Energy and Carbon Audit of an Offshore Wave Energy Converter

The world's first commercial wave farm will feature the 'Pelamis' wave energy converter developed by Ocean Power Delivery. With potential for the manufacture of significant numbers of such devices, there is a need to assess their environmental impact and, in particular, their life cycle energy and carbon dioxide (CO2) performance. The current paper presents an analysis of the life cycle energy use and CO2 emissions associated with the first generation of Pelamis converters. With relatively conservative assumptions, the study shows that at 293 kJ/kWh and 22.8 gCO2/kWh the respective energy and carbon intensities are comparable with large wind turbines and very low relative to fossil-fuelled generation. The energy payback period is approximately 20 months and the CO2 payback is around 13 months. Material use is identified as the primary contributor to the embodied energy and carbon with shipping (including maintenance) accounting for 42 per cent. Improving the Pelamis' environmental performance could be achieved by increasing structural efficiency, partial replacement of the steel structure with alternative materials, particularly concrete, and the use of fuel-efficient shipping.