Harvesting energy from
electromagnetic waves
A new metasurface will help harvest energy from electromagnetic
waves and could be used as a clean alternative source of power in the future to
help ease the world's energy shortage
For our modern, technologically-advanced
society, in which technology has become the solution to a myriad of challenges,
energy is critical not only for growth but also, more importantly, survival.
The sun is an abundant and practically infinite source of energy, so
researchers around the world are racing to create novel approaches to “harvest“
clean energy from the sun or transfer that energy to other sources.
This week in the journal Applied Physics Let
ters, researchers from the University of Waterloo in Canada report a novel
design for electromagnetic energy harvesting based on the “full absorption
concept.“ This involves the use of metamaterials that can be tailored to
produce media that neither reflects nor transmits any power enabling full
absorption of incident waves at a specific range of frequencies and
polarisations.
“The growing demand for electrical energy around
the globe is the main factor driving our research,“ said Thamer Almoneef, a PhD
student. “More than 80 per cent of our energy today comes from burning fossil
fuels, which is both harmful to our environment and unsustainable as well. In
our group, we're trying to help solve the energy crisis by improving the
efficiency of electromagnetic energy-harvesting systems.“
Since the inception of collecting and harvesting
electromagnetic energy, classical dipole patch antennas have been used. “Now,
our technology introduces `metasurfaces' that are much better energy collectors
than classical antennas,“ explained Omar Ramahi, professor of electrical and computer
engineering.
Metasurfaces are formed by etching the surface
of a material with an elegant pattern of periodic shapes. The particular
dimensions of these patterns and their proximity to each other can be tuned to
provide “near-unity“ energy absorption. This energy is then channeled to a load
through a conducting path that connects the metasurface to a ground plane. The
key significance of the researchers' work is that it demonstrates for the first
time that it's possible to collect essentially all of the electromagnetic
energy that falls onto a surface.
“Conventional antennas can channel
electromagnetic energy to a load but at much lower energy absorption
efficiency levels,“ said Ramahi. “We can also channel the absorbed energy into
a load, rather than having the energy dissipate in the material as was done in
previous works.“
As you can imagine, this work has a broad range
of applications. Among the most important is space solar power, an emerging
critical technology that can significantly help to address energy shortages. It
converts solar rays into microwaves using conventional photovoltaic solar
panels and then beams the microwave's energy to microwave collector farms at
designated locations on Earth. Japan is way out in front of rest of the world
in this realm, with plans to begin harvesting solar power from space by 2030.
“Our research enables significantly higher
energy absorption than classical antennas,“ Ramahi said. “This results in a
significant reduction of the energy harvesting surface footprint.Real estate is
a precious commodity for energy absorption whether it's wind, hydro, solar or
electromagnetic energy.“
Other key applications include “wireless power
transfer directly adaptable to power remote devices such as RFID devices and
tags or even remote devices in general,“ Ramahi noted.
The technology can also be extended to the
infrared and visible spectra. “We've already extended our work into the
infrared frequency regime and we hope to report very soon about near-unity absorption
in those higher-frequency regimes,“ added Ramahi.
MM15APR15
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