The scaled 12.5:1 demonstrator model of the wave power conversion device is currently undergoing testing at a wave tank at the New and Renewable Energy Centre (NaREC) in Niorthumberland (
Ocean Treader is a floating device designed to be moored 1–2 miles offshore in ocean wave systems, and as such will be largely unobtrusive from the shoreline. The theory behind the machine has been proven in wave tank testing (projected p/KWhr is considerably lower than other WECs) and Green Ocean Energy is now working towards developing a full size machine for offshore testing.
Added value for off-shore power generation projects
Wave Treader stems from the work on Ocean Treader and consists of a machine designed for mounting on the foundations of a static offshore structure, typically a wind turbine or tidal turbine. The structure comprises steel load bearing members with the floating bodies molded from GRP (Glass Reinforced Plastic). This allows standard offshore manufacturing techniques to be used, and, importantly, a wide range of fabrication yards across the world. The device promise to be highly commercially attractive, have low technical risk, and be quick to market.
By sharing the high infrastructure costs with another device, such as the foundation costs, cabling costs, etc., the economics of both Wave Treader and the wind or tidal turbine are enhanced and the energy yield for a given sea area greatly improved, while an initial study commissioned by Green Ocean Energy indicates that the additional loads placed on the foundations of an offshore wind turbine from Wave Treader are relatively small, and therefore Wave Treader will not adversely affect the stability of the wind turbine.
Wave Treader and its close cousin, Ocean Treader, both comprise a Sponson at the front, a Spar Buoy in the center and a second Sponson at the aft end. As the wave passes along the device first the forward Sponson lifts and falls, then the Spar Buoy lifts and falls slightly less and finally the aft Sponson lifts and falls. The relative motion between these three floating bodies is harvested by hydraulic cylinders mounted between the tops of the arms and the Spar Buoy. The cylinders pressurise hydraulic fluid which, after smoothing by accumulators, spins hydraulic motors and then electric generators. The electricity is exported via a cable piggy-backed to the anchor cable. Both devices are directional and have been proven to passively weather-vane to face the wave train. They also have active onboard adjustment to allow for offset due to the effects of current.
Targeting the expanding offshore wind farm market
Wave Treader is primarily aimed at Round 3 offshore wind turbines which tend to be further offshore and in more vigorous wave environments than Round 1 & 2 machines.
According to the British Wind Energy Association report ‘UK Offshore Wind Energy: Moving Up a Gear’ 2007, between 2006–2010, 480 offshore wind turbines will be installed around the
Npower has supported a feasibility study into the commercial application of Wave Treader via their Juice Fund fund – a unique scheme that supports the development of wave and tidal technology. Helen Steed of npower commented, “We are delighted with the results of the Green Ocean Energy Wave Treader. The device is the first of its kind, and shows tremendous potential in utilising existing off-shore infrastructure to generate clean renewable energy. This is exactly the type of project that npower juice fund was developed for.”
Green Ocean Energy expects to build a full size prototype of Wave Treader in 2009 with commercialisation in 2011. Managing director of Green Ocean Energy, George Smith, who invented Wave Treader said, “We have drawn on our extensive skills and experience in the energy sector to develop this technology. The support we have received from npower through the juice fund has enabled us to take a huge step forward in preparing the device for widespread use in the offshore environment. These are exciting times for the company and we look forward to eventually seeing the device incorporated into offshore wind farms.”
The company is now looking to attract further investment to enable continual development of its products.
