Geothermal Thermal Network

At a glance

• What: Black Swan Labs' wastewater/thermal network (geothermal) proposal.
• Where it stands: monitoring. On 2026-07-21 the Climate Resiliency Committee discussed applying for a $15,000 state wastewater-energy feasibility grant (Black Swan Labs would draft it; DPW would supply sewer data) but took no vote. Council President Ossing and the mayor objected to committing city staff time before the study's scope is clear.
• Earlier (2026-07-07): the committee's first Black Swan Lab presentation. It unanimously voted to explore funding sources for a wastewater-energy feasibility study (no commitment to a study); the Conservation officer and DPW were to be invited to the next meeting.
• Next: a draft grant application to be circulated for comment; committee meeting tentatively 2026-08-03.

First presentation (2026-07-07)

Based on auto-generated captions; names and details may be misheard.

• Audrey Schulman, executive director of Black Swan Lab, presented thermal networks and pointed to three Marlborough sources: a wastewater treatment plant (about 300 homes' worth), the New England Sports Center ice rinks (about 600 homes), and Boston Scientific (bore holes).
• A state DEP wastewater energy recovery grant (about $5 million total, first-come) was described as time-sensitive; the feasibility phase was cited as about $15,000.
• A federal tax credit of 30 to 50% of installation cost was described as direct pay, ending around 2033.
• Open questions: who pays for building retrofits, municipal vs. utility ownership, bore holes on capped landfill or conservation land, and coordination with gas-main replacement.
• Members were cautious about committing city resources before the study is understood. The only vote was a unanimous motion to explore funding sources for the wastewater feasibility study.

The proposal (July 2026)

• Councilor Ducette (committee chair) proposes the city act as broker: landowners build thermal systems (wastewater heat or geothermal wells), the city buys and resells heat to tenants.
• First candidate site: Country Village, an older affordable housing complex on Boston Post Road East, beside a 30-inch sewer main.
• State grant: phase one feasibility up to $15,000 (wastewater only; municipal applicant), phase two design up to $100,000, phase three installation up to $750,000, from about $5 million. Black Swan says each million gallons per day, cooled three degrees, can serve about 100 homes.
• Concerns: no clear funding (TIF may not fit), whether to plan citywide first, staff time, liability, whether the owner should be approached before the study. The mayor wrote a support letter to Black Swan but wants answers first.
• Ducette also floated a non-binding referendum for 2027 and AI-assisted geology mapping; others urged caution on campaign-finance rules and asked that the solicitor be consulted separately.

Background

• Reported to the council through Councilor Ducette's Climate Resiliency Committee minutes.
• Possible state feasibility grants of up to $15,000 were discussed.

Status

• Monitoring, per auto-captions. Since the 2026-07-07 vote only authorized exploring funding, no feasibility study or grant application has been approved.

Discussion time

About 140 minutes across 5 meetings (from transcript timestamps; approximate).

Log

• 2026-08-17 - City Council - Climate Resiliency Committee minutes covered the Black Swan Labs proposal and feasibility grants up to $15,000.
• 2026-07-21 - Climate Resiliency Committee - Black Swan Labs outlined the $15,000 feasibility grant; debate over staff time and scope; Ducette's motion to proceed was withdrawn; draft grant to be circulated; next meeting tentatively August 3.
• 2026-07-20 - City Council - Ducette filed an editorial on geothermal energy and a QR code to the council's geothermal documents; colleagues invited to co-sign.
• 2026-07-07 - Climate Resiliency Committee - Black Swan Lab's first presentation (wastewater, ice rink and Boston Scientific options, grants, tax credit); unanimous motion to explore funding sources for a wastewater-energy feasibility study; next meeting set for July 21.
• 2026-06-22 - City Council - Councilor Ducette filed further geothermal information with a link to be made into a QR code (order 26-1009726).