What is Electricity Transmission?
Electricity grids are comprised of two components:
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A transmission system, which moves large amounts of electricity from power plants over high-voltage lines to major substations; and
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A distribution system, which provides local, lower-voltage power from major substations to smaller residential and commercial consumers.
Many transmission lines cross state and national borders, allowing for regional grid interconnection. Most of Maine shares a regional electric grid with New England, which is made possible by a network of transmission lines connecting each of the states. The New England regional grid also facilitates the movement of electricity between Canada and the United States.
In recent years, many states including Maine have recognized the need for enhanced grid planning to meet clean energy goals in an efficient manner. Transmission and distribution utilities conduct grid planning to forecast how much electric demand there will be, whether their current assets and equipment are sufficient to meet that need, and, if not, what investments will be required.
Transmission planning has historically been conducted by transmission companies. The transmission system is regulated by the Federal Energy Regulatory Commission, and proposed transmission projects in New England are reviewed by ISO-New England which operates the grid on a daily basis. Distribution system planning is generally conducted by local utilities and regulated by state agencies such as the Maine Public Utilities Commission (PUC). In 2022, the Maine state legislature passed a law requiring utilities to undertake a new grid planning process that includes stakeholder input to identify priority areas for utilities to address in their plans. These grid plans must be filed with the PUC every five years.
As Maine works to increase affordability and bring more renewable energy resources online to meet statutory requirements and goals, the State is prioritizing regional planning and coordination to ensure that clean power can be delivered in a reliable, efficient, and cost-effective manner to households and businesses. Improving interregional electricity transmission planning and coordination can also stabilize energy costs by increasing access to affordable clean energy while bolstering grid reliability at times of high energy demand and improving resilience against extreme weather. To that end, the Maine Governor's Energy Office (GEO) works in partnership with various state agencies, federal and local officials, industry, nonprofits, and research institutions to conduct regional transmission system planning.
Transmission Planning Initiatives
Northeast States Collaborative on Interregional Transmission
In 2023, a group of Northeast states led a request to the U.S. Department of Energy (DOE) to convene and support a multi-state initiative, the Northeast States Collaborative on Interregional Transmission, in a first-in-the-nation effort to explore mutually beneficial opportunities to increase the flow of electricity between three different planning regions in the Northeast and assess offshore wind infrastructure needs and solutions.
In July 2024, GEO announced that Maine has joined a total of 10 Northeast states in signing a memorandum of understanding (MOU) for improved regional planning of electricity transmission to create a stronger, more reliable, and more efficient grid and accelerate the clean energy transition. Other states joining the MOU include Connecticut, Delaware, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island, and Vermont. Through this MOU, the Collaborative sets forth its agreement to work together on interregional transmission infrastructure and establishes mechanisms for sharing information. More information about the Collaborative and the MOU is available here.
Federal-State Modern Grid Deployment Initiative
In May 2024, Maine joined 20 other states and the Biden-Harris Administration to form the Federal-State Modern Grid Deployment Initiative. The initiative aims to bring together states, federal agencies, and power sector stakeholders to help drive grid adaptation quickly and cost-effectively to meet the challenges and opportunities that the power sector faces in the twenty-first century. The states have committed to prioritize efforts that support the adoption of modern solutions to expand grid capacity and build modern grid capabilities on both new and existing transmission and distribution lines.
Regional & National Transmission Studies
North-South Interface Transfer Capacity Pilot Project
The ISO-New England 2050 Study identified the congested south-central Maine transmission system as a major source of concern in meeting regional clean energy goals. This area of congestion, known as the North-South Interface, will need to be upgraded significantly to unlock onshore and offshore wind energy to meet projected system requirements in the coming years. GEO has coordinated with the U.S. DOE’s Grid Deployment Office and will be working together to identify cost-effective ways to maximize transfer capacity of existing grid resources.
U.S. Department of Energy Studies
The U.S. DOE has requested that states support several major transmission studies, including the Atlantic Offshore Wind Transmission Study, West Coast Offshore Wind Study, and the National Transmission Planning Study. Maine GEO staff are supporting this work via DOE’s Technical Review Committee and Advisory Committee to assist in the preparation, review, and editing of these studies, and have engaged in numerous technical meetings and webinars.
Questions?
If you have questions about GEO’s work on transmission, please email geo@maine.gov.