Editor’s note: This is The Town Minute’s first full Charlton report. Our goal is the same here as it is in Sturbridge: make consequential local proposals easier to understand, with direct links to the original meetings and documents so residents can review the record themselves.
A proposed battery energy storage facility on Carpenter Hill Road drew pointed questions from Charlton residents about fire response, groundwater, noise, tree clearing and who would be accountable if the developer sells the project.
The July 8 meeting was hosted by Carpenter Hill Power and its Florida-based developer, ESA. The company said the project remains in a pre-filing stage and that no permit application has been submitted.
The meeting was intended to gather early community feedback. It also exposed several areas where the project is still preliminary, including the final battery technology, acoustic analysis, stormwater engineering, plume modeling, emergency response plan and the terms of any agreement with Charlton.
This summary is based on the meeting transcript, the developer’s preliminary site plan and information currently published on the project website. The meeting was hosted by the applicant, not a town board, and the developer’s statements should not be read as independent safety findings or final permit conditions.
What is being proposed
Carpenter Hill Power is proposing a battery energy storage facility beside the existing Carpenter Hill electrical substation. The system would be capable of delivering up to 150 megawatts of power and storing 600 megawatt-hours of energy—enough to operate at full output for about four hours.
In practical terms, the batteries would charge when electricity supply is more available and discharge when demand is high. ESA says the facility could supply the equivalent of roughly 120,000 homes for four hours during peak demand.
The preliminary site plan shows:
136 Tesla Megapack 3 units in the current concept
A 15-acre battery project area on a 47.13-acre parcel
A separate project substation and connection to the existing Carpenter Hill substation
A perimeter fire access road, fencing, stormwater features and preserved vegetation intended to serve as a buffer
Equipment at least 50 feet inside the fence
The plan is explicitly marked preliminary and not for construction. ESA also said at the meeting that it is not permanently committed to Tesla equipment and that the layout could change as technology, engineering and the interconnection process advance.
Why this location: ESA said the Carpenter Hill substation connects both 345-kilovolt and 115-kilovolt transmission lines and provides a strategically useful point to move electricity between eastern and western Massachusetts.
More than 5,000 mailers were reportedly sent—but no hands went up
The clearest warning about public outreach came early in the meeting.
An ESA representative asked who had received a postcard in time to learn about the meeting. No one in the room raised a hand.
The company said it had paid a service to send 5,414 mailers. Residents said the room would have been much larger if those notices had arrived on time. ESA called the July event a “dress rehearsal” for additional public meetings and said it would reconsider the timing, venue and outreach channels.
Why it matters: this project is still early enough for residents to influence studies, design details, emergency planning and any community agreement. That opportunity has limited value if people do not know when the discussions are happening.
Residents said the LNG fight still shapes how they see this project
ESA opened the meeting by acknowledging what it called “the elephant in the room”: Charlton’s experience with the liquefied natural gas facility approved through the state siting process despite strong local opposition.
That history immediately shaped the discussion.
One resident said the battery proposal felt like “déjà vu” and worried Charlton would again be heard without having meaningful control over the outcome. Residents living near the site described the area as quiet, wooded and dependent on private wells. Others referenced Charlton’s history of well contamination and said assurances alone would not be enough.
The project has not been approved. ESA said it expects the proposal to go through the Massachusetts Energy Facilities Siting Board’s consolidated permitting process. That means the state will ultimately decide whether the project can move forward, although local boards, residents and town officials can participate and seek conditions.
Fire response and air emissions dominated the discussion
Residents repeatedly asked what would happen if a battery entered thermal runaway—a self-heating failure that can spread within a battery unit and produce fire and gases.
Questions included:
How the system would handle a lightning strike
Whether one failing unit could spread fire to other units
What gases could be released and how far they could travel
Whether firefighters would need a dedicated water source
How contaminated firefighting water would be contained
What equipment, training and mutual-aid support Charlton firefighters would need
ESA representatives said the current concept uses lithium iron phosphate batteries and would be designed around standards including NFPA 855 and UL 9540A testing. They described built-in temperature monitoring, automatic shutdown, ventilation and separation between units as layers intended to prevent a failure from spreading.
They also said the response to a burning battery unit may involve allowing the affected unit to burn itself out instead of applying large amounts of water. Their stated concern was that flooding the unit could create contaminated runoff without necessarily stopping the thermal runaway.
During a live computer demonstration, ESA modeled a battery fire and the possible release of hydrogen fluoride near the unit. Representatives emphasized that a formal, site-specific plume analysis still needs to be completed for different wind and weather conditions.
The demonstration also had limits. When residents repeatedly asked how a lightning strike would affect the system, ESA said it would need to get an answer from the equipment manufacturer and add that scenario to its analysis.
The project website says an emergency response plan is being developed with Charlton Fire Chief Rob Barton. A dedicated public fire-safety webinar is scheduled for August 19.
Wells, runoff and tree clearing remain major concerns
ESA said the project could require clearing approximately 10 acres of mature trees. Representatives acknowledged that removing the canopy and root systems would change how water moves across the property and could increase erosion risk if the site is not carefully managed.
The preliminary discussion identified hydric soils, nearby wetlands, ledge and a 100-year floodplain near the proposed project area. ESA said water generally moves from north to south across the parcel and described a possible swale or catchment area along the southern side of the battery pad.
Those details are not final. Representatives repeatedly said the stormwater system still needs to be engineered.
Residents with private wells asked not only about ordinary stormwater, but also what would happen if smoke, battery materials or firefighting water reached the soil or groundwater during an emergency.
ESA said normal operations would not use water or burn fuel. That does not resolve the larger emergency-response question, which will depend on the final site design, plume analysis, containment measures and response plan.
ESA expects to sell the project before construction
One of the most consequential disclosures involved ownership.
ESA said its business is to develop the project, secure the necessary rights and permits, and then sell it to a separate owner-operator with the capital to build and operate the facility.
The company currently has a lease option rather than ownership of the land. Representatives said the full operational lease would take effect only if the project receives approval and moves forward.
ESA estimated an operating life of roughly 35 to 50 years, with battery components replaced during that period.
Residents asked the obvious follow-up: who is accountable if ESA leaves, a future owner fails, or the project reaches the end of its life?
ESA said permit conditions would remain attached to the project and bind a future owner. The developer’s current website also says financial assurance will be required for decommissioning and restoration. The amount, form and responsible parties were not established during the July 8 discussion.
A benefit plan is not the same as a binding agreement
ESA is beginning a Community Benefits Plan process to identify what Charlton should receive if the project is built. Possible topics include fire equipment and training, road improvements, environmental work, local hiring and tax revenue or a payment-in-lieu-of-taxes agreement.
No benefit package or tax figure has been finalized.
The meeting also clarified an important distinction: a Community Benefits Plan is not automatically legally binding. A signed Community Benefits Agreement would be.
An ESA representative said the company was cautious about entering a binding agreement before selling the project because it could increase development risk. The same representative also acknowledged that Charlton might not accept a nonbinding plan by itself and said the company may need to work through an agreement with the town.
That will be one of the most important issues to follow. A list of intended benefits is different from an enforceable agreement that identifies dollar amounts, deadlines, responsible parties and remedies if commitments are not met.
Can public feedback actually change the design?
Near the end of the meeting, a resident asked whether ESA was willing to change the technology, footprint, spacing, elevation and site design—or whether it was mainly trying to manage objections.
ESA said the company is open to changing the equipment and site specifications, provided the revised design still meets the technical requirements of the batteries and grid interconnection.
That answer now creates a measurable standard for the months ahead: what did residents ask for, what changed as a result, and what did not?
What happens next
The project remains in pre-filing community engagement. Residents may want to watch for:
Fire Safety Webinar: Wednesday, August 19, with virtual sessions from noon to 1 p.m. and 7 to 8 p.m.
A completed acoustic study and projected sound levels at the property line
A site-specific plume analysis and emergency response plan
Final stormwater, wetland and environmental studies
Clarification of lightning protection and firefighting-water strategy
The proposed tax or PILOT structure
Whether community benefits become part of a binding agreement
Any revisions to the battery technology, site footprint, screening or setbacks
Formal notice when the project files with the state
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The Town Minute is an independent publication not affiliated with the Town of Charlton, Carpenter Hill Power, ESA or any municipal office. While we strive for accuracy, errors or omissions may occur. For official and complete records, consult the applicable government filings, project documents and original meeting recording.
