New Hampshire Power Grid: Blackout Risk, Reliability & Outlook

New Hampshire's ISO New England grid relies critically on the Seabrook nuclear station—New England's largest generator—while aging infrastructure, natural gas supply constraints, and limited in-state generation alternatives create persistent reliability and energy cost concerns.

Last updated: 2026-02-02 · Data: EIA, NERC, state utility commission filings

Meta description: New Hampshire power grid analysis: Seabrook nuclear dependence, natural gas reliance, ISO New England challenges, and infrastructure investment outlook for 2026.

The Grid Reality in New Hampshire

New Hampshire operates within ISO New England's six-state regional grid, serving 1.4 million residents with 3,400 megawatts of installed capacity. The state's power mix centers on the 1,244-megawatt Seabrook Nuclear Station, which generates roughly 60% of in-state electricity production, making New Hampshire one of America's most nuclear-dependent states.

Natural gas fills most of the remaining baseload, with smaller contributions from hydroelectric and biomass facilities. Despite this generation capacity, New Hampshire imports approximately 30% of its electricity from neighboring states through ISO New England's regional market. This import dependence reflects both economic dispatch dynamics and the aging of several smaller fossil plants that have retired in recent years.

The state's electricity demand peaks around 1,600 megawatts during summer cooling periods, well below total installed capacity. However, winter heating electrification and data center expansion are driving steady demand growth of 1.2% annually — modest but persistent pressure on an increasingly constrained regional grid.

Key Vulnerabilities

• Single-point nuclear failure: Seabrook provides 60% of state generation. Any extended outage would force massive imports through already-strained transmission lines

• Natural gas pipeline constraints: Kinder Morgan's Tennessee Gas Pipeline serves most NH gas plants, but winter heating demand creates fuel competition and price volatility

• Transmission bottlenecks: Limited high-voltage connections between northern and southern NH create internal congestion during peak demand

• Extreme weather exposure: Ice storms regularly down distribution lines, while heat waves stress aging transformers across the ISO-NE region

• Retirement cascade risk: Regional coal and oil plants continue shutting down, leaving New England increasingly dependent on natural gas and imports during peak periods

The Demand Surge

New Hampshire faces modest but accelerating electricity demand growth driven by three key factors. Data center development is expanding, particularly around Manchester and Nashua, as companies seek reliable power and fiber connectivity between Boston and Montreal corridors.

Electric vehicle adoption is accelerating among the state's higher-income residents, with EV registrations growing 45% in 2025. Meanwhile, heat pump installations are increasing as residents seek alternatives to heating oil and propane, supported by state rebate programs and federal tax credits.

Population growth remains limited at 0.3% annually, but the demographic shift toward remote workers and retirees is increasing residential electricity consumption during traditional off-peak hours, flattening the daily demand curve.

Infrastructure Spending Pipeline

New Hampshire's grid modernization centers on transmission upgrades and distribution resilience. The $84 million Granite Bridge pipeline project will enhance natural gas supply reliability for Merrimack Station and other facilities, reducing winter fuel constraints.

Eversource is investing $150 million in transmission line upgrades between 2024-2027, including the rebuild of the 115kV Scobie Pond-Portsmouth line. These projects address both reliability and capacity constraints as regional electricity trade increases.

Federal infrastructure funding is flowing through multiple channels: $12 million from the Infrastructure Investment and Jobs Act for grid hardening, plus additional Inflation Reduction Act allocations for clean energy transmission. The Northern Pass transmission line concept remains dormant after 2018 regulatory rejection, but smaller interconnection projects continue advancing through ISO New England's planning process.

What This Means for Investors

New Hampshire's nuclear-heavy generation mix and transmission constraints create specific investment opportunities in the broader New England grid buildout. The state's dependence on Seabrook makes nuclear services and fuel cycle companies particularly relevant, while natural gas infrastructure investments benefit from the region's backup power requirements.

Transmission equipment manufacturers like General Electric and ABB have direct exposure to ongoing grid upgrades across ISO New England. Eversource (ES) operates New Hampshire's largest utility franchise and continues investing heavily in grid modernization. For broader regional exposure, the Invesco Solar ETF (TAN) includes significant holdings in companies building renewable projects across New England.

The state's modest size limits direct infrastructure investment opportunities, but New Hampshire serves as a bellwether for broader New England grid dynamics. Regional capacity shortfalls and transmission constraints are driving the $14 trillion national grid rebuild, with New England leading both the crisis and the solution.

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Frequently Asked Questions

Is New Hampshire's power grid reliable?

New Hampshire's grid reliability depends heavily on the Seabrook Nuclear Power Plant, which at 1,250 MW is the largest generating station in New England. When Seabrook is at full capacity, New Hampshire is a net power exporter. Any extended Seabrook outage, however, would create a significant regional supply shortfall. Winter gas constraints across New England also affect New Hampshire's reliability, as gas-fired generators may face fuel curtailment during extreme cold. The state's forested terrain makes the distribution system vulnerable to storm damage.

What causes blackouts in New Hampshire?

Nor'easters and ice storms are the primary blackout drivers, with New Hampshire's heavily forested landscape amplifying tree-related outages during wind events. The 2008 ice storm left over 400,000 customers without power, many for more than a week. High winds during any season can cause widespread distribution outages. Winter cold snaps can create regional generation shortfalls when gas supply is constrained across New England.

How is New Hampshire investing in grid infrastructure?

Eversource is investing in distribution system upgrades and vegetation management to reduce storm vulnerability. Transmission projects are improving New Hampshire's connection to regional ISO New England resources. Solar development is growing, primarily through net-metered distributed generation. The state's energy policy focuses on maintaining competitive energy markets and supporting Seabrook's continued operation as a cornerstone of regional reliability.

What is New Hampshire's energy mix?

New Hampshire generates approximately 55% of its electricity from nuclear (Seabrook), with natural gas providing about 15% and biomass contributing a notable share. Hydropower from small dams across the state adds flexible generation. Wind and solar are growing but remain small contributors. The dominance of Seabrook makes New Hampshire's generation among the cleanest in the region, but it also creates concentration risk around a single facility.

This analysis is part of Energy Macro's state-by-state grid infrastructure research. For our complete framework on positioning for the $14 trillion grid rebuild — including specific allocations and income strategies — see The Blackout Fortune Playbook.

Updated: February 1, 2026 | Data sources: EIA, ISO New England, New Hampshire Public Utilities Commission