New England has more than enough electricity on hand even if extreme weather hits this winter, according to an estimate from the organization that runs the six-state power grid.

The announcement, while not a surprise, is important because this is the first winter since Pilgrim Nuclear Power Station shut down last May. The closure of large power plants like Pilgrim has led to some concern about electricity supplies during extreme cold spells, when natural gas that would otherwise be fueling electric plants is needed for heating. 

“The Pilgrim retirement coincided with several new resources coming online, including three dual-fuel plants capable of using either natural gas or oil to produce power, as well as solar and wind resources,” noted ISO-New England in its announcement.

ISO-NE noted that peak grid demand – the greatest amount of electricity needed at any one moment during the winter – “has remained relatively flat in New England in recent years as a result of increased use of energy-efficiency measures and behind-the-meter solar photovoltaic systems.”

Those solar systems, such as panels placed on a home’s roof, reduce the amount of electricity that the grid must provide. ISO-NE noted that this has limits, however.

“While (solar photovoltaic) helps reduce energy consumption during sunny winter days, electricity demand peaks in winter after the sun has set,” the report said. Even so, daytime solar can help nighttime power production indirectly: “By reducing demand on sunny days, PV can help preserve other fuels for use when demand is peaking.”

Overall, ISO-NE predicted that peak demand this winter will be 20,476 megawatts, or as much as 21,173 megawatts during extreme winter weather, defined as 5 degrees below long-term normals. A megawatt is a million watts and for comparison, Seabrook Station generates about 1,200 megawatts at full blast.

Both those figures are well below the 32,747 megawatts available from power plants. Importantly, they are also well below the roughly 28,000 megawatts that would be available even after discounting “natural-gas-fired generating capacity at risk of not being able to get fuel when needed.”

Last year’s winter peak was 20,773 megawatts. The all-time winter peak as 22,818 megawatts during a 2004 cold spell, but New England now uses more electricity in summer than winter. The all-time peak usage was 28,130 megawatts on Aug. 2, 2006.

ISO-NE is an independent, not-for-profit corporation responsible for the operation of New England’s power grid. It predicts electricity supply in advance of each winter and each summer.