The evolution of renewable energy technologies may surmount fossil fuel disadvantages. Wave energy is considered one of the best alternatives to fossil energy due to its advantages. The 40-year (1979–2018) spatio-temporal distribution of wave energy is presented using European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) datasets. In addition, the common formula used for wave energy evaluation is derived from the linear wave theory in deep water, which is not applicable in shallow water. Therefore, a new equation that is suitable for both shallow and deep water is derived, which improves the accuracy of the wave energy evaluation for various water depths. The main aim is to investigate the spatio-temporal wave energy for offshore China from 1979 to 2018 and combine the new standard of classification to recommend the optimal area. The nearshore zone from Zhejiang province to Guandong province is considered the ideal zone, and the average annual wave energy density in this area is above 10 kW/m.

To develop novel wave energy conversion devices (WECDs) with excellent performance, the relative wave height and pressure in the chambers of square and curved oscillating water column (OWC) WECDs were compared through physical model tests, and the effects of regular incident wave factors, the opening length, the opening width, and the chamber volume on the aerodynamic performance and wave energy capture efficiency (WECE) of the WECDs were investigated. The results indicated good chamber performance for both the square and curved OWC WECDs. As the incident wave height increased, the wave surface elevation, WECE, and pressure in the chamber all increased, while the relative wave height in the chamber decreased. When the opening length, width, and area of the WECD increased, both the relative wave height and chamber pressure increased. The relative wave height in the chamber increased with decreasing chamber volume; however, the chamber pressure and intrachamber WECE decreased with increasing chamber volume. It is recommended that, in actual engineering applications, the overall efficiency of the device be improved by increasing the opening length, width, area and volume of the air chamber.