Deer Island, the Massachusetts Water Resources Authority's wastewater treatment plant, generated 34,814,562 kWh of its own electricity in FY2025 against a requirement of 144,889,154 kWh. That is a self-generated share of 24.0%, down from 34.1% in FY2017.
More bought, less made
Self-generation at Deer Island fell from 47,756,380 kWh in FY2017 to 37,000,331 kWh in FY2021 and 34,814,562 kWh in FY2025. Purchased electricity rose 19.4% over the same years, from 92,166,934 kWh to 110,046,466 kWh. Renewable output has also slipped against plan: fourth-quarter production was 11,832 MWh in FY2026, 11% below budget, after 12,102 MWh in FY2025, 14% below budget.
Emissions have levelled off
MWRA's total greenhouse gas emissions were 85,636 MTCO2e in 2023, against a 2006 baseline of 144,823. MWRA states that this is 41% below the baseline. Since 2019, however, the total has stayed between 85,247 and 88,375 MTCO2e in the years reported.
The plant that matters
MWRA's main answer is a new combined heat and power plant at Deer Island. Burns & McDonnell holds the US$18.4 million design contract, and the plant is projected to produce 69.3 GWh a year. A battery option of 15.5 MW for four hours carries a US$31 million study estimate. The design contract runs 100 months from October 2024, to about 2032–2033, and MWRA said in May 2026 that the schedule may shift.
Smaller projects first
In September 2026 the board approved a Deer Island solar canopy of up to US$8,899,849, alongside a US$3.8 million wind turbine replacement; about US$10 million of solar at Norumbega is planned for award in FY2027, and a US$20 million state grant was awarded in October 2024.
How these energy projects sit beside the tunnel program, the overflow plan and a budget in which capital financing takes 55.3% of spending is examined in the full report. The full report, Water Utility of the Future: Massachusetts Water Resources Authority, is available for USD 499. For a free overview, read the Massachusetts Water Resources Authority Utility Snapshot.