Data source: U.S. Energy Information Administration, Hourly Electric Grid Monitor

Electricity generation using fossil fuels increased in New England to meet the additional air-conditioning demand during heat waves in June and July. Natural gas-fired electricity generation made up 56% of New England’s generation mix during the week of the June 16 heat wave, peaking at 61% on June 22. Between July 6 and 13, natural gas-fired electricity averaged 58% of the generation mix. Despite the closure of the Mystic Generating Station in Massachusetts, natural gas accounted for more of the generation mix during both periods compared with the five-year (2019–23) average of 48% for the June 16–23 period and 54% for July 6–13.

On July 10 in New England, 468,403 megawatthours (MWh) of electricity was generated, 31% more than the previous five-year average, and natural gas-fired generation supplied more than half of all the electricity generated in the region. New England has more natural gas-fired generation capacity than it does petroleum- or coal-fired generation capacity; however, use of both also increased during the heat waves to meet the increase in electricity demand.

Natural gas

During the June and July heat waves, more natural gas was consumed in New England’s electric power sector than during the same periods in any of the previous five years. During the week of June 16–23, the electric power sector in New England consumed an average of 1.6 billion cubic feet per day (Bcf/d), according to S&P Global Commodity Insights. Consumption exceeded 2.0 Bcf/d on June 19 and June 20, putting those days among the 15 days with the most natural gas consumed in the electric power sector in New England. Compared with the June heat wave, natural gas consumed for electricity generation the week of July 6–13 remained relatively steady, averaging 1.8 Bcf/d.

Data source: S&P Global Commodity Insights

Petroleum and coal

Use in New England of petroleum and coal to generate electricity also increased during both periods of strong electricity demand. Petroleum- and coal-fired generation make up small percentages of all the generating capacity in New England and are used when electricity demand spikes under extremely hot or cold conditions. On July 11, coal-fired generation made up 2% of the generation supply mix, or 7,038 MWh, compared with an average of 223 MWh in the first half of 2024.

Other sources of generation

Electricity imported from Canada and from New York, as well as use of renewable generation, also increased to meet rising air-conditioning demand in New England during the June and July heat waves. During the week in June, imports from New York and Canada accounted for 9% of the electricity mix; wind, solar, and hydropower generation accounted for 12% of generation; and nuclear accounted for 22%. During the July heat wave, electricity imports averaged 12%; wind, solar, and hydropower accounted for 11% of total generation; and nuclear generation averaged 19% for the week.