A power station will close after around five decades of power generation.
Aberthaw B Power Station is last coal-fired power station in Wales and currently employs 170 people.
The owner RWE said it plans to close the station near Barry at the end of March next year.
It said the decision to close the station will contribute to the company’s goal of reducing CO2 emissions.
The union, Prospect said the closure will "hit the staff who work there hard".
In 2017, hundreds of protesters marched on the station, calling for its closure, and more investment in green jobs.
Today, Friends of the Earth Cymru has welcomed the news of the plant's closure.