End of an era; Duke Energy replaces Gaston coal plant with batteries - Business North Carolina

Duke Energy shuts down its last coal-fired unit at Allen Steam Station in Belmont on Tuesday, Dec. 31, and will soon construct its largest grid battery energy-storage site on a small piece of the 943-acre property along the Catawba River, fewer than 20 miles west of Charlotte.

“We’re not only retiring the Allen plant, but we’re building new resources here,” says Duke Energy spokesman Bill Norton.

First, Duke plans a 50-megawatt, four-hour lithium-ion battery energy storage system on 8 acres at an electrical substation across the street from the Allen plant. Construction is expected to start in January and be complete by the end of 2025, becoming Duke’s largest battery system, says Norton. It will be able to supply about 50,000 homes with electricity for four hours.

A second, much larger battery energy storage system will be built on 10 acres near the location of the Allen Steam Station’s smokestacks. This 167-megawatt, four-hour battery storage system is expected to be ready by late 2027 and will be more than five times larger than Duke’s current largest battery system.

The 167 megawatts match the production level of the last of five coal-fired generators at the Allen plant, which allows Duke to repurpose its transmission infrastructure. The batteries at both sites will store solar and nuclear energy generated elsewhere, which Duke can use to offset peak demands.

Duke expects the battery projects to cost several million dollars but does not have a final cost estimate. The federal government will pay about 40% of the cost through Inflation Reduction Act funds, Norton says.

Reducing carbon emissions

The battery projects are occurring as Duke demolishes its Allen Steam Plant, and pushes to eliminate its five remaining coal-fired plants by 2035. Duke is working to comply with a 2021 state law that requires a 70% reduction in carbon emissions by 2030 (with 2005 as the baseline year), and carbon neutrality by 2050.

The Allen plant first generated electricity for the Carolinas 67 years ago. Dwight Eisenhower was president; the first walk on the moon was still a dozen years away. The company was then known as Duke Power.

Duke has been shutting down Allen’s five generator units, built between 1957 and 1961, since 2021.

Duke shut down three Allen units in 2021 and a fourth unit this past September. The remaining unit was fired up only 11 times in the last year in anticipation of high-energy demands on either extremely hot- or cold-weather days, says Jeff Flanagan, a general manager for dispatchable generation for Duke Energy plants in the western fleet, including Allen.

“It’s bittersweet,” Flanagan says of the plant’s closing. “We know it’s the right time, it’s the right transition, but it’s a little sad to walk away from it.”

Coal is more expensive and the Allen plant has outlived its economic advantage, says Flanagan. “There’s a lot of equipment on site that’s the last of its kind,” he says. “Spare parts are increasingly difficult to find. Finding expertise to work on the equipment is increasingly difficult to find.”

In its heyday, Allen operated 24/7, and employed around 160 people. The five Allen units could produce 1,155 megawatts of electricity, enough to power almost 1 million homes. About 45 Duke employees work at Allen now. Flanagan says about half of them will move on to other jobs with Duke. The rest will retire with the unit.

Pre-demolition work at the site began months ago and the iconic five red-and-white striped smokestacks are expected to start coming down in February. Demolition crews will use a hydraulic process and start at the top of the smokestacks to bring them down one at a time, about 20 to 30 feet per day. Each stack will take a couple of months to complete with the demolition likely to be complete by the fourth quarter, Norton says

Coal ash

Duke was limited in what it could do at the Allen Steam Plant because of the 20 million tons of coal ash present. A byproduct of burning coal, coal ash contains contaminants like mercury, cadmium and arsenic and without proper management, it can pollute waterways, groundwater, drinking water, and the air. Some coal ash can be recycled into products like concrete and gypsum wallboard.

Duke considered taking the coal ash off-site but eventually won state environmental approval to create four double-lined landfills at Allen and bury it there. The lined landfills will require much of the land at the former Allen Plant and will limit construction because the landfill lining must remain intact. Even solar panels over the landfill area would be cost-prohibitive, says Norton.

“That’s really taking the vast majority of the site and batteries were the most compact resource to take advantage of,” Norton says of the landfills.

Duke has already excavated about 1.4 million tons of coal ash and has about 18.5 million more tons remaining. About 100 contract workers are doing the work, which will take until 2038. The landfills must be 5 feet above the groundwater table. In addition to lining the bottom of the landfill, the top of the landfill will include about a foot of clay and a foot of synthetic material.

Once covered, native grasses will be planted on top, says Norton.

“The goal is to make it look like a power plant was never here,” says Norton.

Duke will also be required to monitor drinking water and water quality of the Catawba River and Lake Wylie for 30 years, says Norton. Duke did not provide an estimate of the cost for creating the coal ash landfills.