The growing marine energy industry yesterday appealed for £80 million of investment to realise the potential of wave and tidal power and secure 12,000 jobs for Scotland which might otherwise go abroad.

At a major conference in Edinburgh, trade body RenewableUK said the £18m advanced to date from Holyrood and the £20m from Westminster amounted to less than one-third of the £120m needed to develop and commercialise wave-power technology.

Energy Minister Fergus Ewing told delegates he hoped the Green Investment Bank (GIB) would look again at its reluctance to fund small, early-stage projects in the emerging technology rather than large, low-risk wind farms.

Also yesterday, European energy company Vattenfall signed up to the last remaining berth for testing the Pelamis Wave Power machine in Orkney's European Marine Energy Centre.

The State of the Industry report, published by RenewableUK, says every £1 of public sector cash will unlock £6 of private investment, "assisting greatly in the achievement of Scotland's energy target of 100% electricity equivalent to come from renewable energy sources by 2020".

It says marine energy could provide 20% of UK electricity consumption, while Scotland boasts 25% of tidal and 10% of wave power across the EU, with 1.6 gigawatts of projects in the pipeline, largely in the Pentland Firth and Orkney.

It predicts that the sector will be worth £3.7 billion to the UK by 2020, creating 12,000 jobs, if it meets the UK Government's target of generating 300 megawatts. Last year it generated less than 8 megawatts.

At the report's launch, industry leaders said the past year had seen a breakthrough in credibility for the sector, but they also admitted that funding would depend largely on big corporates and the GIB, with consequent uncertainties.

Jeremy Biggs, of Narek Capital, said the GIB's attitude "sends out quite a clear signal to the private finance community", at a time when industry and angel funding was getting increasingly difficult.

David Krohn, RenewableUK's wave and tidal development manager, said: "It's frustrating that ministers have not yet identified marine energy as a priority sector for the GIB."

However, he said the arrival of industry players such as Alsthom, Siemens, ABB and Rolls-Royce, meant the technology would be developed.

Maria McCaffery, the body's chief executive, said: "An overly cautious approach could allow other countries to steal Scotland's lead, so it's vital the Scottish and UK governments build on the good work they've already done by supporting the these industries, to ensure we can retain our leading position globally."

Alan Mortimer, head of renewables for ScottishPower, said the utility wanted to be an early mover as it was in wind power. "We are seriously interested in this sector, we have already invested over £10m and we are looking at bigger investments as things move on."

He added: "There is a huge amount of effort going on, the challenges of the marine environment are big but the determination is there because of the potential - the big OEMs (original equipment manufacturers) are coming in."

Rob Hastings, of conference sponsors Crown Estate which leases the seabed, said: "What we have got to do is provide the investor community with a degree of certainty."

Rob Stevenson, chief executive of Rolls-Royce subsidiary Tidal Generation, said the engineer had been developing turbines for the sector for five years but needed to see a return on investment.

The experts said one of the problems had been that development had started before grid connections had been thought about, though one answer now appeared to be "piggybacking" off wind-energy connectors for installations that were not too remote.