Survey of Energy Resources 2007
Wave Country Notes
At one time the UK had one of the largest government-sponsored R&D programmes on wave energy. After a period of reduction, interest has been renewed in recent years, with government-funded research at a number of universities and institutions as well as support for different device developers. There have been a number of initiatives that benefit the ocean energy sector in general:
development of a market pull price mechanism (similar to Portugal's). The Scottish Executive has confirmed a generous mechanism for the first wave energy scheme (which has already attracted one developer - OPD) and a decision on the price for the rest of the UK is expected shortly;
establishing a range of wave energy test facilities, ranging from wave tanks, dry-dock testing of large scale devices (e.g. the New and Renewable Energy Centre - NaREC - www.narec.co.uk/facilities-wave-and-tidal-dock.php), test stations for full size devices at sea (www.emec.org.uk) and a facility that will eventually provide a test station for small arrays of full-size devices at sea (the Wave Hub - www.wavehub.co.uk);
government support for developers of ocean energy devices in the form of direct grants and, more recently, a marine resources development fund of nearly US$ 100 million for pre-commercial devices;
support for wave energy through official organisations such as the Carbon Trust (www.thecarbontrust.co.uk). This has carried out an assessment of ocean energy devices, established a marine technology accelerator fund and invested in one wave energy device;
established coordinated academic research on wave energy in several universities (www.supergen-marine.org.uk).
Many different devices at various stages of maturity continue to be developed in the UK under the above initiatives. Among the leading developers are:
This company has developed the Oyster™, a near-shore bottom-mounted wave energy converter for use in water depths of around 12 m. It is an oscillating flap device, similar to the WaveRoller (see the Finland Country Note). It delivers pressurised seawater to the power take-off unit (i.e. conventional hydro-electric generators) on the shore. A full-size prototype device is being tested at EMEC (www.aquamarinepower.com).
C-Wave Ltd has designed a large wave-energy device in which buoyant vertical flaps or 'walls' are mounted via hinges on a long floating platform at a distance of approximately half an ocean wavelength apart. These flaps oscillate back and forth under wave action, activating a hydraulic pump mounted between each flap and the platform. The key innovation of this device is by using such a wide separation, the two flaps experience the peak and trough of a wave, thereby cancelling out any horizontal motion and reducing mooring loads. The device is still at the R&D stage (www.cwavepower.com).
University of Manchester Intellectual Property Ltd
The University of Manchester is developing the Manchester Bobber, which comprises 25-50 floating masses, suspended by wires below a platform in up to 60 m water depth. The masses rise and fall under the action of waves turning a pulley and its shaft in one direction (by using a freewheel clutch). This in turn drives an electric generator via a gearbox. The main advantage is that the pulley and all associated mechanical and electrical equipment are mounted on the platform above the waves. This device is at the R&D stage (www.manchesterbobber.com).
Ocean Power Delivery (OPD)
The technology behind OPD's Pelamis has been briefly described in the Commentary (www.oceanpd.com). It has been tested at full scale at EMEC and has contracts in place to deploy 3 devices in Portugal, 4 devices in Orkney and up to 7 devices at the Wave Hub in the UK. This is clearly the UK's leading device.
The ORECon concept is a floating OWC employing a multiple oscillating water column configuration (rather than the single chamber used by other OWC devices) and a self-rectifying impulse turbine. By combining multiple columns within the collector component, the device can be tuned to resonate at multiple rather than single frequencies to capture energy over a much broader waveband. This device is at the R&D stage.
Offshore Wave Energy Ltd (OWEL)
The OWEL is a very large floating platform containing several horizontal channels facing into oncoming waves, which have decreasing cross sectional areas as the waves travel down the channels. These trap the air between successive wave peaks and compress it before discharging into a reservoir, where it is then used to drive a turbine and thus generate power (www.owel.co.uk). This device is at the R&D stage.
Wavegen's pioneering shoreline OWC (the LIMPET) continues to function on the island of Islay. Its output is fed into the local grid but the plant also serves as a test bed for new technology. Wavegen has advanced plans for deploying such devices in Scotland and in Germany, as well as developing its OWC concept for use in arrays of small OWC chambers within breakwaters (www.wavegen.com).
This device consists of a floating buoy contained within a floating structure. The vertical movement of the buoy with the rise and fall of the waves is directly coupled to a linear generator on the platform (www.tridentenergy.co.uk). This device has been tested at NaREC and is still at the R&D stage.