Millstone operation is critical factor for zero-carbon goals

12 October 2021

The continued operation of Dominion's Millstone nuclear power plant beyond 2029 is a critical factor in how much more and how quickly Connecticut needs to procure new clean energy additions, the state's Department of Energy and Environmental Protection (DEEP) has told policymakers in the state's newly released 2020 Integrated Resources Plan (IRP).

Millstone (Image: Dominion)

The latest IRP, a statutorily required recurring assessment of Connecticut's future electric supply needs and potential means to meet those needs, is also the state's first assessment of pathways to achieve a 100% zero-carbon electricity supply by 2040, as directed by Governor Ned Lamont in a 2019 Executive Order. There are  "multiple achievable pathways " to meet that target, it says in its Key Findings.

The two-unit 2088 MWe Millstone pressurised water reactor plant generates about 47% of Connecticut's electricity - and 90% of its carbon-free electricity - but had been at risk of retirement until the signature in 2019 of a long-term contract with state utilities for 9 million MWh of energy - until 2029. Preventing the retirement of the plant "saved the region from significant negative impacts on the region's electric grid with respect to fuel diversity, energy security, and grid reliability; avoided an estimated USD1.8 billion … in replacement costs that would have been borne by Connecticut ratepayers, and prevented regional carbon emissions from increasing by 20%," the IRP notes.

DEEP's IRP tests five scenarios against two different forecasts of electricity consumption trends: a Base case, in which electricity consumption continues on the existing trajectory based on current energy policies, and an Electrification case, in which the deployment of electric vehicles and building heating technology are assumed to triple by 2040. Four of the scenarios assume that Millstone will continue to be at risk at the end of its current contract and will retire when that contract ends in 2029, while one assumes that the state's contract with Millstone is extended.

The IRP scenarios in which the nuclear plant continues to operate in the period to 2040 - the so-called Millstone Extension scenarios - show continued operation of the plant would: reduce the total cost of meeting the 100% zero carbon target by offsetting the need for new incremental resources; allow the state of Connecticut to meet emissions reductions targets in all of the modelled years; and allow greater fossil fuel retirements across the region than other scenarios. Continued operation of Millstone would see 8.3 GW of regional fossil fuel retirements by 2040 under the Base case, and 8.7 GW regional fossil fuel retirements by 2040 under the Electrification case.

"Establishing a regional mechanism for valuing the reliability and zero carbon aspects of Millstone's electricity generation is one alternative to provide for the continued operation of this resource beyond 2029," the plan says.

If Millstone were to continue to operate beyond 2029, it should be supported regionally through a reformed wholesale market, or by "some other regional mechanism", the report notes. Although the modelling of the Millstone Extension scenarios assumes the current contract is extended, "this IRP does not recommend that Connecticut's electric ratepayers should take on that burden on behalf of the region again."

"Current energy markets are not producing significant investment in clean energy resources, causing Connecticut to have to procure, through state jurisdictional markets and mechanisms, the resources needed to meet the State's Renewable Portfolio Standard and other GHG emission reduction goals," the plan notes. "The wholesale market's overreliance on natural gas generation has placed Connecticut ratepayers at risk of paying unreasonable and duplicative costs for clean energy supply, and taking on additional costs to preserve fuel security in the region." It calls for Connecticut and the other states in the New England region to "drive" reform in the regional wholesale markets "to ensure they are meeting the needs of the states and their ratepayers, including Connecticut's need to meet emissions reduction goals and provide reliability at the lowest cost to ratepayers."

Researched and written by World Nuclear News