Personal Impact

Waste Diversion              Electricity               Solar PV               Transportation

Zero Carbon Energy

Quick Summary - x x dashClimate Change Indicator


The ratio of zero carbon electricity to total electricity generation in Connecticut has been generally declining.

In 2023, electricity generated from both utility scale zero carbon* and carbon-based resources (38,968 thousand megawatt-hours (MWh)) located in the state decreased 7.5 percent from 2022. The amount of zero carbon electricity (14,430 thousand MWh), as a percentage of the total amount of electricity generated in the state, also decreased in 2023 from 2022 levels by approximately 3.8 percent. Approximately 88 percent of the decline in zero carbon generation in 2023 was attributed to nuclear power.84 Including out-of-state generation resources, it is estimated that in 2022 (most recent data available), approximately 60 percent of the electricity supplied to electric customers in the state was from zero carbon resources.85

Zero Carbon Goal - Consumption

Public Act 22-5 requires the reduction of greenhouse gas (GHG) emissions to a level of zero percent from electricity supplied to electric customers in the state by 2040. Since 2011, Connecticut has selected 63 projects totaling over 2,100 MW of Class I resources and 10.9 million MWh of existing nuclear resources.** Of those Class I resources, 484 MW are currently operational with another 479 MW under development. However, since 2011, 20 contracts totaling approximately 1,122 MW of capacity have been terminated.86 On October 27, 2023, DEEP released Requests for Proposals (RFPs) for Offshore Wind Facilities and for Zero Carbon Energy to secure cost-effective zero carbon resources that can improve the reliability of the region’s electric grid and to reduce GHG emissions.87 If the new and previous procurements are developed, it would eventually increase the amount of class I and zero carbon energy available for the state’s residents and businesses; however, it might still leave the state short of its zero percent GHG emission target by 2040. The shortfall is more likely if one or more of the Millstone units are retired and/or the projected increases in electric consumption for transportation (~2,500 gigawatt-hours by 2032)88 and thermal (1,085 GWH by 2032)89 are accurate. The use of intermittent renewable technologies will also require a significant amount of energy storage and/or upgrades to the electric transmission system.

Goal: Connecticut General Statutes Section 16-245a requires that a minimum percentage of electricity, which is sold to Connecticut customers, must be generated from renewable energy sources. That minimum amount is 24 percent for 2022 and will escalate to 40 percent in 2030. 


Technical Note: Personal impact indicators illustrate trends in behavior or practices that can be expected to influence the condition of tomorrow’s air, water, land and wildlife. *Includes utility scale renewables that generate no carbon and nuclear generation, and it is not the same as Class I or Class 2 renewable sources. Zero carbon generation does not include biomass (wood, municipal solid waste), fuel cells operating on natural gas, biogas, and landfill gas. **Includes the environmental attributes associated with the Millstone facilities through 2029.


84 EIA, Electricity Data Browser, Net Generation for Electric Power, Annual (CT - All Fuels); accessed February 29, 2024;,0,1&fuel=vtvv&geo=008&sec=008&linechart=ELEC.GEN.ALL-CT-98.A&columnchart=ELEC.GEN.ALL-CT-98.A&map=ELEC.GEN.ALL-CT-98.A&freq=A&ctype=linechart&ltype=pin&rtype=s&maptype=0&rse=0&pin=.

85 DEEP, Bureau of Energy and Technology Policy; personal communication from M. Malmrose, March 28, 2024.

86 DEEP, Public Act 23-102 – Section 35 Study, Draft Report on Select Connecticut Energy Supply Issues, February 20, 2024;$FILE/PA%2023-102,%20Section%2035%20-%20Study%20Draft%20Report.pdf.

87  DEEP, Grid Scale Competitive Procurements;

88  ISO-New England, Final 2023 Transportation Electrification Forecast, April 28, 2023;

89  ISO-New England, Final 2023 Heating Electrification Forecast, Slide 43, April 28, 2023;