THE Green Party has placed plans for a combined heat and power (CHP) station in Southampton on to the election battlefield.

As it officially launched its local elections manifesto, the party challenged city council candidates to show their green credentials by pledging to ditch plans to use palm oil to supply cheap heat to more than 3,500 Millbrook homes and nine schools.

The council's Liberal Democrat Cabinet this week revealed it had lined up a European operator to build and run the £50m dockland plant.

Council leader Adrian Vinson said the scheme offered "major prizes" for the environment and one of the "more deprived areas of the city".

But Ewan Organ, Green Party spokesman, said palm oil was the worst biofuel option available.

"It has to be transported from the other side of the world, leads to the destruction of precious rainforests and obliterates habitats for threatened species such as orang-utans," he said.

"Palm oil plantations create a monoculture unable to support the rich diversity of wildlife in places like Indonesia."

Mr Organ added burning palm oil near homes would worsen the already poor air quality in Southampton while storing the oil on site could mean a safety hazard.

He urged the use of locally-grown biofuel, adding: "The most fuel-efficient option is to use the money on better insulation for houses and other energy-saving measures."

The Green Party is fielding candidates in ten of the council's 16 wards.

Construction on the CHP plant could begin in the autumn. It could be heating homes by the end of 2008.

An earlier company chosen to operate it pulled out in September after doubts over the reliability of foreign supplies of vegetable oil.

It caused the loss of a £7.9m grant from the Energy Saving Trust, which the new operator will have to plug.

The council says the plant will save 170,000 tonnes of carbon each year. An average household emits six tonnes per year.