Duke Energy Will Replace A Coal Generating Station With Battery Storage – CleanTechnica

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Duke Energy seems to be to the utility industry what Toyota is to automobile manufacturing. Both appear to be dragging their feet when it comes to embracing new technology. Toyota has been slow-walking the transition to electric vehicles for years. Through a subsidiary, Duke Energy built a grid-scale battery in Texas in 2013 using a grant from the Department of Energy, but the company never pursued other similar projects. Duke engineers tested various battery technologies in their laboratories and the company installed small systems for particular challenges, like an unusual zinc-air battery to power an off-grid station in the Great Smoky Mountains.

While utilities in California and Arizona were signing contracts for 100 MW systems to serve as cost-effective peak power sources, Duke Energy resisted the urge. Last year it installed its biggest North Carolina battery at the time, which provided just 11 MW at Camp Lejeune. But now, Duke Energy has seen the light. It will demolish the coal-fired Allen Steam Station west of Charlotte that has been producing electricity since 1957, the era of tail fin Cadillacs and other examples of automotive whimsy.

The Allen Steam Station originally featured five generating units that combined could crank out 1,155 megawatts of electricity. Four of those units have been shut down already, leaving just one 167 megawatt unit online. Duke plans to shutter that last unit by the end of this month in favor of cleaner, more efficient power sources. At that point, only five coal plants will be left operating in the state of North Carolina, but they are behemoths that provide 8,400 megawatts between them.

The retirement of a coal plant is not surprising, says Canary Media. That has been happening across the country since the shale revolution made gas radically cheaper than coal. Those methane-fired generating stations have stepped in to provide on-demand power in place of the outgoing coal generating stations. Now, in a first for the region, Duke Energy is investing in batteries to pick up some of the slack.

Duke Energy Is Thinking Big

To begin with, Duke will install a 50 megawatt/​200 megawatt-hour battery on 7.5 acres next to a substation across the street from the Allen Steam Station, with the goal of completing construction by the end of 2025. Once the old coal buildings are demolished, a 167 megawatt/668 megawatt-hour system will be built where the coal plant’s flue gas desulfurization system stands today. That installation, expected by October 2027, will match the instantaneous capacity of Allen Unit 1. Although, the battery will be able to maintain that power for only four hours at a time. Duke Energy could also add more battery storage onsite later.

These plans, which Duke first discussed with local reporters in late November, mean one of the biggest legacy utilities in the country is embracing the large-scale grid battery trend that has already swept through solar-heavy markets like California, Texas, and the desert Southwest. North Carolina currently ranks fourth in the nation for installed solar capacity, with nearly 10 gigawatts operating.

Duke recently asked for and received approval from regulators in North Carolina to construct 2,700 megawatts of energy storage by 2031. That’s a massive acceleration from basically zero and is more capacity than Duke expects to build for any other resources besides solar and combined-cycle gas plants. It’s a big lift, but locating installations at legacy power plants comes with a host of practical benefits. “Repurposing Allen’s existing transmission system and infrastructure enables a more efficient clean energy transition and lowers the cost for our customers, while maintaining our long-term commitment to Gaston County,” spokesperson Bill Norton told Canary Media.

Taking Advantage Of An Existing Grid Connection

An important consideration is that the Allen Steam site already has a grid hookup. In addition, the detritus from the existing coal-fired facility has rendered the land it sits on unfit for many other purposes. Prospects for redevelopment are limited by the large quantities of toxic coal ash present there, which Duke Energy is excavating and moving to double-lined landfills located onsite. In addition, Duke Energy could invoke a ​“generator replacement request” to streamline the grid interconnection process for the larger battery, since it exactly matches the last coal unit’s peak capacity. Such a request should have an easier time getting approved by the local grid operator than a completely new request would.

But this coal to battery switch isn’t a clean sweep for clean energy. These batteries are designed to cover four hours of peak power delivery, but then they run out of electricity, which could be a problem in a heat wave or a winter storm when residents are counting on electricity to keep their homes at a safe temperature. “For 24/7 reliability, we are also adding Lincoln 17, a natural gas combustion turbine in nearby Denver, N.C., that we take ownership of in December,” Norton noted. That 400 MW unit matches the power from the last two Allen units to retire.

Combustion turbines are designed to fire up quickly when needed for extreme demand — from 0 to 100 percent in less than 15 minutes, compared with 12 hours for the more than 60-year-old coal-fired generating units. That means the turbine probably won’t be running all the time, and when it does, the methane it burns will produce fewer carbon emissions than burning coal. The utility will also build more solar capacity in the region and expects to have surplus solar available to charge the new batteries. Norton stressed that Duke Energy will not rely on solar alone. It will recharge the batteries using whatever electricity is supplying the grid at the moment. Nevertheless, the Allen Steam Station makeover marks a new willingness from one of the country’s biggest utilities to add lithium-ion batteries to its roster of trusted, large-scale tools for delivering reliable power whenever it is needed.

It has taken Duke Energy a long time to embrace grid-scale battery storage, but here’s the thing: If this company, with its slow, measured approach to adopting new technology, is now on board, that means it has done it’s due diligence, dotted all the i’s, and crossed all the t’s. The only reason it would do this is if it knows for certain sure that this is the best and least expensive path forward it can take. That won’t go unnoticed by the other big players in the utility industry that may now feel they should also take another look at battery storage themselves. Facts and figures are one thing, but there is still the herd mentality factor. If Duke Energy is doing it, maybe other utilities will decide to do it as well, which will be an important step on the road toward a clean energy future.