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Carbon Nanotubes Might Be the Secret Boost Solar Energy Has Been Looking For

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Solar panels are an incredible innovation
in energy tech, but they’re way less efficient than they could be, because they have a problem:
heat. Specifically, waste heat, or energy that’s
lost while converting the sun’s energy into electricity. But a new technology—made possible by carbon
nanotubes—may be just the thing that brings solar panels into the lead for energy technologies. Which would be sweet. In brief, a solar panel works like this: the
solar cell is made of a semiconducting material, like silicon, that’s had some other, differently-charged
elements added to create an internal electric field. When photons from the sun bounce down and
hit the solar panel, they knock electrons off the silicon atoms, and those electrons
can then be pulled into an external circuit as electricity. So there ya go, sunshine into power. But not all of the sun’s rays that touch
a solar panel get turned into electricity, and this is because not all light is created
equal. Electromagnetic radiation, of which visible
light is a part, is a spectrum of many different wavelengths, and only certain-wavelength photons
carry the right amount of energy to knock electrons loose. For the rest of the wavelengths that can’t
displace electrons, that energy is lost, unable to be used in a solar panel to generate electricity. We can actually lose about 70% of the electromagnetic
radiation that hits a solar cell because of this mismatch in energy levels! This is one of the biggest issues facing solar
panel efficiency. And this, paired with other long-standing
problems—like the resistance that electrons face when passing through conducting materials—makes scientists think that in the future, even with improvements to the existing tech, we’re looking at a maximum, peak efficiency of solar panels at 29%. Which still seems pretty low, to be honest. I mean come on, sunlight is free—surely
something can be done about this. Well, one rescuer comes in a surprisingly
tiny package. Researchers at Rice University are adding a film of carbon nanotubes. When looking at why solar panels lose so much
energy, the researchers behind this new tech saw that the radiation from the sun that couldn’t
be absorbed by the solar panels was bouncing off as heat… and they wanted to harness
it. But how to turn that heat into electricity? Thermal radiation, like the kind released by solar cells is broadband— which is kinda messy. Converting sunlight into electricity is only
efficient if the emissions are in a pretty narrow band, nice and precise. So the researchers created wafer-thin films
of carbon nanotubes that can absorb that broadband waste heat and channel it into narrow bandwidth
photons that can be easily converted to electricity. So instead of going from heat to electricity,
the nanotube film makes the conversion process more efficient by taking that energy from
heat to light to electricity. Nanotube film is a perfect material for this
because it can withstand temperatures up to 1,700 degrees Celsius, so it’s not going
to buckle under the heat. And this is huge. It doesn’t require a change to the fundamental
makeup of solar panels, so its minimally disruptive to existing solar infrastructure. And the researchers say that their tech could
theoretically increase the efficiency of solar panels from that measly 29% efficiency maximum….all
the way up to 80%. We live in a world where we’re gravitating
more and more towards renewable energy, and we NEED to. But solar energy, this hugely untapped energetic
resource, currently only produces around 2% of the world’s electricity. Potentially huge leaps in solar panel efficiency
could make so much more of the sun’s energy available for use. The project is still in the prototyping phase
and is a ways out from being used in existing technologies, but if its promises come to
fruition… it could change the way we think about the future of our energy grid, and how efficiently we can power the world with clean energy. Big news. If you want even more on how solar panels
are adapting into the future, check out this video over here on solar cells powered by bacteria. And subscribe to Seeker for energy tech updates as they break. Let us know what other energy developments
you’d like to see us cover down in the comments below and as always, thanks for watching.

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