Abstract
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). The state‐of‐the‐art ocean wave energy technology either uses directdrive power takeoffs with linear electromagnetic generator or indirect‐drive power takeoffs using intermediate fluid. The direct drives are simple and reliable but require heavy and bulk permanent magnets; the indirect drives are more compact but suffer from serious shortcomings on the complexity, reliability, and efficiency. Revolutionary power takeoff is urgently needed in order to realize the vast electricity potential from the ocean waves. This talk will present the design, modelling, 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 rotation 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. The mechanical motion rectifier based power takeoff can be integrated into the point absorbers, wave attenuators, wave terminators, or other type of wave energy converter whenever oscillatory wave motion is involved. New extension has been made to simultaneously convert both ocean wave and marine current energy using a single power takeoff device.