The Crown Estate said that the figures included 60-70 billion pounds to be spent for wind turbines, 10-20 billion for power transmission systems and a further 10-20 billion for other items including the supply chain.
Rob Hastings, director of the estate, which owns the seabed 12 nautical miles off the British coast, told reporters that Round 3 leases were aimed at installing up to 25 gigawatts of offshore wind farms in addition to the 8 gigawatts from Rounds 1 and 2 which are now under way.
To meet its target of cutting carbon emissions by 80 percent by 2050 compared with 1990, Britain has launched a program to expand its offshore wind farms, already the world's biggest at around 1 gigawatt (GW), to around 33-40 gigawatts by 2020.
Roger Bright, the Crown Estate's chief executive, said that by 2020 about a third of Britain's electricity was expected to be generated by marine renewable sources, including offshore wind as well as wave and tidal energy like that to be generated by the Pentland Firth project off northern Scotland.
Britain now has total generating capacity of about 75 GW.
Hastings said the Estate would announce winning groups to develop the Round 3 offshore wind projects, which are divided into nine zones, by end-2009.
It expected the first turbine for the Round 3 projects to be in the water in 2014.
He said the Pentland Firth development, the first commercial project to harness energy from wave or tide, was likely to deliver 1 gigawatt (GW) more than the 700 megawatts (MW) initially envisaged by 2020.
It planned to announce winning developers next February.
Dermot Grimson, head of External Affairs, said the organization planned a competition to build and operate storage facilities for carbon emissions captured from coal power plants in 2010 or 2011.
This would make use of old gas and oil fields under the North Sea. The initial competition would be to store 2 million tonnes per year for 15 years, Grimson said.
Carbon capture and storage (CCS) is seen as one key to reducing carbon emissions from coal power generation but the technology is yet to be scaled up and proven commercially.