Spring 2024 update on regional transmission investment now available; 15 projects under construction in New England

An estimated $1.3 billion in power transmission reliability investments are on the horizon through 2027, according to the latest update of ISO New England’s Regional System Plan Project List.

Four upgrades were placed into service in the last few months and three new projects were added, according to the ISO’s March 2024 update.

There are 27 active projects as of this update, including:

  • 15 projects under construction
  • 11 planned projects
  • 1 proposed project

Most of the active projects are in Massachusetts (13) and Maine (8). There are three active projects in New Hampshire, two in Rhode Island, and one in Connecticut. There are no active projects in Vermont.

Since 2002, the ISO’s work in power system planning—one of its three critical roles—has facilitated $12.1 billion in transmission investment, with a total of 868 project components placed into service.

In addition to their primary goal of bolstering reliability, some of the projects have decreased transmission system congestion and prepared the grid for a cleaner future.

About the Project List

Published three times a year (in March, June, and October), the Regional System Plan Project List describes the status of Pool Transmission Facility projects needed to ensure reliability in New England. As a part of the regional system planning process, the ISO must continually:

  • Reassess the timing and components of existing projects to accommodate forecasted changes in net loads, the retirement of generating resources, and the addition or delay of new power resources
  • Study the ability of the New England transmission system to meet federally mandated reliability requirements and adequately serve the region.

A public process

The ISO’s role in system planning includes seeking input from its Planning Advisory Committee. The committee’s open, public meetings provide a forum for stakeholders—including generator owners, transmission owners, government and community representatives, and others—to offer feedback on the regional system planning process.

The committee’s next meeting is April 18 at 9 a.m. via Webex/teleconference.


In addition to helping ensure the region can count on the electricity it needs every minute of every day, transmission system upgrades also help lower wholesale electricity costs and enable the development and use of cleaner energy resources.

Improving the movement of electricity across the region and into areas of limited transmission and high demand:

  • Allows more competition among generators, reduces congestion charges in the energy market, reduces the need for expensive generator reliability agreements, and reduces out-of-market generator dispatch payments.
  • Allows older, more expensive generators to retire, making way for cleaner, more efficient, less expensive resources.
  • Because a reliable system benefits all of New England, eligible costs for transmission upgrades are shared across the region, proportionate to an area’s electricity demand. Transmission owners pay for costs that do not offer a regional reliability benefit. One of the ISO’s responsibilities is to determine, through a collaborative and transparent process, whether project costs will be regionalized or localized.

Tempering factors

Regional energy trends can affect transmission needs. For example, the New England states are national leaders in energy efficiency policies and programs. Energy efficiency savings—when coupled with new generators and other transmission upgrades—may allow the region to defer certain transmission projects deemed necessary to address reliability needs.

With their continued expansion, solar photovoltaic resources and other forms of distributed generation may also one day be able to alleviate or prevent constraints in regional power system transmission or distribution, and reduce or eliminate the need to install new transmission or distribution facilities.

Additionally, market resource alternatives—such as new generators or demand response resources—may in some cases be able to help alleviate transmission needs.

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