Development of a novel wave energy converter based on hydrodynamic lift forces

Oceans represent a significant, predictable resource for renewable energy. The main forms of ocean energy are waves, tides, marine currents, salinity gradient and temperature gradient. While wave and tidal energy are the most mature technologies, the commercially viable extraction of energy from ocean waves has yet to be achieved. The EU-funded LiftWEC project focuses on the development of LiftWEC, a novel type of wave energy converter. Specifically, it will develop a new concept based on the exploitation of lift forces generated by wave-induced water velocities. Current concepts need to couple through diffraction or buoyancy forces, but this new approach will use lift forces (as opposed to the traditional buoyancy). In addition, the LiftWEC concept has the advantage that the motion can be unidirectional, which significantly simplifies the extraction of energy.

This proposal is for the development of a novel wave energy converter whose primary coupling with the waves is through hydrodynamic lift forces. The objective is to determine the potential of this concept to produce renewable energy at a commercially competitive price whilst ensuring a minimal environmental/social impact. This will be achieved by a combination of numerical/physical modelling and desk-based studies of the structural design, the operational & maintenance requirements and the environmental/social impacts of the technology. The numerical/physical modelling will demonstrate the concept’s performance, thereby taking the concept to TRL4, whilst the desk-based studies will allow the socially-acceptable commercial potential to be determined. Wave energy is one of the few untapped sources of renewable energy that could make a significant contribution to the future energy system. However, a study of the literature and a patent search indicates that of the hundreds of concepts that have been developed only four couple to the waves through lift forces, whilst the rest couple through diffraction or buoyancy forces. However, coupling through lift forces has the significant advantage of reducing extreme loads (by reducing the circulation like a wind turbine) which facilitates survivability, and produces unidirectional rotation, which simplifies power extraction. Unfortunately, none of the current lift-based ave energy concepts have a high efficiency in all sea-states due to difficulties in maintaining a good lift-to-drag ratio. The novel ideas in this proposal are designed to achieve this and thus enable the commercial development of wave energy and the acceleration of clean energy solutions.