The cold of the universe generates power
When Earth’s heat rises towards the freezing cold of space, it brings energy. Electrons lose energy as infrared radiation from the top of the inverted solar cell, causing a voltage difference that causes electricity to flow through a circuit.
Heat speeds up electrons
1 At room temperature, electrons speed about in random directions in a material consisting of mercury, cadmium and tellurium. This material was chosen because it can convert infrared radiation into energy no matter whether it receives or emits radiation. As all electrons move at the same speed, the charge is the same throughout the material.
Cold slows down electrons
2 When the warm material of the solar cell is subjected to the cold of space at night, the material emits heat radiation in the form of infrared photons. Each photon carries energy away from the material, and as the energy is removed from the electrons, these slow down in the upper part of the solar cell that faces space.
Voltage generates power
3 The difference between the number of fast electrons at the top and bottom causes a voltage difference, as more electrons move about freely at the bottom. The voltage difference forces power around a circuit, because the electrons flow from the negatively- charged end to the positivelycharged end to offset the imbalance.