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Duke Energy is tapping tech wizards to convert coal plants into energy accumulators

Duke Energy, the massive utility that still relies on coal power for about 27% of its services, is partnering with a high-tech company out of Cambridge, Mass. to study whether the power provider can convert its retiring coal assets into energy storage systems.

The research, funded by the Department of Energy, will see whether energy storage technologies developed by Malta Inc., a startup company backed by investors including Bill Gates’ Breakthrough Energy Ventures, Facebook co-founder Dustin Moskovitz, and some strategic European industrial manufacturing companies.

Malta’s designing storage systems that can handle 100-megawatts of power for 10 hours using pumped heat exchanger technologies.

With Duke Energy, that kind of tech could be slotted in to existing coal plants that the company operates, starting with a plant in North Carollina.

The Malta system either stores electricity directly from a power plant, or from the wider utility grid by converting that juice into thermal energy. The heat is stored in molten salt while antifreeze-like solutions provide extremely cold temperatures.

“For utilities like Duke Energy to meet their net-zero carbon emissions goals, major advancements in technology are needed. The Malta system could be part of the solution by providing zero-emissions, load-following technology that provides reliable, resilient and around-the-clock power,” said Malta chief executive, Ramya Swaminathan, in a statement.

While the Duke study is focused on the utility industry’s need for 10–12 hours of storage, Malta said that its tech can store up to 200 hours of energy. That’s really really long duration storage.

Of course, Malta’s not alone in trying to find a solution for energy storage that’s not dependent on battery technologies.

Fortune wrote a great piece earlier this year listing the multiple companies that are tackling the energy storage dilemma.

Those are businesses like Energy Vault and Advanced Rail Energy Storage North America, which are both trying to use mechanical energy for long storage. In Energy Vault’s case that means using renewable power to lift huge one-ton blocks of cement that can then be dropped to unleash that stored energy as power. ARES North America uses a similar concept, but instead of big honkin’ bricks, the company has trains that it moves to store and discharge energy.

“Duke Energy is investing in innovation as part of our clean energy transformation plan to achieve net-zero carbon emissions by 2050,” said Regis Repko, senior vice president of Duke Energy’s Generation and Transmission Strategy organization, in a statement. “For years, Duke Energy has actively evaluated emerging technologies, and the Malta study marks the first time we will evaluate long-duration thermal energy storage. We expect the results to influence the future of energy and apply to our larger generation fleet.”

There are a few potential benefits that the Duke study hopes to address including: job retention and whether the company’s existing employees could transition to working on Malta’s system; whether the clean energy storage system could keep jobs and leave the property tax base unscathed; and whether long-duration storage could boost the adoption of renewables like solar and wind.

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