Harvesting the Earth's infrared energy

Steve Byrnes and colleagues at Harvard University suggested harvesting some of the 10¹⁷ W of infrared thermal radiation emitted by the Earth into outer space as a result of the warmth it receives from the Sun. The process is called "emissive energy harvester" (EEH). The team envisages that such a thermal EEH device would consist of a "hot" plate at the temperature of the Earth and air, with a "cold" plate on top made from a very emissive material that is cooled by radiating heat to the sky. The surface of the Earth, at a temperature of about 275–300 K, is much warmer than the 3 K of outer space.
Year-round, the devices would produce an average of 2.7 W/m², or 0.06 kWh/m² per day, the researchers calculated. "We have found that infrared emissions can generate a substantial amount of energy, during both day and night," says Byrnes. 
Read more here: http://physicsworld.com/cws/article/news/2014/mar/14/harvesting-the-earths-infrared-energy
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