Fifty firefighters have tackled a blaze in a turbine hall at a power station.
Crews called to the site in Ironbridge, Shropshire, waited more than an hour to begin tackling the fire with water while the electricity generating turbines were isolated.
The fire service said there had been no reports of injuries after the blaze in Buildwas Road began at about 06:00 GMT.
There had been no pollution into the River Severn as a result of the fire, the Environment Agency said.
Energy company E.On, which runs the site, said the fire had been brought under control and it would be carrying out a full investigation.
A spokeswoman for Shropshire Fire and Rescue Service said the fire was located in one of the bearings of the main turbines and confined to the turbine hall.
Earlier fire officer Guy Williams said the fire service was using significant resources to try to bring the fire under control and prevent any environmental damage, and particularly to prevent water from the site reaching the nearby Severn.
He said the cause of the blaze was not yet known.
There was a minor fire in a wood pellet store at the plant on 3 October.
The power station, originally coal-fired, was converted to burn wood pellets last year ahead of its planned closure in 2015.
It can generate enough electricity to power the equivalent of up to 750,000 homes.