Energy companies will be forced to wind down coal-fired power stations more rapidly after a rare pincer movement in the House of Lords by the Liberal Democrats and Labour.
Peers voted by 237 to 193 in favour of a joint amendment to the energy bill compelling old coal-power stations to cut their greenhouse gas emissions.
The defeat came despite Baroness Verma, energy minister, warning it could undermine energy security and increase fuel prices.
But Baroness Worthington, shadow energy minister, said the country risked missing decarbonisation targets if there was not a “tool in our armoury’’ to tackle the emissions produced by old coal-fired power stations.
The vote could still be reversed when the bill returns to the House of Commons in the coming weeks.
If it remains in the legislation it will add to the pressure on the government which is already struggling to get enough new energy infrastructure built ahead of an expected capacity crunch in the next decade.
SSE, the power producer, has previously said that the plan could “exacerbate the capacity crunch” and put further upward pressure on the cost of producing energy.
Guy Shrubsole, an energy campaigner at Friends of the Earth, backed the move, saying that coal was a “19th century technology that has no place in the 21st century”.
Most of Britain’s coal power stations had been earmarked to close by 2023 under a European directive imposing limits on the release of sulphur dioxide and nitrogen dioxide. But some companies were looking to keep their plants open by upgrading them to filter out these gases.
Paying for upgrades could make financial sense because coal is cheap. At present, these old power stations will not need an “emissions performance standard” (EPS) – which restricts carbon dioxide emissions – because this only applies to newly built ones.
However, the Lib Dem amendment – put forward by Lord Teverson, energy spokesman – proposed extending the EPS to old power stations in a move that would make it impossible for them to keep operating at full throttle.
As a result, coal-fired power stations would be confined to generating back-up energy only when supplies run low.
Lord Teverson was able to oppose his own government because, despite being Lib Dem energy spokesman, he is not a minister – making for a highly unusual joint operation by the Lib Dems and Labour in the upper chamber.
The US has cracked down on the emissions of existing coal plants after an initiative by President Obama in June which angered the American coal industry.