Harnessing the waves
Partners in an EU-funded project have developed a new wave energy converter, which they say can outperform other wave energy systems. To put their system to the test, the project consortium is building a full-scale prototype off the coast of Norway. The project could not come at a better time. With the threat of climate change increasingly becoming a reality, and a possible energy crisis looming, European policymakers are more and more interested in raising the share of clean, renewable energies in Europe's energy mix. The Seawave Slot-Cone generator (SSG) is a wave energy converter based on the wave overtopping principle, using a total of three reservoirs built on top of each other. The water captured in the reservoirs then runs through a multi-stage turbine for electricity production. The three-tier design allows for the capture of both large incoming waves, which create the most energy, and smaller waves which ensure continued energy production. 'The advantage of our concept is that it fully utilises the whole spectrum of waves, which ensures a high degree of efficiency and the continual generation of energy,' Monika Bakke of Wave Energy AS, the lead partner in the WAVESSG project, told CORDIS News. Another advantage to the converter is that it only uses one turbine. 'Normally for a system to catch different sizes of waves there would be one turbine in each pool [reservoir],' explains Ms Bakke. 'The problem with having individual turbines is that waves come and go; the gap between waves arriving causes the turbine and then the generator to stop. This then disconnects the system from the electricity grid.' The system patented by the project consortium uses just one common turbine wheel for all of the three reservoirs. 'So as long as one pool is producing energy, the converter will stay connected to the grid,' says Ms Bakke. Following intense lab testing, the project partners are now ready to put the converter to the test in a real-life environment. They have started work to integrate a demonstration converter into a harbour breaker at Kvitsoy, a small island (520 inhabitants) off the coast of Norway. Having studied the waves at the location, the project partners have adapted the converter to harness three wave sizes (1.5 metres, 3 metres and 5 metres) The project consortium estimates that the converter could produce 200,000 kilowatt-hours a year, which would be enough to supply ten of the households on the island. 'That's not a lot of power, but it is because it is only a small power source,' says Ms Bakke. 'If you integrate the system into a 500-metre breakwater, then you are looking at producing 20 Gigawatt-hours per year.' That would be enough electricity to supply some 4,000 households. In addition to providing cost-efficient energy, the installation of the converter has the advantage that it can be integrated into breakwater infrastructures, thus serving two purposes. '95% of the cost of the demonstrator is for concrete for the breakwater, so building it in a breakwater makes it more competitive,' surmises Ms Bakke. Other advantages listed by the project consortium are the system's high reliability and the fact that it has very few moving parts and can therefore withstand stormy weather conditions. The converter could also be combined with fresh water production mechanisms and hydrogen storage facilities for electricity production during calmer sea periods. However, like with other new energy technologies, such as wind, there are concerns about the impact that such wave energy devices may have on the environment. Noise and changes to marine sediment structure are just some of these concerns. To address this aspect, the consortium will carry out an environmental risk assessment during the course of its work. Ms Bakke believes that that the converter will have a limited impact, similar to that of a normal breakwater, and that noise of turbine will not be sufficiently loud enough to affect marine life. Weather-permitting, it is hoped that the converter and power plant will be up and running by summer 2008. Although the pilot project is to run for another seven years, Ms Bakke is confident that after one year, the project will be ready to provide concrete figures on how much power the converter is capable of producing. The project received €1 million under the 'Sustainable development, global change and ecosystems' thematic area of the Sixth Framework Programme (FP6). The overall cost to develop, build, install and test the system stands at €3.5 million.
Germany, Denmark, Hungary, Norway