The Influence of Sizing of Wave Energy Converters on the Techno-Economic Performance

Abstract

Currently, the techno-economic performance of Wave Energy Converters (WECs) is not competitive with other renewable technologies. Size optimization could make a difference. However, the impact of sizing on the techno-economic performance of WECs still remains unclear, especially when sizing of the buoy and Power Take-Off (PTO) are considered collectively. In this paper, an optimization method for the buoy and PTO sizing is proposed for a generic heaving point absorber to reduce the Levelized Cost Of Energy (LCOE). Frequency domain modeling is used to calculate the power absorption of WECs with different buoy and PTO sizes. Force constraints are used to represent the effects of PTO sizing on the absorbed power, in which the passive and reactive control strategy are considered, respectively. A preliminary economic model is established to calculate the cost of WECs. The proposed method is implemented for three realistic sea sites, and the dependence of the optimal size of WECs on wave resources and control strategies is analyzed. The results show that PTO sizing has a limited effect on the buoy size determination, while it can reduce the LCOE by 24% to 31%. Besides, the higher mean wave power density of wave resources does not necessarily correspond to the larger optimal buoy or PTO sizes, but it contributes to the lower LCOE. In addition, the optimal PTO force limit converges at around 0.4 to 0.5 times the maximum required PTO force for the corresponding sea sites. Compared with other methods, this proposed method shows a better potential in sizing and reducing LCOE.

Wave Energy Converter’s Slack and Stiff Connection: Study of Absorbed Power in Irregular Waves

“…Large buoys for small generators may not lead to extensive energy absorption. Therefore, the buoy size optimization should be carried out together with PTO-size optimization as in [51]. Moreover, from an economic view, the material costs for the large buoys may not be worth the investment.…”

The Influence of Linear Permanent Magnet Generator Sizing on the Techno-Economic Performance of a Wave Energy Converter

“…In order to obtain Fe and Fr, the excitation force, hydrodynamic damping and added mass coefficients are necessary. They are calculated by open source boundary element method (BEM) software Nemoh, and the results have been reported in [3]. Besides, the optimal PTO damping coefficient for each wave state and the given force and displacement constraints can be obtained by the method proposed in [3].…”

“…As the PTO damping coefficient is determined by the method proposed in [3], the required generator force can be calculated by (2). Then, the power taken by the generator windings is calculated as…”

“…However, the techno-economic indicators of WECs, such as their LCOE, are not competitive with other renewable technologies [2]. Our current work presents a collective sizing method for WECs, by which a heaving point absorber and PTO sizing can be implemented to reduce the LCOE [3]. It came to a conclusion that downsizing the PTO system was beneficial for reducing the system LCOE.…”

“…On the other hand, for the linear PM generators, the PTO sizing also has an influence on their conversion efficiencies [11]. This last aspect has not yet been considered in our recent paper [3] where the PTO efficiency was assumed to be constant regardless of its size.…”