ISO-NE has published the request for proposals for its first longer-term transmission planning (LTTP) procurement, which is focused on increasing North-to-South transmission capacity in New England and interconnecting onshore wind resources in Northern Maine.

The March 31 RFP is the culmination of months of work between ISO-NE, the New England states and stakeholders from across the region, and it could set the precedent for future procurements to meet anticipated transmission needs. (See FERC Approves New Pathway for New England Transmission Projects.)

The main objectives and requirements of the RFP were established by the New England States Committee on Electricity (NESCOE) in December. (See ISO-NE to Work on State-backed RFP for Northern Maine Transmission.)

NESCOE defined the objectives as “strengthening the connection between northern and southern New England,” and “facilitating the integration and deliverability of additional affordable generation resources located in Maine.”

At a minimum, proposed projects must increase the transfer limit of the Maine-New Hampshire interface to 3,000 MW, the limit of the Surowiec-South interface to 3,200 MW and establish new infrastructure in Central Maine to facilitate the interconnection of 1,200 MW of onshore wind. The RTO wrote that applicants could propose upgrades that go beyond the minimum requirements.

The Maine-New Hampshire interface currently has a transfer limit of 2,000 MW, and the Surowiec-South interface has a limit of 1,800 MW.

“All three of these needs must be addressed by Dec. 31, 2035, unless a QTPS [qualified transmission project sponsor] respondent can demonstrate supply chain issues that warrant a later in-service date,” ISO-NE wrote in the RFP.

The two interfaces were identified as high-likelihood concerns in ISO-NE’s 2050 Transmission Study. The focus on onshore wind is driven by its significant potential for low-cost renewable energy production in Northern Maine. (See Long Road Still Ahead for Aroostook Transmission Project.)

The deadline for project submissions is Sept. 30. ISO-NE expects to take about a year to evaluate proposals and select a preferred solution.

Applicants will be required to submit a $100,000 deposit, which will be used to cover study costs. Project sponsors can submit solo or joint proposals, but all proposals must be complete solutions. ISO-NE plans to publish a summary of every proposal received for the RFP.

The RTO wrote that project developers can include in their proposals “corollary upgrades” to infrastructure in the service territory of a different participating transmission owner (PTO).

“As part of the corollary upgrade, the PTO may install new facilities only to interconnect the QTPS respondent’s longer-term proposal to the PTO’s existing transmission system. Any other corollary upgrades must only be upgrades or replacements of existing facilities,” ISO-NE wrote.

The RTO noted that corollary upgrades could include “reconductoring an existing line, rebuilding an existing line, rebuilding a single existing circuit in a double-circuit configuration … multiple-circuit tower separation, operating voltage changes or replacement of circuit breakers with higher-rated breakers.”

Other than infrastructure to interconnect the project, applicants cannot propose new infrastructure in another TO’s service territory without an agreement or joint proposal with the TO.

To screen proposals, ISO-NE will perform steady-state, stability and short-circuit analyses, as well as a transfer analysis “to confirm that the required minimum interface capabilities on the Maine-New Hampshire and Surowiec-South interfaces in the future year are met.”

The RTO also will conduct energy and capacity tests to assess whether the solution will facilitate the required onshore wind interconnection.

If a project passes all the screening tests and meets all the requirements, ISO-NE will conduct a cost-benefit analysis, calculated based on “an independent capital cost estimate, using a consistent capital cost estimating methodology, to ensure consistency in its review of the longer-term proposals and their cost estimates.”

To be eligible for selection, the cost-benefit analysis must show that the project would provide the region with net cost benefits. If no projects pass this threshold, one or more states could opt to cover the costs that exceed the benefits.

The analysis will include capacity expansion, production cost and resource adequacy models to calculate benefits, which it will evaluate over a 20-year period after a project’s in-service date.

ISO-NE also will calculate the benefits of avoided transmission investments “based on the extent to which the project eliminates the need for projects already included on the [Regional System Plan] project list, replaces assets that are already planned to be replaced due to asset condition and included on the Asset Condition List, or replaces assets that are likely to be replaced due to equipment age.”

For all projects that pass the cost-benefit threshold, ISO-NE will “holistically” consider both quantitative and qualitative factors to select the preferred solution. The highest-priority factors in this evaluation will include life-cycle costs, cost-containment provisions, permitting challenges, potential to interconnect additional resources and incorporate future needs, and impacts on system performance.

Lower-priority factors will include operational, environmental and winter reliability impacts, project constructability, and the use of advanced transmission technologies.

ISO-NE will present its preliminary preferred solution to the Planning Advisory Committee for feedback. After ISO-NE posts the preferred solution, NESCOE will have the opportunity to terminate the process or submit an alternative cost allocation methodology.

In a press release, Advanced Energy United wrote that the RFP “demonstrates that with the right planning and collaboration, we have the will and means to build the transmission infrastructure necessary to power a clean energy future,” adding that “it is critical to ensure that this RFP results in well vetted, competitively sourced projects getting built quickly to bring net benefits to New England.”