UK energy secretary Ed Davey has warned electricity prices could rise in Scotland if it gains independence in the sector.
He said plans by the SNP government to increase the country's use of renewables would push up prices.
The authority north of the border wants to generate the equivalent of 100 per cent of the nation's power from green sources by 2020.
But Mr Davey questioned where the money will come from to fund this.
The Scotsman quoted him as saying: "Would it be consumers in England, Wales and Northern Ireland being asked to pay for the electricity generation from an independent Scotland?"
Scottish Power recently revealed it has successfully tested a new underwater system as part of the first consented tidal power project in Scotland.
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