The Government will announce the creation of the UK's first marine energy hub later as part of a push to speed up progress in the sector.
The South West Marine Energy Park will stretch from Bristol to Cornwall and as far as the Isles of Scilly.
Climate Change Minister Greg Barker told Sky News: "The potential for marine energy in the UK is huge.
"We believe there is as much as 27GW of electricity out there to be harnessed, that's the equivalent of eight nuclear power stations - a huge resource that is going untapped."
Marine energy is about harnessing the power of the sea - including big waves and tidal currents - to generate electricity.
Analysis released by the Carbon Trust in May last year showed the UK could create over 68,000 jobs in this emerging sector.
Sky News was given exclusive access to a new British wave power device, currently in development off the coast of Dartmouth.
The prototype SeaRaser was designed by British inventor Alvin Smith - a self-taught mechanical engineer, who learned everything he knows fixing cars in his dad's garage.
He said the device could produce electricity more cheaply than existing fossil fuels, adding the secret of his invention is its simplicity.
"It's really only a bicycle pump with a float on it," he said. "As this pump goes up and down it sucks sea water in and pumps sea water out, purely through the action of the waves."
It is effectively hydropower without the dam - using the rise and fall of the sea to pump water uphill, from where it can be released to drive a turbine and generate cheap, clean power.
Mr Smith said the device is relatively inexpensive and will do what no renewable technology has done before - make green electricity cheap.
Dale Vince, founder of UK renewable energy company Ecotricity, which has teamed up with Mr Smith to develop the device, said their calculations suggested it could be the "cheapest form of energy yet".
The first commercial SeaRaser unit - around 13 times the size of the prototype - is expected to be finished within the next 12 months.
Mr Smith said they hope to have 200 devices around the UK coast - enough to produce electricity to power a city the size of Liverpool - within five years.