The proposed project will add transmission capacity, support up to 1,200 MW of future onshore wind generation and reduce projected congestion costs across the region.
Eversource and Avangrid’s proposed Transmission Initiative Down East (TIDE) project has been selected by ISO New England as the preferred longer-term transmission solution to address regional power grid needs.
Eversource announced the selection on September 17, 2026, following ISO-NE’s competitive transmission solicitation process.
The proposed TIDE transmission project will strengthen the regional power grid, improve reliability for customers and enable the integration of up to 1,200 megawatts of future onshore wind generation in northern New England.
The project will involve transmission upgrades in New Hampshire, Maine and Massachusetts. With Eversource’s portion primarily focused on infrastructure within existing rights-of-way in New Hampshire.
Construction is anticipated to begin in 2029, pending engineering, environmental, permitting and regulatory approvals.
ISO-NE selects TIDE as preferred transmission solution
TIDE emerged from ISO New England’s competitive transmission solicitation as the preferred longer-term solution to meet regional transmission needs.
The joint proposal from Eversource and Avangrid is designed to expand transmission capacity, ease congestion on the regional power system and support additional energy supplies in northern New England.
Eversource said the project will help improve reliability for customers while supporting the integration of future energy resources.
“This selection is an important step toward delivering the modern, reliable transmission infrastructure New England needs while enabling new supply resources that are so critical to addressing our region’s longstanding energy affordability challenges,” said Bill Quinlan, President of Transmission at Eversource.
The company said the project could help improve affordability by enabling greater supply capacity and easing congestion costs across New Hampshire and New England.
What the TIDE transmission project will include
Eversource’s portion of the TIDE project will primarily involve upgrades and replacement of transmission infrastructure within existing rights-of-way in New Hampshire, with additional work in Maine and Massachusetts.
The New Hampshire portion includes:
- A new 18-mile, 345-kilovolt transmission line.
- Reconstruction of one existing 345 kV line from a two-pole, H-frame design to a single-pole design.
- Reconductoring of another existing 345 kV transmission line.
- Installation of equipment to regulate voltage and power quality.
- Upgrades to existing transmission infrastructure.
The project is designed to maximize the use of established transmission rights-of-way and existing infrastructure.
According to Eversource, this approach is intended to minimize environmental and community impacts while expanding transmission capacity, strengthening the grid and relieving energy bottlenecks.
TIDE to support up to 1,200 MW of future onshore wind
One of the project’s key features is its ability to support additional renewable energy generation in northern New England.
Eversource said TIDE will enable the regional grid to integrate up to 1,200 MW of future onshore wind generation.
The additional transmission capacity is intended to help connect future wind resources in northern New England to the regional grid.
The project’s proposed upgrades would support the movement of electricity across the region while addressing transmission constraints identified through ISO-NE’s planning process.
Eversource did not identify specific wind farms that would use the proposed TIDE transmission project in the announcement.
ISO-NE projects more than $3.4 billion in regional benefits
ISO New England’s analysis projects that TIDE will provide substantial regional benefits, including a benefit-to-cost ratio of more than 2-to-1.
The projected benefits include:
- $1.42 billion in production cost and congestion savings.
- $1.30 billion in avoided capital investment.
- $694 million in avoided transmission investment.
The three figures total approximately $3.41 billion in projected benefits and avoided investment.
These figures are projections from ISO-NE’s analysis. They are not savings already realized by customers.
The analysis indicates that the proposed transmission upgrades could reduce congestion-related costs, avoid some future capital investment and improve the region’s ability to move electricity across its transmission system.
Construction expected to begin in 2029
The selection of TIDE as ISO-NE’s preferred longer-term transmission solution is an important development, but the project has not yet reached the construction stage.
The proposed transmission project still requires extensive engineering, environmental reviews, permitting and regulatory approvals.
Construction is anticipated to begin in 2029, subject to the necessary approvals.
Eversource’s announcement does not specify a final project completion date.
The company said the TIDE project will help deliver the transmission infrastructure needed to support new energy supplies, improve reliability and address regional affordability challenges.
The TIDE project is part of a broader push to expand power infrastructure as electricity demand grows across the United States. In Wisconsin, a major data center grid expansion is also highlighting the need for new energy and transmission infrastructure to support the growing power requirements of AI and data center operations. Together, these developments underscore how investments in electricity infrastructure are becoming increasingly important to meeting rising demand while strengthening grid reliability.
Eversource TIDE transmission project factsheet
- Project name: Transmission Initiative Down East (TIDE).
- Developers: Eversource and Avangrid.
- Selected by: ISO New England.
- Announcement date: September 17, 2026.
- Project states: New Hampshire, Maine and Massachusetts.
- New transmission line: 18 miles at 345 kV.
- Future onshore wind capacity: Up to 1,200 MW.
- Construction start: Anticipated 2029.
- Projected benefit-to-cost ratio: More than 2-to-1.
- Projected production cost and congestion savings: $1.42 billion.
- Projected avoided capital investment: $1.30 billion.
- Projected avoided transmission investment: $694 million.
- Current status: Preferred solution selected; engineering, environmental, permitting and regulatory approvals pending.
- Final project cost: Not stated in the supplied Eversource announcement.
What happens next?
Eversource and Avangrid will need to advance engineering, environmental and regulatory work before construction can begin.
The TIDE transmission project is expected to move forward through the necessary state and regulatory approval processes, with construction targeted for 2029.
If approved and completed as planned, the project will add transmission capacity across northern New England. And support future onshore wind generation and strengthen the regional power grid.
The selection marks another step in the region’s longer-term transmission planning process as ISO New England works to address regional power system needs.
Leave a Reply