Workers at Drax power station in North Yorkshire - one of the largest in the UK - are today striking over pay, reported the BBC. It is the first strike of a planned nine.
The Unite union said about 180 staff had rejected an 8% pay offer, which it said was a real-terms pay cut, but the company said the deal was worth 10%.
A spokesman for the site told the BBC it was operating as normal, as the company downplayed Unite's claim its industrial action would "close Drax down".
The strike is the first of nine scheduled over the next three months, as workers hope to persuade management to improve their pay offer.
Further strikes are due to take place on 27 February, then on 6, 13, 20, 27 March and on 4, 10 and 17 April.
Drax declared its half-yearly profits had jumped from £52m to £200m year-on-year, with Unite accusing the firm of "classic corporate greed".
Unite regional officer Shane Sweeting said: "The strike action at Drax will inevitably cause considerable strain on the national grid but this dispute is completely of the company's own making.
"Drax has had every opportunity to make our members a fair offer, but it has repeatedly failed to do so."
A Drax spokesperson said: "Drax Power Station is continuing to generate renewable electricity for millions of homes and businesses as normal.
"We have put forward a generous, full and final pay settlement which rewards our valued colleagues with a significant pay rise worth 10% and a £2,000 lump sum.
"We are deeply disappointed that Unite has gone forward with this unnecessary action which means colleagues are losing money instead of securing a significant pay rise."
The company said it remained open to dialogue with Unite to end the industrial action.
"There are three trade unions representing colleagues at Drax Power Station and this offer has been accepted by Prospect, while GMB has stated it will not be taking industrial action," it added.
The spokesperson said the power station employed 471 production staff of which 185 took part in the ballot.
Drax staff striking over pay
