A coal-fired power station is to close within a year amid rising costs in a move described as "devastating" for workers.
Energy giant SSE said that after a review it had taken the "difficult decision" to close its Ferrybridge plant in West Yorkshire by March next year.
The company said costs at the 48-year-old power station have been rising due to its age and it is forecast to lose £100 million over the next five years.
This, combined with the impact of environmental legislation and the political consensus that coal has a limited role in the future, make it unsustainable, said SSE.
Paul Smith, SSE managing director of generation, said: "This was a very difficult decision to take because of the impact on our Ferrybridge employees, their families and the community.
"It's been known for many years that the UK would have to phase out coal as it moves towards a more sustainable energy mix. We've sought to protect jobs and invest in the site to keep it running for as long as we possibly could but ultimately we've had to make this regrettable decision today."
SSE said it will redeploy the 172 workers affected by the announcement to other sites where possible.
Mr Smith said: "Our team at Ferrybridge is highly skilled, dedicated, with a strong track record of performance, and we're keen to ensure, where possible, that staff are redeployed across other parts of the SSE group, for example at the nearby Keadby power station, or across the wider business.
"We appreciate it is a concerning time for our employees and our priority is to support them over the coming weeks and months and ensure they have a range of options available to them for the future."