Sun's heat to power green buildings

The Sun's light can be readily converted into electricity by solar cells, but a practical way to tap directly into the heat generated by sunlight to mass produce electricity is yet to be developed.

A team of researchers from the Integrated Nanotechnology Lab at King Abdullah University of Science and Technology (KAUST) in Thuwal, Saudi Arabia, have embedded nano-pellets of a commercially available thermoelectric material, which can generate electricity when there is a different temperature on each side, into 5 mm holes bored into window glass. Cooper wires connect the pellets to form thermoelectric grid.

The design generated 304 watts of electricity from a 9 m2 glass window at a temperature gradient of 20°C. "This is a pretty reasonable number to power up a small room of 100 square feet with common appliances, [bare] any heat induction appliances" says Muhammad Hussain, the lead author of the study, published in Scientific Reports.

High electrical resistance in the copper wires was the main limiting factor. The researchers suggest this can be improved by finding alternative ways to connect the thermoelectric pellets.

Power could be generated in off-peak hours, or when the inside was not air-conditioned, as long as there is a good temperature gradient between outside and inside. The researchers contend this makes thermal solar energy a reliable complimentary source of electrical power.

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