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About the Tunnel Battery Energy Storage System

The Tunnel Battery Energy Storage System (BESS) project, being developed in collaboration with New Leaf Energy, will replace the Tunnel Jet Gas Peaker, which was decommissioned in 2023. The 16+ MW battery project will bring improved energy services and new benefits to the grid by charging when surplus energy exists and dispatching that energy during times of high demand. The project will also reduce GHG emissions by delivering a clean alternative to fossil-powered peaking facilities.

The Tunnel BESS project will be co-located with FirstLight’s existing Tunnel Hydro facility, highlighting the opportunity to pair batteries with hydropower to increase renewable energy supplied to Connecticut communities. The project will sit directly adjacent to the Tunnel substation and will comprise approximately 1.9 acres, with 1.4 acres developed for the battery and associated infrastructure.

Community Benefits

FirstLight’s repowering of the Tunnel Jet Gas Peaker to a Battery Energy Storage System mitigates harmful carbon emissions in an environmental justice community while maintaining generation capacity and delivering new benefits to the New England grid. The project avoids disruption to the local community by repurposing the same footprint as the Tunnel Jet Gas Peaker and utilizing the existing interconnection point and substation infrastructure used for the decommissioned peaker.

The Tunnel BESS project also aligns with and supports Connecticut’s ambitious clean energy deployment and climate action targets, including Public Act No. 22-5, mandating zero emissions from electricity supply by 2040, and Public Act No. 21-53, calling for 1000 MW of energy storage to be deployed in Connecticut by 2030.

In conjunction with the announcement of the Tunnel Jet repowering, FirstLight, along with our development partner New Leaf Energy, donated $60,000 in seed funding to Operation Fuel, the only year-round emergency energy assistance program in Connecticut. The funding advanced Operation Fuel’s effort to create a robust training program to build the clean energy workforce of the future that will play a critical role in supporting the clean energy transition in Connecticut and beyond.

Battery Energy Storage Benefits

Battery energy storage systems (BESS) are critical in supporting a reliable decarbonized electric grid thanks to their ability to store energy from intermittent clean resources during times of low demand and dispatch that power during times of high demand. BESS charge using power supplied by the grid during times of low demand and high supply, typically midday when solar is plentiful and at night when the wind is blowing.

Battery energy storage systems can then dispatch that power back onto the grid during times of peak demand, often in the evening when solar generation drops. The availability of storage like BESS allows grid operators to avoid turning to dirty fossil fuel resources to fill generation gaps when working to meet demand. These resources are critical complements to intermittent clean resources like wind and solar and deliver needed reliability as the energy transition advances.

Battery Energy Storage Safety

Safety is paramount in everything we do at FirstLight, including our development of new clean energy and energy storage projects. The Tunnel Battery Energy Storage System will be remotely monitored 24/7, with support from on-site staff at FirstLight’s Tunnel Generating Station. It will adhere to all applicable Connecticut Fire Safety Codes and associated National Fire Protection Association (NFPA) codes and requirements.

FirstLight works exclusively with reputable battery manufacturers whose products meet rigorous requirements listed in National Fire Protection Association (NFPA) 855, Standards for the Installation of Stationary Energy Storage Systems. These requirements include substantial independent testing and certification to UL9540 and UL9540A standards, which are designed to evaluate the fire safety of the batteries and associated systems.

Relevant Links and Documents

Tunnel Battery Energy Storage System Connecticut Siting Council Filing — PE1654

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