Imagine powering a calculator or a small electronic device using nothing more than waste nut shells and a single drop of water.
That is exactly what researchers at the University of Waterloo in Canada have achieved.
Their innovative device, about the size of a coin, could open the door to clean, inexpensive, and sustainable energy solutions for the future.
The device is called a water-induced electric generator, or WEG. It works by using the natural structure of walnut shells, which are full of tiny, interconnected pores.
When a drop of water evaporates from these pores, it sets off a fascinating chain reaction.
The moving water carries electrically charged particles, known as ions, through the pores. These ions interact with the surfaces inside the shell, creating a charge imbalance. That imbalance can then be captured and used as electricity.
The idea for the device came from an ordinary snack.
Nazmul Hossain, a Ph.D. student in mechanical and mechatronics engineering at Waterloo, ate a hazelnut one day and decided to look closely at its shell under an electron microscope.
What he saw was striking: a natural, highly complex system of channels and pores designed to transport water and nutrients. To Hossain, it looked like the perfect architecture for harvesting energy.
His team tested four different kinds of nut shells and found that walnuts performed the best at generating electricity.
They then carefully prepared the shells—cleaning, polishing, and shaping them—before adding electrodes, wires, water droplets, and a 3D-printed case to complete the device.
Each single WEG unit produces a small amount of power, but when four were connected together, they generated enough electricity to run an LCD calculator.
While that may not sound like much compared to a power plant, the implications are exciting.
This technology could one day power sensors, wearable health monitors, or small communication devices in remote areas where traditional batteries or electricity are hard to access.
“This is a simple but powerful example of turning waste into green energy using nature’s own design,” said Hossain.
“Imagine devices monitoring forests for environmental changes, or disaster-relief tools operating off nothing more than tiny droplets of water from the air.”
The Waterloo team is already looking ahead to new uses. They are experimenting with wearable WEGs that could collect energy from sweat or rain, and they are exploring whether other natural materials, such as wood, could replace nut shells.
If successful, this approach could offer a low-cost, eco-friendly alternative to batteries and help expand access to clean energy across the globe.
