Department of Energy Mandates Centralia Unit 2 Remain Available for Operation for Additional 90 Days

CALGARY, Alberta, Sept. 14, 2026 (GLOBE NEWSWIRE) — TransAlta Corporation (TransAlta or the Company) (TSX: TA) (NYSE: TAC) confirms that its subsidiary, TransAlta Centralia Generation LLC, has received an order (The Order) from the United States Department of Energy. The Order mandates that Centralia Unit 2 in Washington State remain available for operation, for a period of 90 days, until December 12, 2026.

Once in effect, TransAlta will continue to comply with the Order and to work with the U.S. Department of Energy and Washington state government in relation thereto.

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TransAlta is one of Canada’s largest publicly traded power generators, delivering reliable electricity across Canada, the United States and Western Australia. For more than 115 years, our people have safely operated and evolved essential energy infrastructure that powers customers and communities. Our technology-diverse portfolio and disciplined execution allow us to deliver dependable power across evolving energy systems. We take a practical, responsible approach to meeting today’s energy needs while building for what comes next.

For more information about TransAlta, visit our web site at transalta.com .

This news release includes “forward-looking information,” within the meaning of applicable Canadian securities laws, and “forward-looking statements,” within the meaning of applicable United States securities laws, including the Private Securities Litigation Reform Act of 1995 (collectively referred to herein as “forward-looking statements”). Forward-looking statements are not facts, but only predictions and generally can be identified by the use of statements that include phrases such as “may”, “will”, “believe”, “expect”, “estimate”, “anticipate”, “intend”, “plan”, “forecast”, “continue” or other similar words. Forward-looking statements are intended to provide the reader information about management’s current expectations and plans and readers are cautioned that such information may not be appropriate for other purposes. Forward-looking statements are subject to important risks and uncertainties and are based on certain key assumptions. All forward-looking statements reflect TransAlta’s beliefs and assumptions based on information available at the time the statements were made and as such are not guarantees of future performance. As actual results could vary significantly from the forward-looking statements, you should not put undue reliance on forward-looking statements and should not use future-oriented information or financial outlooks for anything other than their intended purpose. We do not update our forward-looking statements due to new information or future events, unless we are required to by law.