Towards Blue Energy: The Design, Dynamics, and Control of an Innovative Power Take Off for Ocean Wave Energy Harvesting

The ocean wave energy potential along US coastline is 64% of the electricity generated from all sources in the US. Over 53% of the population live with 50 miles off the coasts, so ocean waves offer ready opportunity to provide electricity without long-distance electricity transmission. However, the ocean wave energy harvesting is still in its infant stage worldwide. The power takeoff (PTO), the machinery to convert the mechanical energy into electricity, is widely considered as the single most important element in wave energy technology, and underlies many of the failures to date (A. Falcao 2010). Revolutionary power takeoff beyond the direct and indirect drives is urgently needed in order to realize the vast blue energy potential from the ocean. This talk will present the design, dynamics modelling, power electronics control, lab test, wave tank test, and ocean trial of a mechanical motion rectifier based power takeoff, which converts the irregular oscillatory wave motion into regular unidirectional rotation of the generator. Lab tests show that up to 80% mechanical energy conversion efficiency was achieved with reduced force in the PTO motion system. The rotatory inertia and two-body system design can further increase the power output in a large frequency range. Wave tank test and ocean trail also validated the high efficiency and reliability. Please click Additional Files below to see the full abstract