New England’s Offshore Wind Solution

On Most Days in Winter 2024–2025, Cold Weather Strained the New England Power Grid, Increasing the Risk of a Blackout

Long cold spells during the 2024–2025 winter drove up electricity demand, which remained higher than average as consumers used electricity for heating, including running furnaces, water heaters, and space heaters more frequently and for longer periods (ISO-NE 2025a). Total daily energy demand—a key reliability risk factor tracked by grid operator ISO New England (ISO-NE)—rose above 350,000 megawatt-hours (MWh) on 53 of the 90 days between December 1, 2024, and February 28, 2025 (59 percent of all days) (Figure 1) (ISO-NE n.d.a). This increased the region's risk of an energy shortfall, a condition that can lead to a blackout (ISO-NE 2022).¹ On four of those days, daily energy demand exceeded 400,000 MWh, ISO-NE's next critical threshold, further increasing the chance of a shortfall.

Offshore Wind Energy Was Abundant and Would Have Significantly Lowered the Risk of a Blackout

Wind speed data for this period indicates that offshore wind projects would have delivered large amounts of energy throughout the winter season (Hersbach et al. n.d.). ² This would have offset the increased demand on the system and substantially reduced the risk of an energy shortfall, thereby lowering the chance of a blackout.

Energy Delivered by a 1,500 MW Offshore Wind Fleet

Had the Vineyard Wind (800 MW) and Revolution Wind (700 MW) offshore wind projects been fully operational in winter 2024–2025, the two projects would have provided enough energy to reduce the net load on the system below the 350,000 MWh threshold on 29 of the 53 days that otherwise would have been at risk of an energy shortfall. This small offshore wind fleet (1,500 MW) would have kept the grid entirely out of the "elevated risk" (yellow) zone during much of the season, eliminating 55 percent of the underlying demand-driven risk (light blue line in Figure 1).

Energy Delivered by a 3,500 MW Offshore Wind Fleet

With the addition of two 1,000 MW projects, the total energy supply from the 3,500 MW offshore wind fleet would have eliminated demand-driven risk on all but 13 days of winter 2024–2025. ³ This would have reduced the original number of days with risk (53) by 75 percent (dark blue line, Figure 1). On three of the remaining days with risk, the offshore wind fleet would have moved the system down from the "higher risk" (orange) zone to the "elevated risk" (yellow) zone by reducing the net load below 400,000 MWh.

Energy from Local New England Resources Can Reduce the Need to Import Liquified Natural Gas in Winter

New England has long depended on supplemental energy supplies to meet its needs in winter. On the coldest days, when the supply of pipeline gas has not met demand for both heating and electricity, the region has filled the gap by importing liquified natural gas (LNG) from other parts of the world (ISO-NE n.d.b). In winter 2024–2025, 22 million dekatherms (Dth) of imported LNG—enough fuel to support an estimated average hourly output of 1,300 MW from gas-fired generation—were injected into the regional interstate pipeline system to augment the total available gas supply (Figure 2) (ISO-NE IMM 2025). While these injections helped to meet the surge in demand, reliance on imported LNG exposes consumers to the volatility of global commodity prices. Moreover, it can result in extreme cost increases when global markets are tight (Robinson 2022).

Sustained commitment by New England states to developing renewable energy has begun to provide an alternative pathway for meeting their winter energy needs. Already, the local solar and onshore wind fleet contribute substantially to the winter energy supply. During winter 2024–2025, solar resources, including rooftop installations, delivered an hourly average of 590 MW over the course of the season; onshore wind supplied an hourly average of 540 MW (Figure 2) (ISO-NE 2025b, ISO-NE 2025c, ISO-NE 2025d, ISO-NE 2026a, ISO-NE 2026b).

Based on wind speed data for this period, an offshore wind fleet would have made an even larger contribution. A 1,500 MW fleet would have delivered an hourly average of 690 MW; a 3,500 MW fleet would have delivered an hourly average of 1,610 MW. Including this additional supply from offshore wind would have brought the total supply from local renewable resources to an hourly average of 2,740 MW, more than double the supply from imported LNG. With an offshore wind fleet delivering energy at this scale, local renewable resources can support a regional shift away from dependence on LNG imports.

Such a shift would benefit consumers significantly. As more renewable energy enters the wholesale energy market, it will displace increasing amounts of high-marginal-cost energy, resulting in market-wide reductions in the wholesale price of electricity (Appunn 2015). A recent analysis of the impact of a 3,500 MW offshore wind fleet found that average energy market prices would have been 11 percent lower during this period, saving consumers $400 million (Daymark 2025).

With continued support from New England leaders, the development of an offshore wind fleet promises to bring these reliability and affordability benefits home to consumers in the coming years.