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Long-term forecasts: Electricity usage will remain flat and peak demand is expected to grow slowly

ISO-NE has published its annual CELT, energy efficiency, and PV forecasts

ISO New England has published its 2016-2025 Forecast Report of Capacity, Energy, Loads, and Transmission (CELT), a primary source for assumptions used in ISO system planning and reliability studies. It provides a 10-year snapshot of the New England power system, including the total generating capacity of resources in the region, the breakdown of the region’s generators by fuel type, a link to the list of transmission projects proposed, planned, and under construction to ensure system reliability, and the long-term forecast for growth in energy use and peak demand. ISO New England’s long-term forecast for electricity use is developed each year using state and regional economic forecasts, 40 years of weather history in New England, and other factors. The CELT also includes results from the ISO’s latest energy-efficiency (EE) forecast and solar photovoltaic (PV) forecast, which project the load-reducing effects of EE resources and “behind-the-meter” PV resources connected at customer sites to local distribution systems.

CELT projections for 2016 to 2025

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

  • Overall electricity use in New England is expected to grow 1.0% annually over the 10-year period, from 140,269 gigawatt-hours (GWh) in 2016 to 152,731 GWh in 2025
  • Peak demand under normal weather conditions of about 90°F (the “50/50” forecast) is expected to rise annually at a rate of 1.0%, from 28,966 MW in 2016 to 31,794 MW in 2025 (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 31,303 MW in 2016 and 34,452 MW in 2025—an average annual growth rate of 1.1%

Forecast including latest EE and behind-the-meter PV forecasts

  • Overall electricity use falls to a -0.2% annual growth rate, from 128,014 GWh in 2016 to 125,213 GWh in 2025
  • Peak demand under normal weather conditions is expected to slow to a 0.2% annual growth rate, from 26,704 MW in 2016 to 27,122 MW in 2025
  • Peak demand under extreme summer weather is expected to slow to 0.3% annually, from 29,042 MW in 2016 to 29,781 MW in 2025



Summer peak demand in this graph is based on the “90/10” forecast, which accounts for the possibility of extreme summer weather, such as an extended heat wave of about 94°F.

Examples of EE measures include the adoption of energy-efficient lighting, appliances, cooling, and building operations. EE measures are projected to save the region 9,648 GWh of energy, in total, from 2020 to 2025, with an average annual savings of 1,608 GWh.

The majority of New England’s PV resources are connected behind the meter at customer sites on local distribution systems and are not dispatchable by the ISO. These resources are forecast to produce 1,301 GWh of energy in 2016 and 2,959 GWh in 2025, lowering the demand for electricity from the regional power grid.

Source: Data from Final ISO New England Energy-Efficiency Forecast 2020–2025 and Final 2016 Solar PV Forecast Details (May 2016)

2015 energy and demand

Looking back at 2015, actual electric energy usage declined by 0.2%, to 126,899 GWh, compared to 2014 demand. In 2015, actual demand peaked at 24,437 MW on July 20, 2015. 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 26,472 MW.

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