This study presents a life cycle assessment (LCA) study for a buoy-rope-drum (BRD) wave energy converter (WEC), so as to understand the environmental performance of the BRD WEC by eco-labeling its life cycle stages and processes. The BRD WEC was developed by a research group at Shandong University (Weihai). The WEC consists of three main functional modules including buoy, generator and mooring modules. The designed rated power capacity is 10 kW. The LCA modeling is based on data collected from actual design, prototype manufacturing, installation and onsite sea test. Life cycle inventory (LCI) analysis and life cycle impact analysis (LCIA) were conducted. The analyses show that the most significant environmental impact contributor is identified to be the manufacturing stage of the BRD WEC due to consumption of energy and materials. Potential improvement approaches are proposed in the discussion. The LCI and LCIA assessment results are then benchmarked with results from reported LCA studies of other WECs, tidal energy converters, as well as offshore wind and solar PV systems. This study presents the energy and carbon intensities and paybacks with 387 kJ/kWh, 89 gCO₂/kWh, 26 months and 23 months respectively. The results show that the energy and carbon intensities of the BRD WEC are slightly larger than, however comparable, in comparison with the referenced WECs, tidal, offshore wind and solar PV systems. A sensitivity analysis was carried out by varying the capacity factor from 20–50%. The energy and carbon intensities could reach as much as 968 kJ/kWh and 222 gCO₂/kWh respectively while the capacity factor decreasing to 20%. Limitations for this study and scope of future work are discussed in the conclusion.

Buoy-chain-sprocket wave energy collection device is a new type of oscillating buoy wave energy collection device, which has a good application prospect. The calculation method of the hydrodynamic performance of wave energy device (e.g. the first-level average collection efficiency of wave energy) is the core scientific problem of wave energy device, and it is also the theoretical basis for the optimization and control of wave energy device prototype. In this paper, on basis of linear potential flow theory, after the velocity potentials are calculated with eigenfunction expansion method and matching asymptotic expansion method, the frequency-domain wave loads in the heave, surge and pitch directions of the floating body are obtained. And then the motion coordination relationship of the floating body of buoy-chain-sprocket wave energy collection device is used to establish time-domain hydrodynamic motion response equations of the floating body of the device based on the Cummins method. After these equations are solved via the fourth-order Runge-Kutta method, the first-level average collection efficiency of the wave energy device is acquired. In order to further improve the calculation accuracy, the frequency-domain wave-exciting force is calculated by using variable draft depth when the hydrodynamic response of buoy-chain-sprocket wave energy collection device is calculated in this paper. Finally, the reliability of the above calculation method for the hydrodynamic performance of buoy-chain-sprocket wave energy collection device is verified through physical model experiment.