91Èȱ¬

An economist has described the Scottish government's renewable energy targets as "unachievable".

The SNP wants all of Scotland's electricity demands to be met from wind, wave and tidal power by 2020.

But Inverness economist Tony Mackay said the country would continue to rely on fossil fuel-powered stations.

The government said his analysis was wrong and there were already projects built, under construction and planned to meet almost 60% of Scotland's needs.

Mr Mackay comments follow the publication of his review, Prospects for Scotland's Energy Industries 2011-2020.

He told 91Èȱ¬ Radio Scotland there would be an increase in wind projects over the next few years, followed by wave and tidal power projects.

However, Mr Mackay said: "There is absolutely no way we are going to get 100%. My best forecast is about 40% at the moment.

"At the moment about 80% of the electricity in Scotland is generated by two nuclear power stations, two coal-fired stations and the gas-fired power station at Peterhead.

"We will always need them for what's known as baseline load generation."

Mr Mackay said while fossil fuel-powered stations' contributions would fall, wind farms could not be depended upon for electricity use during peak times.

He said: "It's variable. Some days when it is not windy there is no electricity from them."

First Minister Alex Salmond unveiled SNP plans for all Scotland's electricity to be met from renewable energy by 2020 during the Holyrood election campaign.

A Scottish government spokesman said: "By 2020, Scotland will be generating double the amount of electricity we need, with additional electricity generation met by clean energy plants progressively fitted with carbon capture and storage technology.

"Our target for 100% of Scotland's electricity to come from renewables by 2020 - one of the most ambitious in the world - seizes the vast opportunities to create tens of thousands of new jobs as well as billions of pounds of investment into our economy."

He added that the government would shortly produce its renewables roadmap, setting out actions to meet Scotland's electricity, heat and transport targets.