Harnessing waves with folds: a flexible origami-inspired wave energy converter

• Enclosed origami-inspired wave energy converter (WEC) that achieves volume change. • WEC design uses folding, not stretching, to minimise strain and energy consumption. • The design places power take-off above sea level to improve sealing reliability. • Finite element analysis and downscaled prototype indicate low strain, long fatigue life, and resilience to irregular waves and misalignment. Ocean waves offer sustainable power yet the design of efficient and durable wave energy converters (WECs) remains challenging. We focus on a WEC that harvests energy from chamber volume change as two bottom-hinged plates open and close with passing wave troughs and crests, driving a turbine generator. For the first time, we present an origami-inspired enclosed WEC whose plates are linked by rigid pleats and confined membrane regions. Unlike traditional flexible WECs that connect the flaps with elastic membranes that stretch, our design achieves predictable cyclic motion through origami folding mechanisms. Using an analytical design method, we optimize dimensions of the pleats and membranes that keep membrane strain minimal during operation. The analytical design is confirmed by finite element analyses, which indicates negligible membrane strain under normal operation, therefore long fatigue life. Tests on a 1:160 scale prototype achieve a capture width ratio of 0.35 and demonstrate robustness under irregular waves and deliberate misalignment. Our WEC design allows the power take-off (PTO) system to be positioned above sea level, ensuring the PTO system operates in air and remains unaffected even if sealing fails. These results demonstrate the potential of origami-inspired WECs as viable and scalable approaches to wave energy harvesting.