To Investigate and Characterise the Wave Energy Resource surrounding Guernsey Island with a particular focus on the Western side

This report was commissioned by the States of Guernsey, Commerce and Employment, Renewable Energy Team (RET) - in conjunction with Plymouth University - to investigate the electricity generation potential of ocean wave energy resources located within their jurisdictional waters. The intent is to provide the Renewable Energy Team and other policy making bodies with objective and quantitative information upon which to make informed decisions regarding the future development of the state’s wave energy resources. This study focuses on the assessment the wave resource surrounding the island, but with a particular focus on the West coast. Further investigation is carried out at three separate locations to identify the potential contribution to Guernsey Electricity from installed Wave Energy Convertors (WECs). Ocean wave energy is one of the most concentrated and widely available forms of renewable energy in coastal areas. The worldwide wave energy resource potential is estimated at 8,000 - 80,000TWh/yr. This compared against current worldwide electric consumption of 132,000 TWh/yr, would see that a significant portion of the planets needs could perhaps be achieved through wave energy. Furthermore it is estimated that 40% of the world’s population live within 100km of the coast. This, establishes a strong relationship between resource and demand. As security of supply and population increase becomes more of an issue in future years, this may allow for a widespread adoption of emerging technologies that generate electricity from ocean waves. Driven by the fact that in isolated island environments, like that of Guernsey, the extraction of renewable energy is becoming an increasing issue as electricity prices intensify. The objective of this report is to gauge the wave energy potential for Guernsey’s waters. Wave power, though relatively predictable in the waters surrounding Guernsey has one main disadvantage - variability. Great variations in power levels between wave to wave, from day to day and even month to month can provide uncertainty to an investor or governing body seeking deployment of wave energy convertors. In this report the principles of wave resource characterisation are addressed, and will set the foundation for future wave development projects in the area. These principles are independent of the scale of the device deployment project. Guernsey’s wave resource is concentrated off the West coast. Small scale installations, such as the OWC Pico power plant, in the Azores, are an exciting prospect for small island communities, which are presently disadvantaged by relatively expensive power supply within the large regions. In order to provide an accurate assessment of the resource but also to study the variability between days, months and even years, longer data sets are required in order to provide these reliable wave climate statistics, thus the aim of this report. With significant wave heights peaking in winter months of 6.7 meters and summer month’s minimal value of 0.25 meters, high level analysis of the available resource is key. The model computations for Guernsey’s waters achieved excellent correlation when compared against Met office UK WaveWatch III data. With no validation data available in shallow waters (less than 40 meters), through wave buoys or freely available sources, the deep water validation location serves as a relatively true representation of the wave climate off Guernsey Island. Here the ratio of water depth to wavelength (h/λ) is greater than 0.5. All power estimates are assumed to have no intermediate or shallow water effects on wave energy. Finally the model was used to create power density maps and select sites which contained the most energy. These locations where then investigated to identify their extractable energy potential. Using two different devices, 8 Wave dragon energy convertors yielded 3.2% of the islands total energy consumption, over the two years investigated. A total of 12 Pelamis P1 devices yielded 0.88% over the same period. Figures are based on a total Island consumption of 400,000MW/h a year