Apr 1 2020
The electricity that powers appliances and lights homes also generates small magnetic fields that exist everywhere.
A team of scientists has developed a new mechanism to harvest stray magnetic fields all around us and convert the energy into useful, usable electricity. Image Credit: Kai Wang.
Researchers have now designed a novel mechanism that can harvest this wasted magnetic field energy and turn it into sufficient electricity to power advanced sensor networks for factories and smart buildings.
Just like sunlight is a free source of energy we try to harvest, so are magnetic fields. We have this ubiquitous energy present in our homes, office spaces, work spaces and cars. It’s everywhere, and we have an opportunity to harvest this background noise and convert it to useable electricity.
Shashank Priya, Professor, Department of Materials Science and Engineering, Pennsylvania State University
Priya is also an associate vice president for research at Pennsylvania State University (Penn State).
A research team, headed by Penn State scientists, built a device that delivers as high as 400% higher power output when compared to other advanced technology when working with low-level magnetic fields similar to those seen in buildings and homes.
The technology holds major implications for designing smart buildings, which will need self-driven wireless sensor networks to perform things like remote control of systems and tracking energy and operational patterns, the researchers said.
In buildings, it’s known that if you automate a lot of functions, you could actually improve the energy efficiency very significantly. Buildings are one of the largest consumers of electricity in the United States. So even a few percent drop in energy consumption could represent or translate into megawatts of savings. Sensors are what will make it possible to automate these controls, and this technology is a realistic way to power those sensors.
Shashank Priya, Professor, Department of Materials Science and Engineering, Pennsylvania State University
Scientists developed paper-thin devices, measuring approximately 1.5″ in length. These devices can be positioned on or near lights, appliances, or power cords where there are strongest magnetic fields. The magnetic fields rapidly scatter away from the source of flowing electric current, stated the researchers.
When positioned 4″ from a space heater, the device generated sufficient electricity to power 180 LED arrays, and at 8″, it produced sufficient electricity to power a digital alarm clock. The researchers have published the findings in the Energy and Environmental Science journal.
These results provide significant advancements toward sustainable power for integrated sensors and wireless communication systems.
Min Gyu Kang, Study Co-Lead Author and Assistant Research Professor, Pennsylvania State University
The researchers made use of a composite structure, layering a pair of different materials together. One material is magnetostrictive, which turns a magnetic field into stress, and the other is piezoelectric, which changes vibrations, or stress, into an electric field. This combination enables the device to change a magnetic field into electric current.
The device includes a beam-like structure, with one end clamped and the other end free to vibrate in reaction to an applied magnetic field. A magnet placed at the free end of the beam increases the movement and contributes toward more generation of electricity, stated the researchers.
“The beauty of this research is it uses known materials, but designs the architecture for basically maximizing the conversion of the magnetic field into electricity,” Priya added. “This allows for achieving high power density under low amplitude magnetic fields.”
Rammohan Sri Ramdas, an assistant research professor at Penn State, also took part in the research.
The research was also supported by Hyeon Lee and Prashant Kumar, research assistants at Virginia Tech, and Mohan Sanghadasa, a senior research scientist at the Aviation and Missile Center, U.S. Army Combat Capabilities Development Command.
Some of the members in this study were sponsored through the National Science Foundation and the others through the Office of Naval Research.