The UK government has today given the clearest signal yet that it is serious about significantly bolstering the UK's renewables capacity, unveiling proposals that would see vast swathes of the country's coastal waters used for offshore wind farms.

Speaking to the European energy industry at a conference in Berlin, business secretary John Hutton said that the UK would open up its seas to 33GW of offshore wind energy, enough to power 25 million homes by 2020.

Currently, eight gigawatts of offshore wind capacity have been approved, including the one gigawatt Thames Array project, but the new plans would see an additional 25GW added by 2020.

Hutton said that the proposals would be subject to a Strategic Environmental Assessment, but argued that if approved, the plan would make a significant contribution towards meeting the EU's target of generating 20 per cent of energy from renewables by 2020 and provide power equivalent to that used by all the UK's homes.

"The UK has some of the best offshore wind resource in the world, a long history of design, installation and operational expertise in the offshore environment and the skills and manufacturing capability to transfer to this exciting new sector," he said. "The challenge for government and for industry is to turn this potential – for our energy and economy – into a cost-effective reality. This will be a major challenge."

The proposed expansion of offshore wind is expected to focus on the North Sea, western Scotland and possibly even the Channel and will open up "the vast bulk of the UK's continental shelf to large-scale development".

To help drive the development of the proposed wind farms, the government said that in addition to bolstering subsidies for offshore wind, tidal and wave power through its renewables obligation scheme, it would also instigate a new regulatory regime designed to make it easier for offshore wind farms to connect to the onshore grid.

Separately, Hutton also announced he is to chair an expanded Renewable Advisory Board that will have access to a larger number of renewable energy experts and will provide advice to the government on how best to meet its renewable energy targets.

The proposals were welcomed by the British Wind Energy Association (BWEA), which last month released a report predicting that the UK would soon overtake Denmark as the world's largest provider of offshore wind power and had the potential to dominate the global market for offshore wind technologies.

"We welcome the Government’s effort to place wind energy on a sound footing and promote Britain into a leader in this sector," said BWEA chief executive Maria McCaffery. "This expansion will mean that by 2015, the UK's offshore market will be twice the size of any other national offshore wind market."

However, the proposals will have to overcome several major barriers if they are to become a reality. The cost of offshore wind turbines has soared in recent months because of shortages of many turbine components and experts insist a major increase in production capacity will be required to meet soaring demand.

Meanwhile, concerns over disruption to shipping, wildlife and coastal views mean plans that would hand over vast swathes of coastal waters to offshore wind farms would face considerable opposition.