Environment |


Nature-powered innovation


Inspired by the elegant motion of fish tails, EEL Energy is redefining renewable energy with biomimetic hydrokinetic generators – bolstered by advanced carbon composites from Exel Composites to withstand the extreme demands of underwater environments


SPECIALISING IN HYDROKINETIC MACHINES, EEL Energy’s patented undulating membrane draws inspiration from the movements of fish tails. This biomimetic design captures kinetic energy from water currents, providing a sustainable method for generating electricity that is efficient and non- disruptive to aquatic ecosystems The undulating membrane traces its origins to


Above: Xavier Peroutka, CEO, EEL Energy


groundbreaking research in the medical field by Jean-Baptiste Drevet in 1996. He leveraged a polymer membrane that mimicked the undulating movement of marine animals to propel fluids, functioning as a pump that creates flow similar to the human heart. This technology has proven effective in medical devices and is adaptable for use in renewable energy generation. The vortices created by turbulent flow in water can be captured by a flexible membrane and the undulating motion used to drive an electrical generator “Our membrane used to be made up of a semi-rigid


structure covered in a rubber layer,” explained Xavier Peroutka, CEO at EEL. “The rubber acted as a sail, capturing the pressure from the water’s current and transmitting it to the membrane’s skeleton. As the membrane deformed, strain energy was generated and transformed into electricity through electromagnetic converters positioned on the membrane. “Coils of wire placed within the structure moved relative


to magnets embedded in the system during deformation. This movement induces an electrical current through electromagnetic induction, converting the membrane’s mechanical energy into electrical energy.” However, as EEL embarks on bringing hydrokinetic


Below: EEL’s hydrokinetic generator in use, with the undulating membrane below the surface of the water


energy production to market, it faces significant challenges. The underwater environment is particularly demanding, necessitating materials that can withstand extreme stress and pressure. “Hydrokinetic generation exerts up to 30 times


more mechanical stress on equipment than wind energy production,” explained Peroutka. “Despite the challenges, it’s worth persevering. Whilst a wave power generator relies on intermittent wave action and solar and wind depend on favorable weather conditions Hydrokinetic generators can produce energy constantly throughout their life by leveraging the water currents in rivers or tidal flow. The predictability of hydrokinetic energy generation is needed by communities across the globe in a green revolution that threatens to leave the neediest behind.”


Seeking material expertise To address the challenge, EEL sought out Exel


Composites, a leader in advanced pultruded and pull- 36 | August 2025 | www.waterpowermagazine.com


wound composite materials. The collaboration aimed to enhance the resilience of EEL’s membrane and refine its performance for harsh underwater conditions. EEL and Exel Composites initially crossed paths at the JEC exhibition in 2021. For EEL, this was more than just an opportunity to display its hydrokinetic technology; it was a critical step in overcoming its greatest challenge. The underwater environment places significant demands on the membrane system, and EEL was eager to find robust materials that could withstand these extreme conditions. Initially, EEL reinforced its membrane with


fiberglass, but this original design revealed a critical flaw: delamination. Under the harsh cyclic loading of the underwater conditions, the membrane underwent large deformations, inducing high strains in the structure. The strain caused the layers of the membrane to separate, allowing water to infiltrate and compromise its functionality.


Recognizing the serious implications of this issue


– where a failure of the membrane during operation could jeopardize the entire hydrokinetic system – EEL sought the expertise of a materials specialist to develop a solution capable of withstanding the continuous mechanical stress required for effective operation. For Exel, this challenge illustrated the complexity


of creating a solution that was both durable, while balancing flexibility and resilience. The quest for a material that could endure the rigors of underwater energy generation became the focal point of their collaboration. Interestingly, the solution didn’t require inventing something new. Rather, it resided in a proven material already designed to withstand the rigors of renewable energy production. One that can resist bending without breaking under the demands of the environment.


From the sky to the sea: wind blades


in action “The key to our successful collaboration was recognizing that our carbon fiber flats, originally designed for wind turbine blades, could be repurposed for EEL’s hydrokinetic membranes,” explained Neil Dykes, research and development manager at Exel Composites. “These flats provide the stiffness and strength required to withstand harsh wind conditions, making them ideal for this application.” Exel used multiple layers of discrete carbon flat


profiles, the same as those developed for wind turbine applications. These carbon fiber flats are stacked to create beams which were strategically integrated into the membrane. Three bars were placed across it at 50,


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