A Canadian research team has managed to turn discarded walnut shells and a simple drop of water into enough energy to power an LCD calculator.
The device, named WEG (Water-Evaporated Generator), represents a low-cost and highly sustainable solution to supply small electronic devices in remote areas or without access to the electrical grid.
## How does the WEG work: natural architecture at the service of energy
The generator takes advantage of the internal microstructure of the walnut shell, which contains a network of porous channels designed by nature to transport water and nutrients. By depositing a drop of water, it evaporates and circulates through the pores, mobilizing electrically charged ions.
When interacting with the surface, a charge imbalance occurs that generates electricity, captured by two electrodes.
“Everything happens with nothing more than a drop of water and the natural architecture of the shell, without the need for crushing, soaking, or complex processes,” explained Nazmul Hossain, the project leader and a doctoral candidate in mechanical and mechatronic engineering.
## From hazelnut to common walnut: selecting biomaterials for energy efficiency
The inspiration came from observing the internal structure of a hazelnut shell with an electron microscope. After trials with different nuts, it was concluded that the common walnut offered the greatest energy potential.
To improve performance, the shells were cleaned, treated, polished, and precisely cut, and integrated into a 3D-printed casing.
By connecting four WEG units, the system managed to power a calculator, demonstrating its viability as a portable energy source.
## Educational and circular bioenergy: the value of agricultural waste
Nut shells are abundant agricultural waste, with low moisture content and high availability in countries like the United States, Spain, and Iran.
Their use as raw material for bioenergy does not interfere with food production and allows for waste reduction while exploring sustainable energy alternatives.
This approach also has educational potential: it integrates chemistry, physics, and environmental sciences in school and university projects, as demonstrated in a study published in Science in School, where European students conducted experiments with burnt shells to release energy.
## Future applications: sensors, health, and disaster relief
Potential applications of the WEG include environmental sensors for forest monitoring, portable health devices, and emergency equipment in areas without electricity. The operating principle allows the generator to use ambient moisture, rain, or human perspiration as an energy source.
Currently, the team is working on portable versions of the device and on new sustainable materials, such as wood, to expand the range of options.
## Accessible technology for a just energy transition
The project was published in Energy & Environmental Materials and opens up new possibilities for decentralized electrification.
Led by Nazmul Hossain and supervised by professors Norman Zhou and Aiping Yu, the project demonstrates that it is possible to power electronic devices with natural materials and available resources, without depending on conventional infrastructure.
This innovation aligns with the global challenge of advancing towards more sustainable energy matrices, making the most of agricultural waste, and promoting an inclusive and decentralized energy transition.
