Resource Mix

Over the past 20 years, New England’s wholesale electricity markets have attracted billions of dollars in private investment in some of the most efficient, lowest-emitting power resources in the country—providing reliable electricity every second of every day, lowering wholesale prices, shifting costly investment risk away from consumers, and reducing carbon emissions. Because private firms make this investment and not public utilities, consumers are shielded from the investment risks they had been exposed to before the introduction of competitive markets.

Sources of Electricity Used in 2018

Here’s the breakdown of the amount of electricity produced by generators in New England and imported from other regions to satisfy all residential, commercial, and industrial customer demand during 2018. This is called Net Energy for Load (NEL).

Note: Data is preliminary, pending a 90-day resettlement period. (Last update: 1/18/19.) For the most current information, download the Net Energy and Peak Load by Source spreadsheet in ISO Express.

Fast Stats
  • 350 dispatchable generators
  • About 31,000 MW of generating capability for summer and 33,000 MW for winter (seasonal claimed capability)
  • About 47% of the region’s electric generating capacity uses natural gas as its primary fuel (roughly 15,000 MW), with 11% more listing it as a secondary fuel
  • About 21,100 MW of new generating capacity, mostly wind, proposed to be built, though many projects ultimately withdraw (source: October 2019, ISO Interconnection Queue)
  • Roughly 7,000 MW of generation have retired since 2013 or will retire in the next few years, with another 5,000 MW from coal- and oil-fired plants at risk of retirement in the coming years
  • Over 3,100 MW of active demand response (DR) and energy efficiency and other passive demand resources are registered in New England (February 2019 DRWG monthly statistics)
  • About 1,500 MW in summer and 1,000 MW in winter of imported electricity are obligated to be available for the region—most from Canadian hydropower
  • Over 150,000 solar power installations totaling about 2,900 MW (nameplate), with most connected “behind the meter”
GWH (a) % of GENERATION % of NEL

(a) GWh stands for gigawatt-hour.

(b) As of January 2016, this chart approximates the amount of generation by individual fuels used by dual-fuel units, such as natural-gas-fired generators that can switch to run on oil and vice versa. Previously, the report attributed generation from such units only to the primary fuel type registered for the unit. The new reporting flows from changes related to the Energy Market Offer Flexibility Project implemented December 2014. See the notes in the Net Energy and Peak Load by Source Report for more details.

(c) “Other” represents resources using a fuel type that does not fall into any of the existing categories. Other may include new technologies or new fuel types that come onto the system but are not yet of sufficient quantity to have their own category.

(d) Tie lines are transmission lines that connect two balancing authority areas. A positive value indicates a net import; a negative value represents a net export.

(e) The energy used to operate pumped storage plants.

(f) Generation
+ net interchange
- pumping load.

Total Generation (b) 103,702 100.0% 84%
Gas 50,511 49.0% 41%
Nuclear 31,385 30% 25.5%
Renewables 10,788 10.4% 8.7%
Wind 3,367 3.2% 2.7%
Refuse 3,018 2.9% 2.4%
Wood 2,698 2.6% 2.2%
Solar 1,212 1.2% 1%
Landfill Gas 448 0.4% 0.4%
Methane 45 0.04% 0.04%
Steam 0 0.0% 0.0%
Hydro 8,708 8.4% 7.1%
Oil 1,161 1.1% 0.9%
Coal 1,109 1% 0.9%
Price-Responsive Demand 25 0.02% 0.02%
Other (c) 15 0.01% 0.01%
Net Flow over External Ties (d) 21,409   17%
Québec 13,877    
New Brunswick 4,044    
New York 3,487    
Pumping Load (e) -1,804   -1.4%
Net Energy for Load (f) 123,307   100.00%

Lower-Emitting Resources Supply Most of the Region’s Electricity

In 2018, natural-gas-fired generation, nuclear, other low- or no-emission sources, and imported electricity (mostly hydropower) provided roughly 99% of the region’s electricity.

With low-cost fuel from domestic shale deposits, advances in technology, and smaller generators that are easier to site, natural gas-fueled power plants have proliferated in New England over the past two decades. Market participants have invested billions into new, efficient (meaning they use less fuel), relatively low-emitting natural-gas-fired generation. Nearly half of the region’s electric generating capacity uses natural gas as its primary fuel (about 15,000 MW), and natural-gas-fired power plants produce about 40% of the grid electricity consumed in a year.

Markets Respond to Changing Times: Resources on the Way OUT

Aging coal-fired, oil-fired, and nuclear power plants are closing largely because their fuel and environmental-mitigation costs make them too expensive to effectively compete against natural-gas-fired generators and growing levels of renewable-energy resources that have no fuel costs, low operational costs, and incentives designed to lower their initial capital investments. Since 2013, roughly 7,000 MW of generation have retired or announced plans for retirement in the coming years. This includes predominantly oil, coal, and nuclear power plants. Another 5,000 MW of remaining coal- and oil-fired generation are at risk of retirement. The region’s remaining two nuclear facilities (Millstone and Seabrook, which produce a combined 3,300 MW) will be critical components of the hybrid grid because they are carbon free and have a dependable, on-site fuel supply. Nuclear power currently supplies a quarter of the grid electricity consumed in the region per year. Source: ISO New England, Status of Non-Price Retirement Requests and Retirement De-list Bids; March 14, 2019.

Generators closed or retiring in New England

Notable exits include:

  • Brayton Point Station (1,535 MW from oil and coal)
  • Salem Harbor Station (749 MW from oil and coal)
  • Vermont Yankee (604 MW from nuclear power)
  • Pilgrim Nuclear Station (677 MW from nuclear power)
  • Norwalk Harbor Station (342 MW from oil)
  • Mount Tom Station (143 MW from coal)
  • Bridgeport Harbor Station (564 MW from coal)

Nuclear, oil, and coal generators are critical on the coldest winter days when natural gas supply is constrained (as shown below). Coal- and oil-fired resources also make valuable contributions on the hottest days of summer when demand is very high or major resources are unavailable. However, as more and more resources with on-site fuel that can sustain operation for extended periods (oil, coal, nuclear, dual-fuel generation) retire and are displaced by resources with limited-energy “inventories” (natural gas generation, wind, solar, battery storage) the grid at times may not be able to supply enough energy to meet electricity demand.

Oil generation is high during extreme winter cold

Tomorrow’s Energy Mix: Resources on the Way IN

All six New England states have renewable energy standards, which require electricity suppliers to provide customers with increasing percentages of renewable energy to meet state requirements.

State Renewable Portfolio Standards

The New England states are also promoting greenhouse gas (GHG) reductions on a state-by-state basis and at the regional level, through a combination of legislative mandates and aspirational goals.

State Goals Seek Reductions

To meet these requirements, some New England states began offering additional incentives to bring more solar, hydro, and wind power on line over the past few years. More recently, several New England states have established public policies that direct electric power companies to enter into long-term contracts for carbon-free energy that would cover most, if not all, of the resource’s costs. Massachusetts for example directed its utilities to sign 20-year contracts committing the state’s electricity customers to pay for the development of large-scale offshore wind and hydroelectricity import projects. In addition, the federal Bureau of Ocean Energy Management recently auctioned leases in offshore Massachusetts for additional wind development. This public policy trend is expected to grow as legislators seek to accelerate the transition to a clean-energy economy.

States Accelerate Procurement of Renewable Energy

State(s) State Procurement Initiatives for Large-Scale Clean Energy Resources Resources Eligible/Procured Target MW (nameplate)
Clean Energy RFP
390 MW
MA 2017
Section 83D
Clean Energy RFP
Hydro Import Approx. 1,200 MW
(9,554,000 MWh)
Section 83C Offshore Wind RFP
Offshore Wind 1,600 MW (MA)
400 MW
CT 2018
Energy RFP
Offshore Wind,
Fuel Cells,
Anaerobic Digestion
254 MW
CT 2018
Zero-Carbon Resources RFP
Nuclear, Hydro,
Class I Renewables
Energy Storage
Approx. 1,400 MW
(12,000,000 MWh)
RI 2018 Renewable Energy RFP Solar, Wind,
Small Hydro,
Fuel Cells and other Renewables
400 MW

Note: Nameplate MW may be higher than qualified Forward Capacity Market capacity MW.

Developers of renewable resources are taking note, and this interest is reflected in the ISO interconnection queue for new generation. As of October 2019, about 21,100 MW have been proposed in the ISO Generator Interconnection Queue.

by type, by state

Wind power dominates new resource proposals. In 2018, the amount of new wind power seeking interconnection in New England was for the first time more than double the amount of natural gas-fired generation proposed—and today, there are four times more wind power proposals than natural gas. Of the roughly 13,700 MW (nameplate) of wind power being proposed regionally (as of October 2019), over 12,000 MW would be offshore of Massachusetts, Rhode Island, and Connecticut, with most of the remaining located onshore in Maine. Additional investment in transmission infrastructure will be fundamental to reliably move large amounts of clean energy from remote locations. Learn more about transmission needed to support a hybrid grid.

Most solar power in New England is connected to local distribution utilities or “behind the meter” directly at retail customer sites. Because such projects do not follow the ISO interconnection process, they aren’t reflected in the ISO Queue numbers above. The ISO must still track solar power’s growth in the region for forecasting and planning purposes, however, since it reduces demand on the grid; the region had over 150,000 solar power installations at the end of 2018. Read more about solar power in New England—its growth, locations, and effects on the system, as well as how the ISO is handling related challenges.

illustration of battery

Energy storage is “charging” ahead. For more than 40 years, New England has enjoyed the benefits of two large-scale pumped-hydro energy- storage facilities that can supply almost 2,000 MW of capacity within 10 minutes. Now, new storage technologies are emerging, driven by technological advances, falling costs, and support from the states. Today, the region has about 20 MW of grid-scale battery storage capacity; currently proposed new projects could add more than 2,300 MW of battery storage capacity over the next few years.

Current battery technologies run for short periods and may not help during tight system conditions that may occur over longer periods like days or weeks. If these resources need to be charged during a system contingency, they would not be able to provide help but would instead sit idle or drain energy needed for grid reliability. Until electric storage or other technologies have the ability to supply quick energy for longer periods and in greater quantities, flexible natural-gas resources are a necessary element of the hybrid grid, not only to help supply the “missing energy” when the weather is uncooperative for wind and solar resources, but also to provide the precise grid-stability and reliability services that renewables generally cannot.

Battery Projects in New England

In addition, 2,600 megawatts (MW) of energy efficiency (EE) measures can reduce electricity demand from New England’s power grid. New England states continue to invest billions of dollars on EE programs ($5.3 billion invested from 2012 to 2017; projected $10.6 billion will be spent between 2020 and 2028) that promote the use of energy-efficient appliances and lighting, and advanced cooling and heating technologies. Massachusetts, Rhode Island, Connecticut and Vermont rank among the top five states in energy efficiency in the U.S., according to the American Council for an Energy-Efficient Economy's 2018 rankings.

Unlike EE and behind-the-meter PV, which are passive demand resources, active demand resources (also known as demand-response resources) can be dispatched by the ISO. Demand-response resources can reduce their electricity consumption from the regional grid “on demand,” by powering down machines (load management), by switching to an on-site generator (distributed generation), or by switching to a storage device (batteries). Demand-response resources provided about 400 MW of the region’s total capacity needs in 2018. And, after a multi-year development effort, on June 1, 2018, ISO New England became the first US grid operator to deploy demand-response resources as part of the energy dispatch and reserve-designation process along with generating resources. Integrating demand-response resources directly into the wholesale market for energy and reserves was a long-sought after but complex goal. During the first three months, active demand response accounted for 10.4 GWh of reduced system demand.

New England Energy Efficiency and Power Resources with Significant Growth

Read about solar power in New England—its growth, locations, and effects on the system, as well as how the ISO is handling related challenges.

Learn about how ISO New England is actively pursuing innovations to help create a more efficient, responsive, reliable system that can handle expanded renewable generation and smart grid technology.

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