to the environment. But electricity comes from a blend of power sources.

“There is a concern about a supply crunch at end of decade,” testified Asim Haque, senior vice president for state and member services for PJM. “Increased demand, decreased supply, and supply not coming in quick enough to replace the supply that’s leaving the systems—fundamental supply/demand issues.”

Electricity is generated by coal, oil, gas, nuclear, hydro, wind, and solar companies that sell power through a series of three PJM markets, the “day ahead” market, the “real time” market, and the “capacity market.” The capacity market promises to provide power three years in advance and the real time market is responding to current conditions. Is it dark and still? When solar and wind are not available, coal, gas, and nuclear are always ready. Did the temperature drop suddenly? When everyone cranks their heat up at the same time, PJM’s real time market calls up the most reliable power.

As we transition to using more renewables—solar and wind—the risk to reliability is evolving, Mr. Haque said.

“A solar resource, while being able to perform extremely well during the summer, may not perform as well during the winter. How should the market evolve to account for that engineering fact?” Mr. Haque said.

Winter Weather Demand

During winter storm Elliot during the Christmas holiday weekend of 2022, a sudden temperature drop and blustery winds caused widespread generator failures and frozen natural gas supplies as electricity demand rose in Pennsylvania. There were power outages for some of PJM’s neighboring utilities.

PJM fuel mix during winter storm Elliott in December 2022. Courtesy of Rachel Gleason

“PJM operators had to implement multiple emergency procedures and a public appeal to reduce energy use to maintain reliability in its footprint,” Mr. DeFrank said. “Aside from nuclear resources, all generator types were significantly affected by the winter storm.”

But as long as PJM keeps the real time demand covered, the lights stay on, and the power keeps flowing. PJM is constantly adjusting the real time mix to prevent the risk of a blackout. Currently, fossil fuels make up the majority of the real time power blend. A pie chart on the PJM website shows the current blend of resources providing power.

Reliability challenges are intensified when electric generation is retired, and new generation is not keeping pace with what is being retired.

“It’s not just that the new generation is not keeping pace with the retired generation one over one, but it’s also because of the intermittent nature of the new generation,” testified Diane Holder, vice president of entity engagement and corporate services for Reliability First, a company that looks for risks and solutions to electric reliability issues.

More renewable megawatts, about 3 to 1, are needed to replace retiring fossil fuels to maintain reliability, according to earlier testimony.

“Policies that ensure a diverse portfolio of generation types throughout the transition, as well as policies that allow the use of environmental waivers when needed to maintain reliability, will really help position us well for a reliable transition,” Ms. Holder said.