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HERMITAGE — Officials with the Hermitage Municipal Authority are considering storing power in addition to its primary mission of treating waste.

The authority, also known as the Hermitage Food Waste to Energy and Wastewater Plant, is negotiating with Viridity Energy Inc. of Philadelphia for a contract to store about four batteries.

Each battery, which is about the size of a tractor trailer, can store up to 2.2 megawatts of electricity. All four of the batteries could hold up to 8.8 MW, said authority Superintendent Tom Darby.

“By comparison, the biggest batteries on the eastern seaboard can store up to 20.2 megawatts,” said consulting engineer Jason Wert, of RETTEW Inc., Wednesday at the authority’s meeting.

Viridity will have to get approval from PJM Interconnection — which owns the power grid in Pennsylvania, New Jersey and Maryland — for storing the batteries at the wastewater plant. The municipal authority would have to file a building permit with the City of Hermitage.

The authority and the company would also have to negotiate a lease agreement for the storage of the batteries, which Darby said could include giving the authority the ability to use the batteries as a backup energy source in the event of a power outage.

“The batteries could act as a backup to the entire Shenango Valley,” Darby said.

Hermitage Municipal Authority gave Viridity approval to submit a permit request to PJM, though Darby said he isn’t sure how long it will take to complete the application process.

The batteries aren’t Hermitage Municipal Authority’s first foray into power. The plant is in its fifth year of converting food waste into methane.

When the program began, Darby said the plant started with about 50 tons of food waste a month. That figure has now grown to 400 to 500 tons a month. The food refuse emits methane, which is turned into electricity that the authority can sell back to the power grid.

The authority is credited for $20,000 to $25,000 worth of electricity produced, which helps offset the plant’s power bill. Mercer County-based companies such as Dean Dairy and Joy Cone provided some of the initial food waste, but Darby said the authority now receives refuse from as far away as Erie County and the Akron, Ohio area.

“We can take refuse from as far away as people are willing to haul it,” he said.

Like David L. Dye on Facebook or email him at ddye@sharonherald.com.