Flexible Responsive Systems in Wave Energy

Abstract

Wave energy convertors (WECs) offer opportunities for off-grid and grid-scale applications but are expensive compared with other renewable energy options. WEC systems that exploit novel use of flexibility, including deformable materials, may offer improved performance, survivability, reliability, and reduced cost compared with steel or concrete alternatives. In this work, origami theory is used to optimise a flexible WEC design that connects flaps with origami pleats and functions like a bellow. The approach minimizes strain energy through rigid-foldable mechanisms, enabling folding motion to occur via rotational hinges and preserving the rigidity of panel facets. By means of a mathematical model, we determine the performance of such a device as a wave energy converter. Materials available for use in flexible deformable systems are assessed by considering their performance in fatigue under repeated loading cycles and in the marine environment. We comment on likely challenges in manufacturing suitable materials at scale.  Fundamental hydrodynamics experiments provide insight into the wave-structure interaction of elastomer materials. Numerical modelling capability for such applications is investigated. Scale models of the origami-inspired flexible WEC concept are designed and tested in the COAST Laboratory at 1:160 and 1:50 scale. The 1:160 model is a fully enclosed origami-inspired WEC with orifice plate to represent the Power Take-Off (PTO) system; the 1:50 scale model incorporates a series of servo motors to replicate PTO forces on each flap.  Results comparing the capture widths achieved for linear, rotational, and pneumatic PTO types are presented for representative sea states. It is found that the linear PTO was the most suitable for the cases considered.