The H.A. Wagner plant delivers power near Baltimore. Where it once burned coal, it will soon discharge batteries. (Photo courtesy of Talen Energy)
Coal plants are shutting down across the U.S., but one in Maryland is switching to battery power in what appears to be a nationwide first. If successful, the transition could kick off a trend with big upsides for energy workers and communities located close to the plants.
Privately held power producer Talen Energy recently shuttered a coal-fired unit at the H.A. Wagner plant, part of its fossil-fueled fleet serving the mid-Atlantic PJM grid. Built in the 1950s, the facility generates electricity just down the Patapsco River from Baltimore. And it will keep serving that region with a new 20-megawatt battery, expected online within a year.
“This is the first of hopefully many unit transitions from coal to lower-carbon sources and battery,” said Cole Muller, who oversees Talen's fossil-powered fleet in the territory of regional transmission organization PJM. “It’s really about decarbonizing, ...investing in the communities and continuing to provide opportunities for our people.”
After that project, Talen plans to build a 1-gigawatt battery fleet in the next three to five years on its existing properties, using individual batteries as large as 300 megawatts.
It's no secret that coal plants have had trouble competing with cheaper renewables and natural gas. Unexpectedly low prices from PJM's latest capacity auction spurred a fresh wave of retirement announcements this month.
Talen promised in November to shut down roughly 5 gigawatts of coal capacity in the 2020s. But the company wanted more of a comprehensive strategy for this transition than just walking away from the plants.
“If you just retire it, you have a significant loss to both jobs and the tax base, and the communities at large,” Muller said.
Instead, Talen tapped battery developer Key Capture Energy to build the 20-megawatt system as a demonstration of the concept. That smaller size allows for a streamlined approval process, Muller noted. But the battery will act just like any other commercial power plant, bidding into PJM's markets for capacity, ancillary services and energy arbitrage.
Assuming that goes well, Talen can add up to another 115 megawatts of battery storage to fully utilize the coal plant's grid connection capacity.
That's a distinct advantage for developing batteries at an older power plant: The site has been cleared to export a certain amount of power to the grid, so there's less risk of having to pay for hefty network upgrades as developers must do at greenfield sites.
“If the system can handle 100 megawatts of coal, it can handle 100 megawatts of battery output,” Muller said.
Even if battery plants match the power output of the former coal plant, they can only go for a few hours before running out of charge. Operators will need to get comfortable with different kinds of market participation. Then again, batteries can fire up instantly, Muller noted, whereas a coal plant can take as much as a day to ramp up. That flexibility could become all the more valuable as new renewable generation and old plant retirements make the markets more volatile.
Another benefit of this switch is that many coal plants have a lot of space, as a legacy of the level of land availability when they were built many decades ago. The H.A. Wagner plant sits on nearly 500 acres right next to Maryland's largest city, Muller noted. Other Talen properties control even more acreage. That creates opportunities for battery or solar development without the need to acquire new land.
And switching from coal to batteries is easier from a resource perspective than switching from coal to gas because developers don't need to lock down gas supply, said Key Capture CEO Jeff Bishop.
"Pretty quickly, you can take the existing capacity and transition it to energy storage," he said.
Despite these benefits, coal-to-battery switching remains too nascent to be labeled a trend — yet.
"To my knowledge, this is the first battery at a coal plant anywhere," Bishop said. But, he added, "It’s becoming more understood with the folks that own [coal] generation that the transition is happening, and they can either be part of it or they will be left behind."
A much larger battery project is planned for the shuttered Wallerawang coal plant in New South Wales, Australia. But that's not expected until 2023.
Coal plants do come with remediation concerns, but with enough space, batteries needn't get installed directly on top of coal ash or coal piles. Since batteries emit no carbon emissions or air pollution onsite, the switch can improve air quality for communities surrounding the plants. That environmental justice benefit is especially impactful in dense urban areas.
Several companies have swapped gas generators for batteries, as Vistra opted to do on sites at Moss Landing and Oakland, both in California. New York City's Ravenswood gas-fired plant is planning to convert to batteries as well.
Developer Plus Power's Kapolei battery will take over grid stability duties from the last operating coal plant in Hawaii. But that battery won't be located at the same site, and the plants are owned by different companies, making for a different flavor of energy transition than in the Baltimore case.
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