Ministers have been urged to drop their block on subsidies for onshore windfarms, as industry figures showed that nearly 800 renewable projects are ready to plug much of the power gap left by the abandonment of the Wylfa nuclear project.

Hitachi dropped plans for the nuclear plant in Wales this week, raising questions over what would replace it and leading the business secretary, Greg Clark, to admit that renewable energy sources are more competitively priced than nuclear.

The wind industry said if a bar on onshore windfarm subsidies was lifted it would allow the construction of 794 projects which have won consent through the planning system and are ready to build. Together they would generate around 12 terawatt hours of energy a year; two thirds of what Wylfa would have produced.

A dozen firms are behind the schemes, including small players and big names such as Scottish Power, Vattenfall, E.ON, EDF Energy and npower’s owner Innogy. But onshore windfarm installations have stalled since the government banned them from securing subsidies.

Quick Guide Offshore windfarms in the UK Show How important is offshore wind power to the UK energy system?

Offshore windfarms generated 8% of the UK’s electricity in 2018, according to estimates by trade body RenewableUK. The UK has more offshore wind capacity than anywhere in the world, with 37 projects made up of nearly 2,000 turbines. There is nearly 8GW of capacity today, 1.3GW of which was added in 2018. Another 5GW is already committed to. The UK has 44% of all European offshore wind power capacity. What obstacles has wind power faced?

The first subsidies awarded to offshore windfarms promised developers a guaranteed price of up to £150 per megawatt hour, or roughly three times the wholesale cost of electricity. Such steep subsidies would not be sustainable but cost reductions in the industry have seen that figure drop to as low as £57.50. The offshore wind industry has previously been criticised for not using enough UK contractors and suppliers. What is the economic benefit to the UK?

The industry employs around 11,000 people. One of the side effects of offshore wind’s growth has been an injection of money and jobs into coastal towns that in some cases have big pockets of economic deprivation. Ports have been upgraded and new maintenance facilities built, such as the one at Newhaven in East Sussex for the first windfarm in the English Channel. The different parts of turbines are made across the UK, from the Isle of Wight to Hull. What does the future hold for offshore wind power in the UK?

The industry has a target of growing today’s 8GW capacity to 30GW by 2030, which, if achieved, would see offshore wind power supplying more than a third of the UK’s electricity. The government has put a £557m pot of funding aside for subsidies for renewables in the next few years, most of which is expected to be taken up by offshore windfarms. The industry is also hoping for export opportunities for UK firms, as new markets grow in the US and Asia.

Emma Pinchbeck, the executive director of RenewableUK, which compiled the figures, said: “We have ready-to-go onshore wind that can help close the gap between the low carbon power we need and the amount government policy is actually delivering, and this week’s announcement on nuclear power has made this mammoth task even harder.”

But she said the government had “stacked the odds” against building the onshore windfarms needed to hit the UK’s carbon targets, by excluding developers from competing for subsidies in auctions. Only offshore windfarms can compete for state funds currently.

The government’s figures show onshore windfarms are the cheapest source of new electricity generation. The Hinkley Point nuclear project in Somerset won a guaranteed price of £92.50 per megawatt hour, compared with £57.50 for offshore windfarms in the early 2020s. Experts think onshore windfarms could hit around £50 per MWh.

Labour said that Clark should match his comments on renewables with action. Rebecca Long-Bailey, the shadow business secretary, said: “The government point to renewable energy as an alternative to their failing plans on nuclear. But these figures reveal that the government is being equally reckless with onshore wind – the cheapest form of new renewable energy.”

The Scottish energy minister, Paul Wheelhouse, said that after the failure of Hitachi’s projects, it was time for the UK to prioritise onshore windfarms and other renewable technologies over nuclear.

The government’s infrastructure advisers, the National Infrastructure Commission, urged a rethink that would allow onshore windfarms to compete for support.

Energy analysts and renewable energy companies including BP-backed Lightsource have also written to the government urging it to allow onshore windfarms and large solar farms to secure a government-underwritten price for power from their projects.

But energy minister Claire Perry, who has hinted in the past year that a U-turn on the subsidy ban could be on the cards, appears to have cooled on the idea.

“Both I and the Scottish conservatives were elected on a manifesto that said there should be no more subsidy. We didn’t think subsidy for onshore windfarms is correct,” she told the Guardian earlier this month, when asked if there were plans for a rethink.

Perry said onshore windfarms had reached the point when they no longer needed to be subsidised, a claim not supported by industry. “I think we are getting to a subsidy-free point … The sense I have is that onshore wind deployment will continue without the substantial subsidy.”