Last Coal-Fired Plant in Washington State Converting to Natural Gas

The lone remaining coal-fired power plant in the state of Washington will shut down at the end of December, and will be converted to burn natural gas. Operator TransAlta Corp. on December 9 announced an agreement with Puget Sound Energy (PSE) for the transition, with a 16-year, fixed-price contract for the gas-fired generation that runs through 2044.

The plant in Centralia will reopen late in 2028, according to TransAlta, as a 700-MW gas-fired facility. The closure of Centralia Unit 2, the last coal-fired unit at the plant, was approved by Washington lawmakers in 2011. TransAlta said the coal-to-gas conversion will require a capital expenditure of about $600 million.

John Kousinioris, CEO and president of Canada-based TransAlta, in a statement said converting the plant to natural gas “will lower the emission intensity profile of the facility by approximately 50 percent. We are grateful for the constructive and solution-oriented engagement we have received from the Department of Ecology and other state and local regulatory bodies through the development of this project and we are well- positioned to receive required regulatory approvals in a timely manner.”

Kousinioris added, “This project demonstrates the valuable role that legacy assets can play in supporting the State’s clean energy laws and system reliability in a cost-effective and timely fashion.”

Former Washington Gov. Christine Gregoire, a Democrat who during her term (2005-2013) helped forge the deal with TransAlta, prior to Tuesday’s announcement had said she supported moving to natural gas to support baseload power in the state. Gregoire noted the importance of keeping the plant operating while more renewable energy projects are built. The site in Centralia also was home to a coal mine, the largest in the state, that was closed nearly two decades ago.

The agreement passed by state lawmakers in 2011 said the coal-fired generation at Centralia would end by year-end 2025. It also said the state would expedite a gas-fired facility at the site. The deal also called for TransAlta to provide $55 million for economic development projects around Centralia.

Kousinioris said, “Our Centralia facility has a long history of providing reliable and affordable power in the Pacific Northwest region. We are pleased to extend the useful life of this asset and support the ongoing reliability needs of PSE and, by extension, its customers.

“When the facility re-enters operations, it will generate long-term contracted cash flow for TransAlta, earning a full return on and of capital within the contract term,” said Kousinioris in his statement. “The Company is well-positioned to execute this project given our deep technical, operational and engineering experience gained in previous coal-to-gas conversions.”

—Darrell Proctor is a senior editor for POWER.