The Federal Energy Regulatory Commission has denied a request by the developer of the proposed Burrillville, R.I., power plant to preserve a key power-purchase contract.

That contract, known as a capacity supply obligation (CSO), was withdrawn by ISO New England, operator of the regional power grid, because of delays in the approval process. In its cancellation letter to Invenergy Thermal Development, ISO New England said the Chicago-based developer repeatedly missed construction benchmarks. ISO New England no longer wanted Invenergy to profit from selling its CSO to a third party.

On Sept. 20, the Federal Energy Regulatory Commission (FERC) opened the power-purchase cancellation case. Invenergy lobbied to keep it in place, arguing that the proposed Clear River Energy Center would improve the regional power grid and alleviate natural-gas demand.

In FERC filings, Invenergy blamed the delays on “a small number of very vocal, well-funded opponents intent, from day one, on simply causing the clock to run out on Clear River by requiring it to swat back seemingly any conceivable argument that, while possibly creative, almost invariably was shown to be legally infirm.”

FERC recognized that ISO New England had the authority to cancel the CSO if the project overran its planned start by two years. Despite an unusually long three-year permit vetting in Rhode Island, Invenergy is sticking with its competition date of 2021.

The CSO auction was created to help power plants get built by offering a guaranteed revenue stream for the purchase of electricity from the facility three years ahead. Having that power-purchase agreement improves financing options for developers.

Invenergy said the Nov. 19 FERC decision will not prevent the company from seeking a permit to build the Clear River Energy Center. Without the CSO, the company will simply sell its electricity independently into the wholesale electricity market.

“This ruling does not impact the future of the project or Invenergy’s commitment to Rhode Island,” Invenergy spokeswoman Beth Conley said.

The Conservation Law Foundation, an opponent of the power plant and in intervenor in the application process, argued that the loss of the CSO and a refusal by ISO New England to permit Invenergy from bidding either of its two turbines into upcoming CSO auctions means that the nearly 1,000-megawatt project isn’t necessary to meet current and future electricity needs.

Invenergy noted, however, that FERC made it clear that “need” was not the conclusion of the ruling and referred to FERC’s own words in the decision letter. “Our decision to accept ISO-New England’s request and deny Invenergy’s waiver should not be construed as a determination by the commission that the Clear River project is not needed, as that question is not before us.”

In a press statement, Conley noted that Invenergy was showing its commitment to the Burrillville power plant by announcing a new project with the Massachusetts gas and electric distribution company Eversource. The work expands Eversource’s transmission network across the border from Burrillville in Massachusetts and Connecticut to handle the added load of electricity.

The Energy Facility Siting Board is scheduled to hold a status hearing on the Burrillville power plant on Nov. 27. The regular hearings are scheduled to resume Dec. 5 at the office of the Public Utilities Commission, 89 Jefferson Blvd. in Warwick.