April 29, 2025

Monthly wholesale electricity prices and demand in New England, March 2025

Wholesale power prices averaged $45.48 per megawatt-hour (MWh) in the Real-Time Energy Market in March 2025, up 96% compared to the previous year.¹ Day-Ahead Energy Market averages were $46.97/MWh, up 94% from March 2024.

By the numbers

March 2025 and Percent Change from March 2024 and February 2025	March 2025	March 2024	February 2025
Average Real-Time Electricity Price ($/megawatt-hour)	$45.48	96.5%	−64.0%
Average Natural Gas Price ($/MMBtu)	$4.26	161.3%	−70.9%
Peak Demand	17,344 MWs	10.5%	−7.5%
Total Electricity Use	9,295 GWh	0.4%	−6.6%
Weather-Normalized Use²	9,709 GWh	-0.8%	−2.3%

Drivers of wholesale electricity prices

In general, the two main drivers of wholesale electricity prices in New England are the cost of fuel used to produce electricity and consumer demand.

Power plant fuel

Fuel is typically one of the major input costs in producing electricity. Natural gas is the predominant fuel in New England, used to generate 55% of the power produced in 2024 by New England’s power plants, and natural-gas-fired power plants usually set the price of wholesale electricity in the region. As a result, average wholesale electricity prices are closely linked to natural gas prices.

The average natural gas price during March was $4.26 per million British thermal units (MMBtu).³ The price was up 161% from the March 2024 average Massachusetts natural gas index price of $1.63/MMBtu. The Mass. index price is a volume-weighted average of trades at four natural gas delivery points in Massachusetts, including two Algonquin points, the Tennessee Gas Pipeline, and the Dracut Interconnect.

Wholesale electricity and natural gas prices

Electricity demand

Demand is driven primarily by weather, as well as economic factors. Energy usage during March increased 0.4% to 9,295 GWh from the 9,257 GWh used in March 2024. The average temperature during March was 41˚ Fahrenheit (F) in New England, down 1˚ from the previous March. The average dewpoint, a measure of humidity, was 27˚F in March, down 3˚ from the previous March. There were no cooling degree days (CDD) during March, which is normal for New England.⁴ In March 2024, there were no CDD. There were 754 heating degree days (HDD) during March, while the normal number of HDD in March is 882 in New England. In March 2024, there were 728 HDD.

Consumer demand for electricity for the month peaked on March 3 during the hour from 6 to 7 p.m., when the temperature in New England was 29°F and the dewpoint was 4°. Demand reached 17,344 MW. The March 2025 peak was 10.5% higher than the March 2024 peak of 15,694 MW, set during the hour from 7 to 8 p.m. on March 21, when the temperature was 33°F and the dewpoint was 7°.

Peak demand is driven by weather, which drives the use of heating and air conditioning equipment. The all-time high winter peak was 22,818 MW, recorded during a cold snap in January 2004 when the temperature was −1°F and the dewpoint was −20°. The all-time peak demand in New England was 28,130 MW, recorded during an August 2006 heat wave, when the temperature was 94°F and the dewpoint was 74°. Air conditioning use is far more widespread than electric heating in New England, so weather tends to have a relatively greater impact on the summer peak than the winter peak.

Monthly peak demand and total and weather-normalized energy use

Resource mix and emissions

The mix of resources used in any given time period depends on price and availability, as well as supplemental resource commitments needed to ensure system stability. Natural-gas-fired and nuclear generation produced about 76% of the 8,875 GWh of electric energy generated within New England during March, at about 48% and 28%, respectively. Renewable resources generated about 14.5% of the energy produced within New England, including 4.6% from wood, refuse, and landfill gas; 4.6% from wind; and 4.6% from solar resources. Hydroelectric resources generated 9.8%. Coal and oil resources did not generate a significant amount of energy. The region also received net imports of about 572 GWh of electricity from neighboring regions.

The mix of resources used to produce the region’s electricity is a key driver of carbon dioxide (CO₂) emissions. The ISO estimates these emissions through an analysis that blends data on electricity generation by fuel type with an emissions factor for each fuel that is based on data from the Environmental Protection Agency.⁵

March estimated CO₂ emissions in New England, by fuel source (metric tons)

New England power plants produced an estimated 2.22 million metric tons of CO₂ in March 2025, a 2.7% decrease from the previous March.

Estimated CO₂ emissions from natural-gas-fired plants—typically the region’s largest source of power system emissions, due to the significant amount of electricity these resources produce—decreased year over year, falling from 1.75 million metric tons to 1.66 million metric tons. These resources accounted for 75% of the power system’s estimated emissions.

Together, oil- and coal-fired resources produced an estimated 6,387 metric tons of CO₂ in March 2025 (0.3% of the total), down from an estimated 9,334 metric tons in March 2024. Because the region’s wholesale electricity markets select the lowest-priced resources needed to meet demand, oil- and coal-fired resources tend to run more frequently when natural gas prices rise, and less frequently when natural gas prices are low.

CO₂ emissions from other resources—mostly refuse and wood—were estimated at 552,591 metric tons, a 6% increase from March 2024. These resources accounted for about 25% of the power system’s estimated CO₂ emissions for the month.

Estimated year-to-date emissions through March 31 increased 4.4% year over year, which was largely driven by a colder winter, resulting in higher demand and more oil- and coal-fired generation. Regional CO₂ average annual emissions from electric generation have declined significantly in the last decade. The ISO New England Electric Generator Air Emissions Reports provide a more comprehensive analysis of New England electric power generator air emissions and a review of relevant system conditions.

March year-to-date estimated CO₂ emissions in New England, by fuel source (metric tons)

1. One megawatt (MW) of electricity can serve about 750 to 1,000 average homes in New England. A megawatt-hour (MWh) of electricity can serve about 1,000 homes for one hour. One gigawatt-hour (GWh) can serve about 1 million homes for one hour.

2. Weather-normalized demand indicates how much electricity would have been consumed if the weather had been the same as the average weather over the last 20 years.

3. A British thermal unit (Btu) is used to describe the heat value of fuels, providing a uniform standard for comparing different fuels. One million British thermal units are shown as MMBtu.

4. A degree day is a measure of heating or cooling. A zero degree day occurs when no heating or cooling is required; as temperatures drop, more heating days are recorded; when temperatures rise, more cooling days are recorded. The base point for measuring degree days is 65 degrees. Each degree of a day’s mean temperature that is above 65 degrees is counted as one cooling degree day, while each degree of a day’s mean temperature that is below 65 degrees is counted as one heating degree day. A day’s mean temperature of 90 degrees equals 25 cooling degree days, while a day’s mean temperature of 45 degrees equals 20 heating degree days.

5. The factors used to calculate estimated CO₂ emissions were updated in September 2024. ISO New England analysts regularly review and refine the methodology used to develop these emissions factors, in order to reflect the characteristics of New England’s generating fleet and improve the accuracy of the estimates.

6. Observations drawn from year-over-year comparisons provided in this month’s report should consider that February 2024 had 29 days, while February 2025 had 28.