An independent Scotland could reap a £30bn dividend from a "reindustrialised" green energy sector over the next 20 years, Alex Salmond said on Wednesday night, raising the stakes in his economic case for a break from the union.

The first minister told an audience of academics, students and members of the public at the London School of Economics Scotland's "unparallelled energy resources" would give a fully independent Holyrood "a huge competitive advantage" over the rest of Europe.

Salmond also said if Scotland had had full fiscal control since 1979, the nation would now have assets worth between £87bn and £117bn.

"Under independence we would make the best use of our unparalleled energy resources," he said. "We have 25% of Europe's tidal power potential, 25% of its offshore wind potential and 10% of its wave power potential – not bad for a nation with less than 1% of Europe's population.

"Scotland has a huge competitive advantage. We will be able to produce energy better and cheaper than anywhere else – and in deeper waters".

Salmond cited research by the thinktank Reform Scotland that suggested Scotland could export half the electricity generated by 2020 because of the Scottish government's renewable energy targets.

He said: "Reform Scotland estimates that as a result of our renewable electricity target Scotland would export half the electricity generated by 2020, increasing Scottish exports by £2 billion a year – equivalent to around 17% of Scottish manufacturing exports to the rest of the UK.

"And while renewables will be the source of Scotland's reindustrialisation, in value terms there is at least as much oil and gas still to come out as has already been used - at least 40 years of oil and gas reserves. We still have an opportunity to establish an energy fund.

"If Scotland had been independent in 1979, oil revenues could have reduced our public sector debt from 39% GDP in 1979 to 0% by 1983-84, and we would then have continued to run budget surpluses throughout the late 1980s.

"If we had been able to establish a sovereign wealth fund as North Sea oil revenues started to come on stream, then it is likely that Scotland would currently have financial assets worth anything from £87 billion to £117 billion pounds.

"The debate about independence is about looking forward and creating a better future for Scotland. With that future in mind, we still have an opportunity to establish an energy fund to benefit future generations. Even just £1 billion a year – less than 10% – invested over 20 years, would create a fund for Scotland worth almost £30 billion.

"An independent Scotland would pursue policies of ambition and responsibility. We would use Scotland's natural resources and skilled workforce to build a sustainable economy.

"The rest of the UK has much to gain from the emergence of a secure, prosperous ally to its north. An independent Scotland would seek to make a responsible contribution on the European and world stage - and that would benefit all of the nations of these islands."

David Cameron is to give a speech on Thursday in which he is expected to make a case in support of the Union, after which he will hold talks with Salmond.