Air EnergyFriday 8th November 2013
There seems to be an increasing number of research projects and developments looking at harvesting energy from various sources. Research at Duke University in the U.S. has looked at using inexpensive materials configured and tuned to capture microwave signals.
The researchers at the university’s Pratt School of Engineering have designed the power-harvesting device which matches the efficiency of modern solar panels. Their device wirelessly converts the microwave signal to direct current voltage capable of recharging a cell phone battery or other small electronic device.
It operates in a similar way to solar panels, which convert light energy into electrical current, with this device tuned to harvest the signal from energy sources such as satellite signals, sound signals or Wi-Fi signals.
The device has metamaterials, structures that can capture various forms of wave energy and then tunes them for useful applications.
Potentially this metamaterial coating could be applied to the ceiling of a room, as an example, to redirect and recover a Wi-Fi signal that would otherwise be lost. Another application could be to improve the energy efficiency of appliances by wirelessly recovering power that is now lost during use - magic!
Undergraduate engineering student Allen Hawkes, working with graduate student Alexander Katko and lead investigator Steven Cummer, professor of electrical and computer engineering, used a series of five fiberglass and copper energy conductors wired together on a circuit board to convert microwaves into 7.3V of electrical energy.
“We were aiming for the highest energy efficiency we could achieve,” said Hawkes. “We had been getting energy efficiency around 6 to 10 percent, but with this design we were able to dramatically improve energy conversion to 37 percent, which is comparable to what is achieved in solar cells.”
“It’s possible to use this design for a lot of different frequencies and types of energy, including vibration and sound energy harvesting,” Katko said. “Until now, a lot of work with metamaterials has been theoretical. We are showing that with a little work, these materials can be useful for consumer applications.”
The researchers reckon that further development could see the metamaterial built into a cell phone, recharging wirelessly while not in use.
The potential uses, with combination of devices, could allow power to become accessible almost anywhere, as long as it can tune in signals from Wi-Fi or satellites or similar.
Source: Duke University
Friday 8th November 2013