Electric Transmission

Electric transmission is the network of high-voltage power lines and associated infrastructure that carries large amounts of electricity from where it is generated to the communities where it is consumed. Think of it as a system of superhighways for electricity: just as interstate highways move goods and people across long distances between cities, transmission lines move electrical energy from power plants, offshore wind farms, and hydroelectric stations to population centers across a region.

In New England, this network connects generation sources—including large power plants in various states, planned offshore wind projects along the coast, and hydroelectric resources in northern New England and eastern Canada—to cities and towns across Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. These high-voltage lines carry electricity at voltages typically ranging from 69,000 volts (69 kV) up to 345,000 volts (345 kV) or higher, enabling the safe and efficient movement of power across long distances.

Without transmission infrastructure, clean energy resources located far from population centers—such as wind farms in northern Maine or hydropower from Canada—could not deliver electricity to homes and businesses in places like Boston, Hartford, or Portland. Transmission is the backbone of the region’s electric system, making it possible to tap into the best energy resources regardless of where they are located.

Transmission and distribution are two distinct stages of delivering electricity from generators to consumers, and understanding the difference is key to understanding grid infrastructure proposals. Transmission refers to the movement of electricity at high voltages over long distances—from power plants to substations closer to areas of demand. Distribution is the final leg, carrying electricity at lower voltages from local substations to individual homes, businesses, and buildings.

In practical terms, transmission lines are the large structures you might see running alongside highways or through rural corridors. Distribution lines are the smaller wires along your neighborhood streets. A new transmission project is fundamentally different in scale, purpose, and regulatory process from distribution-level work. RENEW Northeast focuses exclusively on new transmission projects—the regional infrastructure that enables electricity to flow across the New England grid and will facilitate the growth of clean energy.

🪝Transmission is much like the interstate highway that gets you to major urban areas, while distribution is the local streets that get you to your final destination.

Transmission v. Distribution

Transmission lines stretch across the region, linking places with significant generation potential to the cities and towns where electricity demand is highest. Coastal areas and offshore zones, where wind resources are abundant, need connections to the existing onshore grid. Northern Maine and northern New England, where land-based wind generation and hydropower are located, need stronger pathways to deliver that energy south to population centers in Massachusetts, Connecticut, and Rhode Island.

The existing system also includes interconnections with neighboring power systems—New York to the west and New Brunswick and Québec to the north—which allow the region to import and export power as needed. Upgrades and new connections help balance energy supply and demand across the region so power flows where it is needed most. 

Building a cleaner, more reliable transmission system requires coordinated planning, sustained investment, and meaningful public engagement. New England’s states, utilities, and grid planners are working together through established processes—and newer ones like the Long-Term Transmission Planning (LTTP) framework—to identify where upgrades and new lines will deliver the greatest benefit.

The 2050 Transmission Study provided a roadmap showing that the region will need substantial new transmission capacity to accommodate the growth in renewable energy, the electrification of heating and transportation, and the expected doubling of peak demand by mid-century. The LTTP process now provides the mechanism to translate those study findings into actual projects, with competitive solicitations designed to find cost-effective solutions.

Getting there will take time. Transmission projects involve multi-year planning, environmental review, state permitting, and construction phases. Community engagement and transparency throughout these processes are essential for building public understanding and trust. Over the next several decades, these investments will help the grid support more clean energy, improve reliability during extreme weather, and meet growing demand from electrification.

ISO New England (ISO-NE) is an independent, nonprofit organization that serves as the Regional Transmission Organization (RTO) for the six-state New England region. Established to ensure the reliable operation of the power grid, ISO-NE has three core responsibilities: operating the region’s power system in real time, administering the wholesale electricity markets, and planning for the future of the transmission system.

As the grid’s “traffic controller,” ISO-NE oversees the flow of high-voltage electricity into, within, and out of New England every minute of every day. On the planning side, ISO-NE performs comprehensive analyses to identify where transmission upgrades or new facilities are needed to maintain reliability, improve market efficiency, or support public policy goals set by the states. Because it is independent and does not own generation or transmission assets, ISO-NE evaluates system needs objectively without favoring one resource type over another.

ISO-NE coordinates with the New England States Committee on Electricity (NESCOE), which represents the collective interests of the six states in regional electricity matters. Together, ISO-NE and NESCOE drive the planning processes that shape the future of the regional grid, including Longer-Term Transmission Planning (LTTP) process that looks beyond the traditional ten-year planning horizon.

🪝 If the electric grid is a highway system, ISO New England is like the regional transportation authority. It does not build or own the highways (those are owned by transmission companies like Eversource or National Grid), but it decides where new roads are needed, manages the flow of traffic, and plans for future growth so the system works for everyone.

New England’s transmission system spans thousands of miles across the six-state region, linking generation resources to load centers. Since 2002, more than 870 project components have been placed in service to strengthen the regional grid, and approximately 18 transmission projects were active as of early 2025.

Transmission planning is actively focused on several key areas and needs. The most prominent current effort centers on the corridor between northern Maine and southern New England. ISO-NE’s 2050 Transmission Study identified that transmission bottlenecks along the Maine–New Hampshire and north–south interfaces are high-likelihood concerns that will worsen as more clean energy resources come online in northern New England. 

Other areas of ongoing planning and investment include connections to neighboring regions like New York and eastern Canada, which provide important emergency and economic power flows, as well as offshore wind interconnection planning to accommodate planned wind energy projects along the New England coast. The region is also evaluating reconductoring opportunities in southern Maine, where many existing lines are aging and could carry significantly more power with modern conductor technology.

When regulators evaluate new transmission proposals, they typically consider a broad range of factors to ensure projects serve the public interest. While specific criteria vary by agency and proceeding, common considerations include:

System reliability and need: Does the project address an identified need for maintaining reliable electric service? Regulators assess whether the project resolves congestion, prevents potential overloads, or supports the integration of new generation resources.

Environmental considerations: Proposals are evaluated for their impacts on natural resources, wildlife habitats, wetlands, waterways, and scenic landscapes. Environmental review processes at both the state and federal level assess potential impacts and identify mitigation measures.

Economic benefits and costs: Under the LTTP framework, the ISO evaluates proposals through a cost-benefit analysis, and selected projects must demonstrate that benefits outweigh costs to New England ratepayers. Economic development potential, including construction jobs and local investment, may also be considered.

Property and landowner impacts: Projects must address impacts on private property, including the use of existing rights-of-way where possible. State laws govern the process by which transmission developers can acquire easements, including eminent domain provisions and associated protections for landowners.

Community engagement: Robust engagement with affected communities is increasingly recognized as an essential component of successful transmission projects. The LTTP RFP evaluates applicants on their community engagement plans, and state permitting processes provide multiple opportunities for public input.

Safety and setbacks: Transmission facilities must meet safety standards established by state and federal regulations, including mandatory setback distances from homes and buildings. These requirements help protect public health and safety.

Decommissioning and end of life: Consideration of what happens at the end of a facility’s useful life—including removal, site restoration, and recycling of materials—is becoming an increasingly important factor in project review. Ensuring responsible end-of-life management helps protect communities and the environment over the long term.

Transmission projects involve multiple layers of regulatory review, and there are opportunities for individuals and community members to participate at each level. Understanding the basic landscape of regulatory agencies helps you know where and when to engage.

Federal Level: FERC

The Federal Energy Regulatory Commission (FERC) is the independent federal agency that regulates the interstate transmission of electricity and oversees wholesale electricity markets. FERC does not typically approve the physical construction of transmission lines (that authority generally rests with the states), but it does regulate transmission rates, cost allocation, and the rules governing regional planning processes.

FERC’s Office of Public Participation (OPP) was specifically created to help the public engage in Commission proceedings. OPP provides educational resources, guides for filing comments, and direct assistance with navigating the Commission’s docket system (known as eLibrary). The public can file comments in open dockets, request intervenor status in formal proceedings, and attend public meetings.

When FERC opens a rulemaking proceeding or reviews a tariff filing that affects transmission planning or cost allocation, it publishes notices in the Federal Register and on its website. The public is invited to submit written comments during designated comment periods. These comments become part of the official record and are considered by the Commission.

Regional Level: ISO New England Planning Advisory Committee

ISO-NE conducts its transmission planning process through an open, public forum. The Planning Advisory Committee (PAC) is a stakeholder body that provides input on regional planning processes. PAC meetings are open to all interested parties, and meeting materials—including study scopes, presentations, reports, and responses to stakeholder comments—are posted publicly on the ISO-NE website. Individuals can follow transmission planning developments, review materials, and submit written comments through the PAC process.

State Level: Siting Boards and Public Utility Commissions

In New England, each state has its own agencies responsible for reviewing and approving the construction of transmission facilities within its borders. These agencies go by different names in each state:

When a new transmission project is proposed, the relevant state agency opens a formal proceeding (often called a “docket”). Public participation opportunities typically include:

Public comment periods: Most state agencies accept written comments from the general public during designated periods. Comments are placed into the official record and considered by the decision-makers.

Public hearings: State agencies often hold public hearings in communities affected by proposed projects. These hearings provide an opportunity for individuals to speak directly to regulators and express their views, concerns, or support.

Intervention: Individuals and organizations may petition to become formal “intervenors” in a docket. Intervenors have greater procedural rights than general commenters, including the ability to request information, submit testimony, cross-examine witnesses, and appeal decisions. Requirements vary by state.

Informational sessions: Some state agencies or project developers hold informational open houses or community meetings before or during the formal review process to explain proposals and answer questions.