Is this breakthrough a completely new path to solar efficiency? Maybe so. And if so, this news sounds very promising.
Two things have to happen before solar is truly economically viable: costs must come down quite a bit, and the efficiency has to at least be within spitting distance of petroleum and other traditional natural resources. Photon enhanced thermionic emission (PETE) sounds like very good news on the efficiency front. It might even offer some cost benefits as well.
The basic concept behind this process announced by Stanford University engineers is to coat a piece of semiconducting material with a thin layer of caesium making the material capable of using both light and heat to generate electricity. This is a substantial upgrade over photovoltaic technology – the current standard for solar panels – because while photovoltaics become less efficient as they heat up, the PETE process operates best at high temperature. How high? PETE’s peak efficiency doesn’t hit until it reaches over 392 degrees Fahrenheit (200 degrees Celsius). With that in mind, PETE is most efficiently deployed in solar concentrators, such as parabolic dishes, in large-scale installations.
The upside is a solar energy process that could make power production twice as efficient as current solar technology and it might even compete with petroleum on a cost basis.
Nick Melosh, assistant professor of materials science and engineering, and leader of the Stanford research group says: “This is really a conceptual breakthrough, a new energy conversion process, not just a new material or a slightly different tweak. It is actually something fundamentally different about how you can harvest energy.”
He adds, “The PETE process could really give the feasibility of solar power a big boost. Even if we don’t achieve perfect efficiency, let’s say we give a 10 percent boost to the efficiency of solar conversion, going from 20 percent efficiency to 30 percent, that is still a 50 percent increase overall.”
One more advantage of the PETE process is the materials going in are inexpensive and readily available, meeting criteria number one – lower cost – of the solar energy mantra.