|The Oyster concept for transforming wave power to onshore electricity. Click to enlarge.|
A new type of wave power machine—Oyster—is being installed on the seabed off the Atlantic shores of the Orkney Islands for trials that begin this autumn. In contrast to many other wave power devices, Oyster uses hydraulic technology to transfer wave power to shore, where it is then converted into electricity.
Oyster is fitted with an 18m-wide oscillator based on fundamental research at Queen’s University Belfast led by Professor Trevor Whittaker. The oscillator is fitted with pistons and, when activated by wave action, pumps high-pressure water through a sub-sea pipeline to the shore. Onshore, conventional hydroelectric generators convert this high-pressure water into electrical energy.
The whole field of generating electricity from wave power is ground breaking, but Oyster technology is highly innovative because it relies on simplicity. Its offshore component—a highly reliable flap with minimal submerged moving parts—is the key to its success when operating in seas vulnerable to bad weather where maintenance can be very difficult. There is no underwater generator, power electronics or gearbox underwater to go wrong. All the complex power generation equipment remains easily accessible onshore.—Dr Ronan Doherty, Chief Technical Officer of Aquamarine Power, developer of the Oyster
|The Oyster prototype. Click to enlarge.|
Oyster is designed to be deployed at near-shore water depths of 12 to 16 meters, benefiting from the more consistent seas and narrower directional spread of the waves in this location. The reduced wave height and load enhance survivability and allow a high percentage of annual average power and consistent power delivery. Any excess energy is spilled over the top of the flap, its rotational capacity allowing it to literally duck under the waves.
The environmental risks associated with the device are minimized by using only water as its hydraulic fluid, rather than oil, and there are no toxic substances involved. It is also silent in operation. Based on figures from the Carbon Trust, each Oyster’s annual carbon saving could be as much as 500 tonnes.
Although at an early stage of development, the Oyster concept could have significant potential for use in many locations around the world.
Our computer modeling of coastlines suitable for this technology shows that Spain, Portugal, Ireland and the UK are ideal candidates in Europe. But globally there is huge scope in areas like the North West coast of the USA and coastlines off South Africa, Australia and Chile. We estimate that the potential size of the market could be in excess of £50 billion.—Ronan Doherty
Aquamarine has signed an agreement with Airtricity for the development of up to 1,000MW of marine energy sites by 2020 using Oyster technology.
In collaboration with Aquamarine, Oyster will be the sixth wave power sea trial for the Environmental Engineering Research Centre (EERC), Queen’s University Belfast. Research at QUB, which contributed to the Oyster technology, was supported by the Engineering and Physical Sciences Research Council, UK.
The EERC at QUB has also worked with Wavegen (A Voith Hydro company, earlier post) on the Limpet wave power machine.