The Crown Estate today announced that 96 companies have registered their interest in the third round of bidding to develop offshore wind farms in nine zones around the UK.

The government hopes the projects will provide 33GW of energy and be developed by 2020, with construction beginning in 2015.

Business Secretary John Hutton welcomed the launch of the latest phase in the bidding process.

"The launch of the Crown Estate bidding competition is a huge opportunity for investors and developers to play a part in the renewables revolution sweeping the UK," he said. "Offshore wind could dramatically increase the amount of electricity generated in this country from clean, green sources."

The nine zones are yet to be completely finalised and are subject to a Strategic Environmental Assessment being undertaken by the Department for Business, Enterprise and Regulatory Reform (BERR), which should be finished by Spring 2009.

The assessment is currently looking into areas that have sea depths of up to 60 metres - twice as deep as current offshore wind installations.

These areas would pick up more wind than current offshore wind farms, but construction is far more difficult in deeper seas as boats need to be able to stabilise themselves on the seabed before they can begin to install the turbines.

The Crown Estate – formerly owned by the Monarchy - is a public sector property developer that raises funds for the Treasury. It owns more than half of the UK's nearshore coastal regions and, while it will not operate offshore wind farms itself, it will lease out the seabed to developers.

The Estate also announced today that it has opened up parts of the Pentland Firth - an area to the North of Scotland - for lease so that Scottish Power can develop a large tidal energy project.