Harvard finds new renewable energy source -

Boffins at Harvard have worked out a way of using all that energy that the earth just chucks out into space on a daily basis.

At the moment, the Earth leaks 100 million gigawatts of energy into space where it does not even power a mobile phone.

Now researcher Professor Federico Capasso has worked out a way that you can generate power by emitting, not by absorbing light.

Dubbed an "emissive energy harvester" (EEH) it looks like a solar panel, except instead of catching incoming light, the cell releases infrared radiation to generate energy.

On paper the Harvard team has come up with two kinds of emissive energy harvesters.

Published in the Proceedings of the National Academy of Sciences, the first harvester, a thermal EEH device, consists of a "hot" plate at the temperature of the Earth, with a "cold" plate placed on top.

The cold plate is made of special material that can cool very efficiently by radiating heat to the sky. The heat differences between the plates can generate an average of 2.7 watts per square metr- or roughly .25 watts per square foot. This is extremely low for large-scale power generation.

The other idea which is more promising uses microscopic "rectenna". The antenna emits the Earth's infrared radiation toward the sky. This cools the electrons in the surrounding part of the circuit, forcing a current to flow to the antenna from the warmer diode. This hot/cool flow makes the antenna act as a resistor and produces a voltage.  This imbalance allows the creation of DC power.



The next stage is to develop new types of electronic components that can better generate power at low voltages or boost the overall voltage. However, it could be that this is going to save the world.