Britain launches first major auction for offshore wind leases in a decade

* UK seeks third of electricity from offshore wind by 2030

* Renewable developers, oil majors likely to bid

* First licences could be awarded early 2021

By Susanna Twidale

LONDON, Sept 19 (Reuters) - Britain has launched its first major auction of offshore wind farm leases in a decade, offering sites with the combined potential to power more than six million homes.

Britain is already the world's largest offshore wind market, and plans to generate a third of its electricity from the technology by 2030 as a part of efforts to reach its 2050 net zero carbon emissions target.

The Crown Estate’s so-called fourth leasing round is expected to attract bids from established offshore wind developers as well as European oil majors, under pressure from shareholders to show how they plan to align their businesses with global efforts to cut emissions.

Shell said earlier this year in an interview with Reuters it would take an "active role" in the tender.

The Crown Estate, which acts as manager of the seabed around England, Wales and Northern Ireland said in a statement on Thursday that four broad areas of seabed would be made available to the market.

Combined, the sites have the potential to host a total of 7 gigawatts (GW) of electricity generation.

Companies will assess the areas available and then make their own proposals for project sites.

The Crown Estate will then asses the viability of the proposals, with the tender process beginning in October and expected to take around 12 months.

First seabed rights could be awarded in early 2021, The Crown Estate said.

Its last major licensing round for offshore wind took place a decade ago, with winners including Britain's SSE and Norway’s Statkraft announced in early 2010.

Britain currently has around 9.3 GW of operational offshore wind capacity, with around 8% of the country’s electricity coming from offshore wind in 2018.

It is also host to the world's largest fully operation offshore wind farm: Orsted’s 659 megawatt Walney Extension project.

Crown Estate Scotland is also set to launch an offshore wind seabed licensing round for sites off the Scottish coast in October. (Reporting by Susanna Twidale; Editing by Mark Potter)