Attempts by Scottish ministers to clean up coal so it can replace nuclear power will lead to massive amounts of pollution and wreck the government’s targets to combat climate change, it has been claimed.

A new study predicts that the £2 billion “clean” coal plant proposed for Hunterston in North Ayrshire would end up belching out over 100 million tonnes of carbon dioxide (CO2) into the atmosphere over its lifetime.

Last week, the UK Government gave the go-ahead to 10 new nuclear power stations across England and Wales. There were none proposed for Scotland because of opposition from the SNP.

Instead, Scottish ministers want to build new coal-fired power stations, fitted with carbon-capture and storage technology to curb pollution.

On Monday, the Scottish finance secretary, John Swinney, announced that any new coal-powered station would have to capture-carbon 300 megawatts of its electricity generation from the first day of operation.

But the new coal plant planned at Hunterston by Clydeport’s owners, Peel Holdings, is going to generate 1600 megawatts of electricity. This means that up to 80% of the plant’s energy production will cause pollution as usual.

According to an expert analysis for the World Development Movement (WDM), this will see over 100 million tonnes of CO2 released into the atmosphere over 40 years. The campaign group is concerned this will worsen the plight of poor countries already affected by floods and droughts caused by climate change.

The WDM’s Scottish campaigner, Liz Murray, said Mr Swinney is being far too timid on carbon-capture and storage.

“It is nowhere near ambitious enough to ensure the kind of cuts in carbon dioxide that are needed to meet the targets set in the Government’s climate change legislation,” she said.

“There can be no place for new coal power in Scotland, unless it is fitted with 100% carbon-capture from day one. In the same way that the Scottish government went one better than Westminster with its climate-change targets, it should now also aim to show them what is possible by completely ruling out dirty coal.” The Scottish Government, however, dismissed the warnings about coal pollution as “speculation”. Scotland is determined to become Europe’s leader on carbon-capture and is working to create a low-carbon economy, insisted the energy minister, Jim Mather.

“Our position strikes the right balance between short-term security of supply, ensuring demonstration of carbon-capture and storage technology and making progress towards our ambitious carbon reduction targets,” he said.

Mr Mather insisted that Scotland needed new coal-fired power stations, but not nuclear reactors. “New nuclear power stations are dangerous, expensive, unreliable and unnecessary,” he said.

But this has been dismissed as “incompetence and dogma” by the Scottish Labour leader, Iain Gray, whose East Lothian constituency includes the Torness nuclear power station.

He argued that without nuclear power, Scotland would have to import electricity, or rely on coal or gas.

“The rest of Britain will be less reliant on energy supplies from overseas and there will be substantial environmental benefits,” he said. “The SNP has let Scotland down.”

But according to one recent study, both the SNP and Labour could be wrong. It claims it is perfectly possible for Scotland not to build any new coal or nuclear-powered stations, but to rely on renewable energy sources instead.

The study, by Glasgow-based energy consultants Garrad Hassan, says that, by 2030, Scotland could meet between 60% and 143% of its annual electricity demand from renewable energy. Exactly how much depends on the levels of investment put into saving energy and boosting renewables.

“Our analysis shows that if you shut down Scotland’s nuclear power stations – and the old coal station at Cockenzie – you would still have enough electricity generation in 2030 to meet peak demand in Scotland under most scenarios,” said Garrad Hassan’s Paul Gardner.

“Of course it depends a great deal on how much electricity demand rises or falls, but it’s difficult to foresee a situation in which nuclear power stations would be essential north of the Border.”

This scenario is possible, argues Mr Gardner, because Scotland is “blessed with an abundance of wind, wave and tidal power”. In England, however, it “made sense” to build nuclear stations close to areas of high demand.

At the moment Scotland depends on nuclear reactors at Hunterston and Torness to generate about a quarter of its electricity. But Hunterston is due to close in 2016 and Torness in 2023.

Mr Gardner said the suggestion Scotland could end up relying on nuclear electricity from England was “somewhat philosophical”, and that in an average year there would likely be a net export of power from Scotland to England.

“There would be times, when the wind wasn’t blowing, that you would need to import power from England, but equally there would be other times when you would be exporting power to England,” he said.

This view was backed by the environmental groups which commissioned his analysis. The idea that Scotland would be reliant on imported nuclear power was “based on a fundamental misunderstanding of electricity generation systems,” said Friends of the Earth Scotland chief executive Duncan McLaren.

He also challenged the “propaganda” that nuclear power would be good for Scottish jobs.

“Far from creating sustainable employment, building nuclear power stations in Scotland would starve our renewables industry of finance, engineers, construction capacity and more,” he said.