A generator made from recycled cigarette butts, wild sugarcane, and used batteries was able to produce up to 1.16 volts of electrical voltage using only moisture from the air. According to the developers, this technology could become an inexpensive power source for sensors, wearable electronics, and other low-power devices.
The development was presented by scientists from the BGMEA University of Fashion & Technology in Bangladesh, the University of Manchester in the United Kingdom, and the Central Queensland University in Australia.
The idea of generating electricity from air humidity is not new, but most such devices are either made from expensive materials or produce voltages too low for practical application. The researchers addressed this problem by developing a multilayer composite that efficiently absorbs moisture, converts it into an ionic solution, and directs the movement of charged particles.
The device is based on two layers of wild sugarcane fibers, between which a lattice of purified cigarette filter fibers is placed. Ordinary table salt was added to the material. On one side, a paste of carbon and manganese dioxide extracted from used batteries was applied; on the other, aluminum foil also obtained from electronic waste was placed.
When the material absorbs moisture from the air, the salt dissolves in a microscopic water film and dissociates into positively and negatively charged ions. Due to the moisture gradient within the composite, the ions begin to migrate, creating an electric field and a potential difference between the electrodes. The carbon layer accumulates charge, while manganese dioxide helps maintain voltage for longer periods. Unlike a battery, this generator does not store energy but produces it only during moisture absorption from the surrounding air.
One such generator, roughly the size of a postage stamp, provided a voltage of up to 1.16 V at a relative humidity of about 65% and a power density of up to 16.44 microwatt per cubic centimeter. When several elements were connected, their output increased The four generators, operated sequentially, produced 1.79 volts and a maximum current of 323 microwatts, which was adequate for the sustained operation of a small LED lamp continuously for more than three hours without using capacitors or other energy storage devices.
The researchers also demonstrated that the device operates cyclically. As the material dries, the voltage gradually decreases; however, after reabsorbing moisture, electricity generation is fully restored. Tests lasting nine days confirmed that the device responds stably to natural changes in ambient humidity and temperature.
According to the scientists, the device under development is not yet capable of replacing conventional batteries, but it could become an inexpensive power source for autonomous sensors, smart clothing, and other low-power electronics. An additional advantage of the technology is that almost all of its components are made from waste materials such as invasive plants, cigarette butts, and used batteries, which would otherwise end up in landfills.
