RENEWABLE energy, power-saving technology and the expertise that goes with it is now worth half a billion pounds to the Westcountry economy and supports companies employing more than 7,000 people, according to a new report.

The value of green power alone has rocketed by 550 per cent to £215 million per year in the last four years, according to green energy agency Regen SW. In 2005, the sector was worth just £34 million.

At a time when other sectors are shedding jobs, the number of people working in the renewable energy sector increased 40 per cent in the last year.

The news came as the Conservatives revealed that a major marine energy plant could be built in Cornwall under their ambitions to trigger a "big bang" in green technology.

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A summit will today see the Conservatives unveil initial plans for the county to become a world leader in harnessing the power of the sea.

If support from local businesses, scientists and residents can be built into a "coalition" the multi-million pound plan could be one of the first announcements of a Conservative administration.

Renewable energy and energy efficiency, combined, now total more than 300 companies, employing 7,200, bolstering the growing campaign to promote the South West as the home of the UK's green energy industry.

Matthew Spencer, chief executive of Regen SW, said: "Renewable energy businesses in the South West are growing at a very impressive rate, and are bullish about the future. The survey suggests that there continue to be opportunities for entrepreneurs setting up new businesses, or diversifying into renewables. This is good news for the region's economy, because these are generally firms that create well paid, high-skill jobs, with high levels of productivity."

The report, Economic Contribution of the Renewable Energy and Energy Efficiency Sectors in the South West of England – commissioned by Regen SW and carried out by DTZ – also showed wind is the largest renewable energy employer in the region, with 32 per cent of all renewable energy employees. A further 23 per cent of firms are involved in the wind sub-sector of associated industries.

The renewables sector is still dominated by small businesses, and 90 per cent of them expect their firms to grow either very strongly or gradually over the next few years.

In addition, 75 per cent of businesses said they expect to increase employment over the next few years, and over 60 per cent said they will recruit and train new managers or staff, expand existing UK markets, or develop new UK markets.

Mr Spencer added: "The energy efficiency sector is the poor cousin of renewables. It delivers huge carbon savings to our economy, but energy efficiency businesses get much less attention than those in renewables.

"Thanks to additional support from the South West Regional Development Agency, Regen SW is now able to provide networking and promotion opportunities to these firms. We're also committed to joining up and championing the best energy-efficiency initiatives in the region, which are vital to shrinking the South West's carbon footprint."

The Conservatives yesterday outlined how they see Cornwall as a frontrunner to be home to a Marine Energy Park to act as a hub for developing technology, bringing inventors, scientists and experts together and offering a direct connection to the national grid.

It would build on work already under way at the Peninsula Research Institute for Marine Renewable Energy (PRIMaRE), hosting developments from small-scale university trails through to full-scale commercial projects, attracting highly-skilled jobs and regenerating coastal areas.

Last night shadow energy secretary Greg Clark told the Western Morning News: "If you look at the potential that we have in the Westcountry and the Cornish peninsula in particular, the tidal and marine resources are literally second to none."

The Tories want marine technology to play a significant part in "ramping up" the amount of energy generated from renewable sources. At present, just 1.5 per cent of the UK's energy currently comes from green sources, with a government target of reaching almost 15 per cent by 2020.

The Tories point to figures which show we lag behind the rest of Europe, except for Luxembourg and Malta.

Mr Clark condemned Labour's "shocking record" on developing renewable energy, adding: "We have some of the best renewable resources in the world, in terms of wind, wave and tidal – yet we have an abysmal record.

"If we are to meet our climate change targets and we are to become less dependent on fossil fuels … we are going to need to spread where we get our energy from.

"If we were to be elected, we want to start with a bang rather than drag things out for years. We have been thinking for some time that Cornwall is a natural place for a marine energy park.

"This is an exciting opportunity for the region and starting to make the case, given that we want to get on with this very quickly, is a good thing to do."

Millions would be poured into the site, from central government, councils and private companies. The funding from Whitehall would be on a "serious scale".

The summit at the Combined Universities for Cornwall's Tremough campus, Penryn, will see Mr Clark and other senior Tories hold talks with green energy firms and others about Cornwall drawing up a bid to become home to the first Marine Energy Park if David Cameron wins the election, expected next year.