Foreign-owned firms today seized the lion's share of the development contracts to kickstart a wind revolution in offshore Britain that ministers say will eventually match the glory days of the North Sea oil industry. But Gordon Brown said he was still confident that UK supply firms could win many of the £75bn-worth of contracts needed to build enough clean power to generate 25% of the country's electricity.

Nine wind power consortiums have signed agreements with the Crown Estate, which has responsibility for renewable power in UK waters, to take their proposals through the planning stage.

Only five of the nine have British companies involved in the partnerships – two of those with minority stakes – and the pace was largely set by Germany with E.ON, RWE and Siemens, who were all substantial winners. Centrica, the parent group of British Gas, was the only British group with a majority holding in any of the winning consortiums, but Scottish Power and SSE Renewables took a stake in development areas such as the Dogger Bank and Firth of Forth.

The proposed windfarms will be further away from the coast and in deeper waters than any existing offshore project, and therefore more difficult to build. But they will also be far less likely to be held up by planning objections that have blighted the development of onshore wind power.

Britain already leads the world in the deployment of offshore wind and has more projects installed, in planning or in construction than any other country.

But the issue of British jobs has become politically sensitive since E.ON awarded 90% of the £2bn-worth of supply contracts for the world's biggest windfarm – the London Array off Kent – to German and other overseas firms.

Brown said the new round of wind licences provided a substantial platform for investing in local industrial capacity. "The offshore wind industry is at the heart of the UK economy's shift to low carbon and could be worth £75bn and support up to 70,000 jobs by 2020," he said, adding: "I am definitely going to do everything I can to bring these jobs to Britain."

The business secretary, Lord Mandelson, and the energy and climate change secretary, Ed Miliband, were similarly upbeat, saying there were already engineering and other companies around the UK gearing up to win a slice of the action. Miliband said it would damage British companies' exports if the government at home insisted developers used UK suppliers.

Many of the developers represented at the contract awards in London expressed their own optimism that UK firms could rise to the challenge, but made clear they would press on regardless. Eddie O'Connor, chief executive of Mainstream Renewable Power, a partner of Siemens on the Hornsea zone, said: "We have to buy the cheapest wherever you can get it."

The new windfarms announced should produce as much power as eight Drax coal-fired stations.

Today's were welcomed by Greenpeace, which said the technological challenge should be relished.

"Throughout its history Britain has shown the determination and ingenuity to tackle the great industrial challenges of each era. In the 21st century these qualities are being called on once again, to enable the transition from fossil fuels to clean, renewable sources of energy. Our country is home to some of the best engineers, mechanics and construction professionals in the world. Their expertise will be crucial if we are to harness the massive potential that new technologies like offshore wind have to offer," said Greenpeace executive director John Sauven.

But while ministers and the developers were excited about the prospects of making a substantial difference to Britain's security of supply as North Sea oil and gas run out, as well as helping beat UK climate change targets, they also acknowledged the scale of the difficulties. The Crown Estate said it hoped to see 32GW of new wind power come on stream, but set no minimum, and its director of marine estate, Rob Hastings, admitted that "it depends on what we encounter" on the way.

O'Connor said there were potentially "millions of problems" but he was confident that none was insuperable. He singled out skills shortages and the need for a supergrid linking power networks around the North Sea to make up for the intermittent nature of wind.

Wind developers say research and development breakthroughs were also vital if the economics of wind were to improve sufficiently offshore. The government has spent £170m on grants for R&D but is still struggling to convince a major wind turbine developer such as Siemens or Mitsubishi to establish a blade manufacturing plant in the UK.

The £75bn challenge

The vision of building 6,500 turbines in deep waters around Britain that will generate enough power to provide 25% of the country's electricity is an exciting prospect, but a tough challenge.

Many developers admit it will only make financial sense – even with big government subsidies – if technological breakthroughs are made to drive down the £75bn-£100bn estimated cost. That could involve designing gigantic new blades or using new floating platforms on which seven or eight turbines could be erected, as is being pioneered by Swedish firm Hexicon.

Mainstream Renewable Energy, one of the development licensing winners, argues that the goal of producing 32 gigawatts of power offshore will also only be credible if a supergrid is built.

That could cost up to £15bn to link Britain with Norway and the continent using giant electrical cables through which power could be imported or exported depending on whether the wind was blowing, and which firm needed power at any one time. ­Denmark's offshore wind sector already produces too much power during some parts of the day and exports it to other countries.