Wave energy

Wave-energy studies to date have aimed at producing outline system designs and realistic estimates of their performance and costs. The original devices, which included simple inshore systems, bulky floating `oscillating-water-column/air turbine¿¿ systems and technically complex devices like the duck, have resulted in net generating cost estimates of 10¿¿30p/kWhe, the main differences being in productivity (efficiency) estimates. `Second-generation¿¿ devices are claimed capable of around 6p/kWhe. Generic work has shown that the resource size is less than originally believed. Wave-directional effects, equipment reliability and basic device/converter efficiency lead to a maximum productivity of ~ 25%, say 60¿¿70 TWhe/yr or 10% of UK energy needs. The research does point to ways of improving wave-energy economics. Device efficiency is not an issue, since theoretical considerations have proved that all concepts have equal efficiency potential. Maintenance assessments have shown the importance of using simple systems, like the air turbine. Performance and cost of structures, moorings and power-conversion equipment, benefit from long (spine) structures and are further enhanced by advanced control methods. Improved systems capable of 5¿¿10p/KWh should be possible, but wave energy is unlikely to compete economically with nuclear power.