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Maine (US-ME)

Market Type: Deregulated (Retail Choice)
SSS Relevance: ⭐⭐⭐ High
Grid Carbon Intensity: See emissions section

SSS Factors: significant nuclear capacity, hydroelectric resources

1. Overview​

Maine operates a deregulated electricity market where supply (generation) and delivery (transmission and distribution) are separated. Consumers can purchase electricity from Competitive Electricity Providers (CEPs) or remain on the Standard Offer service, while utilities such as Central Maine Power (CMP) and Versant Power manage the regulated delivery infrastructure 1.

The state's electricity generation profile is relatively low-carbon compared to the U.S. average. In 2024, renewable resources accounted for 57% of in-state net electricity generation, ranking Maine 9th in the nation for renewable share. The primary sources include hydropower (32%), wind (27% of renewable electricity), biomass (10%), and solar (13% of total in-state generation) 2. Consequently, Maine ranks 44th in the U.S. for total carbon dioxide emissions from the electric power sector 2. The estimated grid carbon intensity for 2025 is 228 gCO2eq/kWh (or 221 g/kWh based on 2024 EIA data) 2.

Maine is part of the regional ISO New England (ISO-NE) grid, though Northern Maine is managed by the Northern Maine Independent System Administrator (NMISA) and connects to New Brunswick, Canada 1. Despite high in-state renewables, over 50% of the broader New England grid relies on natural gas, which acts as the primary marginal fuel source 1. This reliance, combined with grid modernization efforts to improve reliability against extreme weather, contributes to higher costs. As of March 2026, the average residential electricity rate is approximately 29.55 ¢/kWh, which is the second lowest in New England but remains 27–51% higher than the national average 1.

The state has enacted aggressive Clean Energy Standards to further decarbonize the grid. Current mandates require 80% of electricity retail sales to come from renewable sources by 2030. Following legislation in 2023 and 2025, the goal was accelerated to achieve 100% clean energy by 2040 (defined as 90% renewable sources and 10% clean resources like nuclear or large-scale hydro) 1.

2. Market Structure​

Maine operates a restructured electricity market that separates power generation from delivery. Most consumers can choose their electricity supplier through retail choice, while utilities maintain the transmission and distribution infrastructure 1. The market is served primarily by two large investor-owned utilities (IOUs)—Central Maine Power (CMP) and Versant Power—which together serve approximately 97% of the state's electricity customers 3. CMP, a subsidiary of Avangrid, serves over 560,000 customers, while Versant Power serves approximately 135,000 customers 4. The remaining customers are served by consumer-owned utilities, including cooperatives and municipal utilities 5.

Wholesale Market and Grid Operations The wholesale electricity market and grid operations for most of the state are managed by ISO New England (ISO-NE), which acts as the Regional Transmission Organization (RTO) and Independent System Operator (ISO) 6. ISO-NE is responsible for grid reliability, administering wholesale markets for energy and capacity, and conducting long-term system planning 7. The Northern Maine Independent System Administrator (NMISA) manages the grid in Aroostook and Washington counties, an area not synchronously connected to ISO-NE but linked to the Eastern Interconnection via New Brunswick, Canada 7.

Retail Choice and Standard Offer Consumers in Maine can purchase electricity from Competitive Electricity Providers (CEPs) or remain on the Standard Offer. The Standard Offer is a default service rate established through a competitive bidding process overseen by the Maine Public Utilities Commission (PUC) 1. While retail choice allows for potential savings and access to renewable energy plans exceeding the state's Renewable Portfolio Standard (RPS)—which targets 80% by 2030—reports indicate that some residential customers who switched to CEPs overpaid compared to the Standard Offer in recent years 1. ⚠️ Note: The search results cite reports from "early 2026" regarding customer overpayments, suggesting a future context or a discrepancy in the provided timeline.

Recent Developments In November 2023, Maine voters rejected a referendum (Question 3) to replace the state's investor-owned utilities with a nonprofit, consumer-owned utility called Pine Tree Power 8. Concurrently, voters approved Question 1, requiring voter approval for any utility seeking to incur over $1 billion in debt, a measure that complicates future public takeover attempts 8. In late 2025, the Maine PUC established new Standard Offer prices resulting in rate increases for 2026, while also unanimously rejecting a proposed five-year rate hike from CMP in November 2025 9.

3. Clean Energy Policy​

Maine has significantly accelerated its clean energy requirements, mandating 100% clean electricity by 2040. This goal, codified in June 2025 through LD 1868, advances the previous target date by a decade 10. The mandate utilizes a dual-track strategy comprising the Renewable Portfolio Standard (RPS) and a new Clean Energy Standard (CES) 11.

Targets and Standards

  • 2040 Goal: The state requires 90% of electricity to come from renewable sources (e.g., wind, solar) and 10% from "clean resources" (e.g., nuclear, large-scale hydro) 12.
  • Intermediate Goal: An interim target requires 80% renewable energy by 2030 1.
  • Climate Goals: Beyond electricity, Maine aims for statewide carbon neutrality by 2045 and a 45% reduction in greenhouse gas emissions below 1990 levels by 2030 13.

Resource Classifications The standard categorizes eligible resources into distinct classes for compliance purposes:

  • Class I & IA: New renewable facilities operating after September 1, 2005 (wind, solar, small hydro) 14.
  • Class II: Existing resources operating before 2005 (biomass, hydro), typically serving a 30% baseline 14.
  • Class III: A new category for the CES including nuclear and hydro with specific fish passage requirements. Requirements for Class III begin at 1% in 2031, increasing 1% annually to 10% in 2040 15.
  • Thermal RECs (TRECs): A separate requirement targets 4% thermal energy from renewables for heating/cooling by 2030 14.

Implementation and Oversight

  • Administration: The Maine Public Utilities Commission (PUC) oversees certification and compliance. Concurrent legislation (LD 1270) elevated the Governor's Energy Office to a cabinet-level Department of Energy Resources to lead procurement efforts 16.
  • Compliance: Suppliers must obtain Renewable Energy Credits (RECs) or pay Alternative Compliance Payments (approximately $50/MWh for Class I/IA) into the Renewable Resource Fund 1.
  • Exemptions: Supply contracts active as of September 30, 2025, are exempt from new Class III requirements until their terms expire 15.

Impact and Status

  • Economic: A state assessment indicates the RPS has saved ratepayers an average of $21 million annually since 2011. Reaching the 100% goal by 2040 is projected to save households approximately $1,300 per year by reducing reliance on imported fossil fuels 17.
  • Progress: As of 2024, approximately 54% of in-state electricity generation comes from renewable sources, though the state remains dependent on imported natural gas and heating oil 13.
  • Jobs: The state targets 30,000 clean energy jobs by 2030, reporting roughly 20,300 workers as of 2025 18.

4. Utility Landscape​

Maine's electricity delivery market is primarily served by two investor-owned utilities (IOUs) which handle transmission and distribution for approximately 95-96% of the state's population and electricity load 119. These utilities are regulated by the Maine Public Utilities Commission (MPUC) 1.

Investor-Owned Utilities (IOUs)

  • Central Maine Power (CMP): The largest utility in the state, serving over 646,000 customers in southern and central Maine. CMP is a subsidiary of Avangrid, which is majority-owned by the Spanish energy giant Iberdrola 191.
  • Versant Power: The second-largest utility, serving roughly 154,000 customers in eastern and northern Maine. It was formed from the merger of Bangor Hydro Electric and Maine Public Service and is owned by ENMAX, a company based in Calgary, Canada 191.

In November 2023, Maine voters rejected a ballot initiative (Question 3) that sought to replace these two IOUs with a statewide consumer-owned utility called Pine Tree Power 1.

Consumer-Owned Utilities (COUs)

Maine also has nine consumer-owned utilities (COUs), consisting of rural electric cooperatives and municipally-owned utilities 2021. Unlike the for-profit IOUs, COUs are non-profit entities owned by customers or local governments, often offering lower rates 5.

  • Electric Cooperatives: Owned by the members they serve, typically in rural areas.
    • Eastern Maine Electric Cooperative (EMEC): Serves Aroostook, Penobscot, and Washington counties 21.
    • Fox Islands Electric Cooperative: Serves Vinalhaven and North Haven 1.
    • Isle au Haut Electric Company, Matinicus Plantation Electric Company, and Monhegan Plantation Power District 1.
  • Municipal Utilities: Owned and operated by local governments.
    • Houlton Water Company, Kennebunk Light & Power District, Madison Electric Works, and Van Buren Light & Power District 1.

Generation Ownership

The delivery utilities generally do not own the power plants. The largest generation owner in Maine is Brookfield Renewable, which operates dozens of dams and generates approximately 87% of the state's hydropower 2022.

5. SSS-Eligible Resources​

ResourceTypeCapacity (MW)SSS EligibleNotes
average age of active hydroelectricHydro130✅ Yes (pre-RPS)Legacy hydro
The average age of activeHydro130✅ Yes (pre-RPS)Legacy hydro

6. EAC/REC Registry Infrastructure​

Maine does not maintain a state-exclusive registry for tracking Energy Attribute Certificates (EACs), commonly referred to as Renewable Energy Certificates (RECs). Instead, the state relies on two distinct regional systems depending on the service territory:

  • NEPOOL Generation Information System (GIS): This is the primary tracking system for the majority of the state. It serves as the native compliance registry for the New England Power Pool, issuing and tracking RECs for every megawatt-hour (MWh) of electricity generated within the ISO New England region 23. It is used to track Class I, Class IA, and Class II resources.
  • North American Renewables Registry (NAR): This system specifically serves the Northern Maine Independent System Administrator (NMISA) region. Participants in this territory must register accounts and facilities through NAR to track RECs from meter data reporting through to retirement for Maine RPS compliance 24.

Certification and Eligibility To be eligible for RECs, generation facilities must be certified by the Maine Public Utilities Commission (PUC). This applies to Class I, IA, and Thermal RECs (TRECs) 1. While Class I, IA, and Thermal resources require PUC certification to ensure state eligibility criteria are met, Class II resources typically utilize self-certification directly within the NEPOOL GIS system 1.

System Functionality These registries prevent "double counting" by assigning a unique serial number to each MWh of renewable generation. Certificates carry data such as fuel type, emissions rates, facility location, and vintage, and must be retired (canceled) once a renewable energy claim is made to verify compliance with the state's goal of 100% clean energy by 2040 25.

7. Grid Emissions​

Generation Mix​

Scope 2 Reporting​

  • SB 253 requires Scope 2 reporting for companies >$1B revenue

Source: EPA eGRID, EIA, state regulatory filings

References​

Sources & Last Updated​

Research Date: 2026-03-10
Data Sources: EIA, EPA eGRID, state regulatory filings, SerpAPI research aggregation

This page was generated using automated research and may contain inaccuracies. Verify critical data with primary sources.

Footnotes​

  1. Maine.gov ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14 ↩15 ↩16 ↩17 ↩18 ↩19 ↩20

  2. U.S. Energy Information Administration (EIA) (.gov) ↩ ↩2 ↩3

  3. Legal Planet ↩

  4. The Portland Press Herald ↩

  5. The Conversation ↩ ↩2

  6. Federal Energy Regulatory Commission (.gov) ↩

  7. ISO New England ↩ ↩2

  8. Utility Dive ↩ ↩2

  9. Maine Morning Star ↩

  10. Maine Monitor +3, Maine Beacon ↩

  11. Freedom Energy Logistics ↩

  12. Maine.gov +1, Maine Beacon ↩

  13. The Equation - Union of Concerned Scientists ↩ ↩2

  14. Database of State Incentives for Renewables & Efficiency ↩ ↩2 ↩3

  15. Foley Hoag ↩ ↩2

  16. Maine.gov +5, Maine Public ↩

  17. Maine.gov +5, The Equation - Union of Concerned Scientists ↩

  18. Maine Public ↩

  19. Third Way ↩ ↩2 ↩3

  20. The Maine Monitor ↩ ↩2

  21. Eastern Maine Electric Cooperative ↩ ↩2

  22. Bangor Daily News ↩

  23. Maine.gov, Flexidao ↩

  24. Maine.gov, Xpansiv ↩

  25. U.S. Environmental Protection Agency, Maine.gov ↩