New solar energy technology doubles efficiency. Makes electricity from light and heat.

August 2, 9:15 PMAlbuquerque Science ExaminerAaron Cowan

A new solar energy capture technology is able to generate electricity from light and heat at the same time, producing double the efficiency of existing solar panels, according to new reports on August 2, 2010. Current solar panels, called photovoltaic cells, become less efficient as heat increases, whereas this new technique becomes more efficient as it gets hotter.

This new technique uses a principle called photon enhanced thermionic emissions or PETE, in which solar energy is concentrated on a semiconductor receiver coated with cesium metal. While normal photovoltaic materials would have problems performing even at 100 degrees Celsius, PETE operates all the way up to 800 degrees C, which are the types of temperatures usually attained by a parabolic dish or trough solar concentrator.

Solid-state thermoelectric generators which are semiconductors that produce electricity directly from heat have been in use for some time. However, they do not produce electricity from visible light and are usually limited to somewhere between 5 and 10% efficiency. Furthermore, thermoelectric generators often require extremely high temperatures to generate electricity at all.

Devices based upon PETE would be able to generate substantial amounts of electricity even at 200 C.

Sandia National Laboratories, in Albuquerque, New Mexico has done considerable work with solar thermal concentration via parabolic reflectors, and heat pipes at their National Solar Thermal Test Facility, and as devices based upon PETE are refined, it is likely they will be tested at locations such as this.

After all, the solar energy in a 100 square mile area of the US could provide all of its electricity needs. Therefore, if technologies like PETE can boost efficiency, solar may finally be able to become cost competitive with fossil fuel based energy resources.