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2018 forecast of capacity, energy, loads, and transmission is published by ISO-NE

Energy usage and peak demand will decline slightly over the next 10 years

On April 30, 2018, ISO New England published the 2018-2027 Forecast Report of Capacity, Energy, Loads, and Transmission (CELT). The report is a primary source for assumptions used in ISO system planning and reliability studies. It provides a snapshot of the New England power system, including:

  • The number of megawatts (MW) with capacity supply obligations resulting from the 12 Forward Capacity Market (FCM) auctions held to date, as well as the total generating capability of resources in the region
  • The breakdown of the region’s generators by fuel type
  • A link to the listing of transmission projects proposed, planned, and under construction
  • The long-term forecast for growth in energy consumption and peak demand, including the contributions of energy efficiency and behind-the-meter solar facilities

The long-term forecast for electricity use is developed each year using state and regional economic forecasts, 40 years of weather history in New England, results of both the ISO’s energy-efficiency (EE) forecast and solar photovoltaic (PV) forecast, and other factors. The ISO calculates a gross forecast and then applies the EE and PV forecasts to develop a net forecast.

The 2018 CELT projects that both energy usage and peak demand will decline slightly in New England over the 10-year period. The primary factors are continuing robust installation of energy-efficiency measures and behind-the-meter solar arrays throughout the region.

CELT projections for 2018 to 2027 

Gross forecast, not including EE and behind-the-meter PV

  • Overall electricity use in New England is expected to grow 0.9% annually over the 10-year period, from the expected 142,488 gigawatt-hours (GWh) this year to 154,364 GWh in 2027
  • Peak demand under normal summer weather conditions of about 90°F (the “50/50” forecast) is expected to rise annually at a rate of 0.8%, from 29,060 megawatts (MW) this year to 31,192 MW in summer 2027 (peak demand is a measure of the highest amount of electricity used in a single hour)
  • Peak demand under extreme summer weather (the “90/10” forecast), such as an extended heat wave of about 94°F, pushes the gross forecast for peak demand up to 31,451 MW in 2018 and 33,828 MW in 2027—an average annual growth rate of 0.8%
  • Winter peak demand under normal weather conditions of about 7°F (the “50/50” forecast) is expected to rise by an average 0.5% annually, from 23,026 MW this year to 24,024 MW in 2027
  • Winter peak demand under extreme weather of about 2°F (the “90/10” forecast) is forecasted to rise by an average 0.5% annually as well, from 23,725 MW this year to 24,723 MW in 2027

Net forecast, including latest EE and behind-the-meter PV forecasts

  • Overall electricity use is expected to decline, by -0.9% annually, from 124,252 GWh this year to 114,980 GWh in 2027
    • EE is projected to save the region an average of 2,059 GWh annually
    • PV is projected to produce about 2,162 GWh of total annual energy savings in 2018, rising to about 4,783 GWh in 2027
  • Peak demand under normal summer weather conditions is expected to fall slightly, by -0.4%  over the 10-year period, from 25,728 MW this year to 24,912 MW in 2027. The net forecast includes peak demand reductions of:
    • 281 MW annually, on average, as a result of EE
    • 633 MW this year and rising to 1,050 MW in summer 2027 as a result of behind-the-meter PV
  • Peak demand under extreme summer weather is expected to remain essentially flat, with a slight -0.2% annual decline , from 28,119 MW in 2018 to 27,548 MW in 2027
  • Winter peak demand is forecasted to decline an average of about -0.7% annually, under both normal and extreme conditions. For normal winter weather, peak demand would slide from 20,357 MW this year to 19,133 MW in 2027; for extreme winter weather, the peak is forecasted to drop from 21,056 MW this year to 19,832 MW in 2027

2017 energy and demand

In 2017, actual energy usage dropped 2.6%, from 124,425 GWh in 2016 to 121,134 GWh last year. If normal weather had occurred in both years, the decline would have been 2.6% as well, from a weather-normalized value of 120,668 GWh to 123,953 GWh.

In 2017, actual demand peaked at 23,968 MW on June 13, 2017, during the hour from 4 to 5 p.m. Without the energy-efficiency measures installed in New England, as well as reductions by demand-response resources, price-responsive demand-side resources, and behind-the-meter solar resources, the peak would have come in at about 27,014 MW. A summer peak in June is unusual; summer peak more typically occurs in July or August, but those months were relatively mild in 2017. Had the heat and humidity of June 13 occurred in July or August, the ISO estimates that actual peak demand would have been about 2,050 higher.

During winter 2017/2018, demand peaked at 20,599 MW during the hour from 5 to 6 p.m. on January 5. Without active demand-response resources and energy-efficiency measures, the peak would have been 23,528 MW. Behind-the-meter solar does not contribute to reducing winter peak load because demand peaks in winter after the sun has set.

Learn more

  • For more information on the 2018 CELT, detailed forecasts and models are available on the Load Forecast webpage
  • Get key statistics on New England’s electricity use and resource mix
  • Track the mix of fuels powering the region in real time via ISO Express