Gurit (Isle of Wight, U.K.) has secured an agreement with Pulse Tidal (Sheffield, U.K.), a tidal stream power provider that specializes in sourcing energy from shallow waters, to engineer, supply tooling and manufacture the composite blades for the latter’s Pulse Stream 1 MW demonstrator. Pulse Tidal has been granted €8 million ($11.5 million USD) from the European Union’s Framework Programme 7 technology research and development fund, enabling the company to begin work immediately on its first commercial-scale tidal energy generator. Although the project site has not yet been selected, Pulse Tidal predicts that the 1 MW generator will be commissioned in 2012 and will provide electricity for as many as 1,000 households. The project follows up success with a 100 kW test rig located in the Humber Estuary, near Grimsby, U.K., which supplies power to a chemicals company positioned on the river bank.
In addition to Gurit, Pulse Tidal has signed contracts with several other international companies to secure its supply chain for volume production. Supply chain partners, including the Fraunhofer Institute (Munich, Germany), also will provide technical support in the development and production of the technology.
The commercial tidal-energy machine will differ markedly from conventional water turbines. The blade diameter of a conventional horizontal-axis water turbine is limited by the water depth, which then limits the potential for power generation. Pulse Tidal’s system is better adapted for shallow water. It features a “flat” design based on twin composite hydrofoils positioned across the tidal flow, thus imposing no physical limit on blade length (see illustration). The system harvests the energy created as tidal streams move the blades up and down. The water flow alternately creates the upward and downward force in the same way that air moving over a wing provides lift, as the machinery changes the angle of the blade foil. This motion is converted to rotate a driveshaft that turns a conventional generator mounted above the water surface. The full-scale concept is based on four blades at approximately 20m/65.6 ft in length. The blades will be instrumented, enabling Pulse Tidal to verify actual loads during operation. The data will be analyzed for future optimization of the hydrofoil structure.
Gurit’s role will include working closely with Pulse Tidal and the other consortium members throughout the process to ensure that all integration issues are addressed in the early phases. Gurit was selected because of its experience in the wind energy, marine and offshore sectors and its interest in advancing tidal energy technologies that are efficient, scalable and cost-effective, says Thomas Royle, head of Gurit’s Strategic Business Development. “The Pulse Stream technology fills a unique niche in the industry to exploit both deep and shallow water sites and has now been proven at mid-scale,” he notes, pointing out, “They will be built using production blade techniques and materials to enable rapid and cost-effective roll-out for the first device farms.”