New wave generator brightens ocean power prospects

| 27th October 2014
An artist's impression of the Searaser at work. Photo: DWE Ltd.
An artist's impression of the Searaser at work. Photo: DWE Ltd.
A new wave power generator has moved closer to reality after successful testing in simulated marine conditions. An array of the 1.5MW 'Searaser' devices could be deployed on Britain's coast within a few years.
We believe these 'Seamills' have the potential to produce a significant amount of the electricity that Britain needs, from a clean indigenous source.

Generating electricity from the waves in Britain took a step closer to reality this week after an innovative device - Searaser - successfully completed its first stage testing.

A 1:14 scale model of the device went through exhaustive tests at Plymouth University's CoastLAB wave tank to verify its computed outputs in Britain's coastal waters, and to ensure its sturdiness under extreme sea conditions.

The brainchild of British inventor Alvin Smith, Searaser is designed to overcome two of the biggest hurdles in the deployment of renewable energy on a scale that fulfils Britain's future electricity needs - cost and variable output.

Green energy company Ecotricity and the Searaser team have spent the past 18 months optimising the design of the device and modelling outputs in real word conditions around the coast of Britain - with the assistance of marine energy consultants DNV GL Group.

Resilience to extreme conditions is essential

The determining factor in making wave power viable is resilience to often violent sea conditions, said Smith: "We've put Searaser through the most extreme testing regime here at CoastLAB and it's passed every challenge."

"This week's wave tank testing was carried out to validate the extensive computer modelling we've been undertaking", he added.

Unlike other marine energy technologies, Searaser won't generate electricity out at sea but will simply use the motion of the ocean swell to pump high pressure seawater ashore, where it will be used to make electricity.

The motion of the waves drives a piston between two buoys - one on the surface of the water, the other suspended underwater and tethered to a weight on the seabed.

As waves move past, the surface buoy moves the piston up-and-down, pumping volumes of pressurised seawater through a pipe to an onshore hydropower turbine to produce electricity.

The Searaser could also be used to pump seawater into coastal reservoirs elevated well above sea level. The stored water could then be released at any time of the day or night to make renewable electricity on demand.

The sea could produce a significant proportion of the UK's power

Ecotricity founder Dale Vince said: "Our vision is for Britain's electricity needs to be met entirely from our big three renewable energy sources - the wind, the sun and the sea.

"Out of these three energy sources, generating electricity from the sea is by far the most difficult due to the hostile ocean environment - it's also the least advanced of the three technologies but it has enormous potential.

"We believe these 'Seamills' have the potential to produce a significant amount of the electricity that Britain needs, from a clean indigenous source and in a more controllable manner than currently possible."

Ecotricity hopes to have a full scale prototype in the ocean in the next 12 months or so, measuring some 12m deep and 1m wide. A first commercial array of 'Searasers' could be producing electricity within a few years. Each device will be rated at 1.5 MW electrical capacity - similar to a large wind turbine.

"The potential is enormous", said Dale. "This is a British invention that could transform the energy market not just here in Britain but around the world. Our plan is to develop the technology and make them here in Britain, bringing green jobs as well as green energy to our country."

Ecotricity now powers almost 150,000 homes and businesses from a growing fleet of wind and sun parks. The company prides itself on building more green electricity generation capacity than any other energy company in Britain.


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