Turning Walnut Shells into Green Energy

A drop of water, a shell, and a spark of power

University of Waterloo engineers have created a coin-sized device that generates electricity from discarded walnut shells and just a few drops of water.

The “water-induced electric generator” taps into the shell’s natural porous structure, using evaporating water to move charged ions and create usable green energy.

By linking four units, the team powered an LCD calculator, showing potential for small electronics in remote or off-grid settings. Future versions could harvest energy from sweat, rain, or even wood to run sensors, wearables, and emergency devices.

“It all happens with nothing more than a single droplet of water and the shell’s natural architecture, no crushing, soaking or complex processing needed. It’s a simple, yet powerful example of turning waste into clean energy using nature’s own power.”

— Nazmul Hossain, PhD Student

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