LONDON (Reuters) - The promised vast expansion of the UK's offshore wind resources is proving to be a powerful lure for companies not normally associated with renewables but keen to generate eco-friendly and reliable sources of revenue.

Engineers, consultants and oil rig makers, from GKN to Lamprell and Singapore's Keppel, are setting up new divisions and partnerships in order to get a foothold in the market, which offers secure returns to those building and running the turbines.

Britain now has more offshore wind capacity than the rest of the world combined after Vattenfall opened its huge Thanet wind farm in the estuary of the River Thames yesterday.

"It's attractive for a lot of companies that are looking for contracts," said Ian Simm, chief executive of green fund firm Impax Asset Management, which has holdings in companies such as turbine maker Vestas.

"The fundamental point that makes it attractive is scale and government commitment, and the fact that industrial companies can learn the facts of success in one offshore environment and be able to transfer the majority, if not all, of those skills to other countries," he said.

Britain, aiming to get 15 percent of its electricity from renewable sources by 2020, this year awarded licences to wind farm developers in a programme that could deliver up to 32 gigawatts of generation capacity and require investment of over £75 billion.

However, that is just a small slice of what could be a very large pie if Britain were to make more of its abundant supplies of wind.

The Offshore Valuation Group, made up of government and industry organisations, estimates if Britain were to develop just 29 percent of its potential offshore resource, this could deliver 169 gigawatts of capacity by 2050 and turn Britain into a net exporter of electricity.

This would involve installing 7.2 GW a year — roughly equivalent to 1,000 7.5 Megawatt turbines — with fixed offshore wind accounting for 5.4 GW of the average annual build rate needed. The supply chain needed for this would have annual revenues of £62 billion in 2050 and employ around 145,000 people directly, according to the Offshore Valuation report. The supply of installation vessels, cables and turbines are among the key areas that need to be addressed, says Sarwjit Sambhi, managing director of power generation at Centrica, which has won the rights to develop up to 4.2 GW of offshore wind power in the Irish Sea.

The owner of British Gas is currently working on the 270 MW Lincs offshore windfarm and its next big project is Race Bank, which will be twice the size of Lincs.

"We still need to go through the procurement process (for Race Bank) and I'm encouraging that we do try and see how many new suppliers are out there and whether they're capable of delivering what we need," Sambhi said.

Both oil rig refurbishment specialist Lamprell and SeaEnergy , which has switched into wind farms from oil and gas, are hoping to take advantage of the expected boom in demand for vessels, with Lamprell saying it is extremely busy on the bidding front in this area..

The main competitors in this field are expected to come from Asia, home to companies such as Keppel, the world's biggest maker of oil rigs, and Hyundai Heavy Industries, the world's largest shipbuilder.