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Curated by RSF Research Staff

Quantum Tunneling used to Harvest Electricity from the Earths Heat

It is now common place to use solar panels to convert solar rays into electricity - but what about all the other rays that are absorbed by the Earth’s surface?

Sunlight is absorbed by the Earth’s surface, its oceans and atmosphere and is continuously re-emitted as infrared radiation - so why isn’t this energy utilized as electricity? Solar panels work via the photoelectric effect, or more specifically the photovoltaic effect, where light incident upon a metal results in the emission of electrons which are excited to move as charge through the metal. The amount of charge – electric current - that can be generated depends on the wavelength of the photons and the threshold wavelength of the metal. Sunlight is predominately in the visible and infrared wavelengths and a small amount of UV, so most solar panels work in the visible range as that is more efficient, although the latest developments are utilizing full-spectrum photovoltaic material.

Another way to tap into these infrared waves is in the same way you would tap into radio waves and micro waves – with an antenna. However infrared waves are much shorter than micro and radio waves so require nano scale antennas. As well the diodes - required to convert the alternating signal to direct current charge for batteries or other power devices – do not operate at the high frequencies of infrared rays. A team at KAUST now believe they have overcome this with the help of quantum tunneling – the quantum property of borrowing energy (read more here). They achieve this by utilizing a unique bowtie-shaped nano-antenna and a metal-insulator-metal (MIM) diode.

If such devices prove efficient, it could have huge implications for electricity generation around the world.



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