Connecticut is on hilly terrain between New York’s Hudson River Valley and Rhode Island’s Narragansett Bay. The Connecticut River flows south through the center of the state, and hills give way to coastal lowlands as the river approaches the Long Island Sound. Connecticut is the third smallest state in land area, but it is the fifth most densely populated state in the nation. Its population is concentrated in the southwest, including suburbs of New York City, and along the Connecticut River in the center of the state where the state capital of Hartford is located. Connecticut’s climate varies widely by season and can be influenced by cold, dry air coming down from Canada, warm, humid air coming up from the Gulf of Mexico, or cool, moist air moving in from the North Atlantic. Connecticut does not have any fossil fuel reserves, but it does have wind power potential along its coast and biomass resources in its northern woodlands and from landfills.

Connecticut is one of the lowest energy-consuming states in the nation on a per capita basis. In 2013, the state used the third-lowest amount of energy per dollar of gross domestic product (GDP) in the nation and the fifth-lowest amount of energy per capita overall. The residential sector and the transportation sector lead state end-use energy consumption. The industrial sector consumes the least energy. Insurance, financial services, and real estate are Connecticut’s largest industries, followed by health care and biosciences, large-scale manufacturing, digital media production, and tourism.

Renewable Energy

Quick Facts

  • One of the nation’s two Northeast Home Heating Oil Reserve sites, which are intended to avert disruptions in the supply of home heating oil, is located in Groton, Connecticut.
  • More than one-third of Connecticut households used natural gas for home heating in 2014.
  • Connecticut is second only to Massachusetts in New England in committing demand resources (electricity use that can be turned off during periods of peak demand) to the New England grid.
  • In 2015, 46% of Connecticut’s net electricity generation came from the 2,079-megawatt Millstone nuclear station.
  • Connecticut’s renewable portfolio standard sets a goal of obtaining 23% of the state’s electricity from renewable energy resources by 2020, plus another 4% from conservation and energy from industrial heat. In 2014, 3.5% of Connecticut’s net electricity generation came from renewable energy

Connecticut is encouraging behind-the-meter renewable resources like residential solar PV.

Connecticut gets less than 4% of its net electricity generation from renewable sources. All utility-scale renewable electricity generation was obtained from biomass and hydroelectric sources until late 2013, when a small amount of utility-scale solar photovoltaic (PV) generation came online. By 2016, more than 18 megawatts of utility-scale solar PV capacity had come online in Connecticut. More than 25 additional megawatts is either under construction or in development in the state. Connecticut’s renewable portfolio standard (RPS) calls for 23% of electricity sold in the state to come from renewable energy sources by 2020. Most of that electricity is expected to come from sources such as sustainable biomass, onshore or offshore wind, solar power, and fuel cells. The RPS requires that another 4% must come from commercial and industrial waste heat recovery or conservation. Connecticut electricity providers are meeting their RPS obligations in large part by purchasing renewable energy credits (REC) from other New England states. State planners project that 40% of the state’s 2020 RPS requirement will be met by facilities within Connecticut but that regional renewable resources may not provide enough RECs to meet all New England states’ RPS requirements. In the future, Connecticut may need to import more renewable power from New York and Canada.

Connecticut has initiated a long-term program to encourage small-scale, behind-the-meter renewable energy resources, such as solar PV panels on residences and businesses. In 2015, nearly nine-tenths of the solar PV generation in Connecticut was distributed generation. The state requires retail utilities to offer net metering and time-of-use pricing to encourage the use of renewable sources and efficiency.

Most of Connecticut lacks wind resources suitable for large-scale generation, and the state’s largest wind potential is along its Long Island Sound coastline. The state’s first utility-scale wind project was installed in 2015. Connecticut has only 5 megawatts of installed wind electricity generating capacity in operation, but more projects are under construction. The regional grid operator has been assessing infrastructure upgrades needed to connect wind resources throughout the region.

Connecticut does not have any ethanol plants, but it does have three biodiesel plants. The biodiesel plants use multiple feedstocks and have a combined capacity of more than 24 million gallons per year.


Connecticut’s electricity generation is dominated by nuclear power, from the Millstone Nuclear Power Plant in Waterford, and by natural gas. In 2015, generation from nuclear power and natural gas were almost equal. Although in 2006 natural gas-fired generation provided less than one-third of Connecticut’s total net generation, by 2015, with recent additions of natural gas combined-cycle capability at several generating plants, natural gas contributed almost half of the state’s net generation. In contrast, coal-fired power supplied one-eighth of state generation in 2006, but, by 2015, coal contributed less than 2%. In 2021, the only coal-fired power plant in the state is scheduled to close. Biomass, which provides only slightly more than 2% of state generation, now provides more electricity than either coal or petroleum. Nearly all electricity generation in the state comes from independent producers and municipal utilities.

Connecticut has significant petroleum-fired generating capacity, some of it at dual-fired power plants able to burn petroleum products, mainly diesel fuel and residual fuel oil, and natural gas. And, although one-third of the nameplate generating capacity in Connecticut is petroleum-fired, petroleum contributed less than 2% of the state’s net generation in 2015. The higher-cost petroleum fuels are used in periods of peak power demand. As older generating units age and their costs rise, they are being shut down, raising concerns about how to replace their generating capacity. The regional grid operator, Independent System Operator-New England (ISO-NE), has promoted demand response as one strategy to maintain grid reliability, and Connecticut is a leader in the amount of power reductions its consumers have committed to make during peak demand times and emergencies.

ISO-NE identified a number of problems that threatened electric power reliability in Connecticut and southern New England as a whole. In response, a group of related transmission projects, known as the New England East-West Solution, were undertaken. The final project, the Interstate Reliability Project, was completed in December 2015 with the addition of a high-voltage transmission line and upgraded substations in Connecticut, Massachusetts, and Rhode Island. With the completion of the New England East-West Solution transmission projects, regional transmission bottlenecks are being removed. Connecticut was a net electricity recipient in the past, but total net generation has typically exceeded retail sales in recent years and the state has been a net provider of electricity to other states since 2009.

Connecticut’s per capita electricity use is among the lowest in the nation. Demand for air conditioning is small during the mild summer months, and fewer than one in six Connecticut households use electricity as a primary source for home heating in winter. Connecticut has the highest average retail electricity rates among the Lower 48 states. The state is sponsoring long-term initiatives in energy efficiency and peak demand reduction to help consumers reduce power bills.

Natural Gas

Connecticut does not produce natural gas and receives its natural gas supplies from interstate pipelines. Almost all of the natural gas received in the state arrives through New York. Historically, natural gas has been brought in from producing areas in Canada and from the U.S. Gulf Coast and Mid-Continent regions, but, increasingly, supplies of natural gas are originating from Appalachian Shales, particularly the Marcellus Shale of Pennsylvania. More than one-third of the natural gas entering Connecticut is shipped on to Rhode Island.

Assurance of natural gas supply has become a critical energy issue for Connecticut’s electricity generators.

About one in three Connecticut households uses natural gas as their primary fuel for home heating. Like other New England states, Connecticut does not have any underground natural gas storage facilities and depends on pipeline storage and underground storage capacity in the nearby states of New York, Pennsylvania, West Virginia, and Ohio to meet winter peak demand. As increasing amounts of natural gas are used for electricity generation, in Connecticut and throughout New England, assurance of natural gas supply has become a critical energy issue for the region.

Energy Options

Electric Supply


Electric Utilities

Connecticut Light & Power

United Illuminating


The Connecticut Department of Public Utility Control allows customers of Connecticut Light and Power and United Illuminating to choose alternate electric suppliers. The utilities sold their power plants to open up the industry to competition and now only own the transmission and distribution wires. Customers who do not choose an alternate electric provider receive default supply from the utility.

Public Utilities Commission

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Gas Supply


Gas Supply

Southern Connecticut Gas, Yankee Gas, Connecticut Natural Gas

Natural Gas

Business customers in Connecticut can choose an alternative natural gas provider. Utilities can prevent a customer from switching if the load reduction makes planning system operations difficult. Customers who do not choose an alternate gas supplier receive default sales service from their utility. Under default sales service, customers pay a “commodity charge” which varies as often as monthly.

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