PLANS for the UK’s first coal power station in a generation are a terrible idea, says one of the world’s most eminent climate scientists.

Speaking on Radio Four’s Today programme, James Hansen, a director at NASA, said that the plant, due to be sited next to an existing coal power station at Kingsnorth "will destroy the efforts of millions of citizens to reduce their carbon emissions".

He also argued that the biggest source of the global warming problem was coal.

The warning came as six Greenpeace volunteers appeared in Crown Court after shutting down the existing Kingsnorth power station in October last year. They were charged with aggravated trespass and criminal damage after scaling the 200-metre smokestack.

Joss Garman, of Greenpeace, said: "Scientific warnings don’t come stronger than this. But Gordon Brown still seems intent on ignoring the world’s leading climate scientist.

"The Prime Minister must ditch these disastrous plans for Kingsnorth 2 immediately."

Gordon Brown is set to give the green light to the plans in the coming weeks. The German company E.ON wants to start building the power station this summer.

If constructed, Kingsnorth 2 will pump out more than eight million tonnes of carbon dioxide every year – the same as the 30 least polluting countries in the world combined.

All 18 defendants had earlier pleaded guilty to the charge of aggravated trespass. None of them had links to Kent.

Fifteen of the defendants were ordered to pay £200 fines. The other three, who are students, were charged a reduced £150 fee. All 18 were also ordered to pay £75 costs to the court.

Fifteen demonstrators stopped conveyor belts carrying coal into the plant and chained themselves to machinery, while the other three barricaded themselves inside an oil store room.

A further six defendants, who are charged with aggravated trespass and criminal damage, are accused of climbing the chimney stack at Kingsnorth and painting the first word of a slogan ‘Gordon Bin It’ on the side, causing £31,000 damage.

The defendants pleaded not guilty to the criminal damage charge. They did not enter a plea to the aggravated trespass charge.