“This weekend, dear, shall we clean out the basement or go solar?” This scenario may soon be a real possibility, using a back-to-the-future approach called thermoelectric paint.
Despite their many benefits, solar photovoltaic panels are not a do-it-yourself delight. Installing them is complex and typically requires someone certified to do it. They’re expensive too, and with payback times of 10 years or more, they require a real commitment.
Now imagine a home energy system that, like solar PVs, harnessed the sun’s power – but was something you could easily do yourself. This is the promise of thermoelectricity.
Thermoelectric materials have a cold side and a warm side. The warm side releases charge, which flows to the cold side, at which point you have a separation of positive and negative charge and, hey presto, electricity!
In the 1950s, solar pioneer Maria Telkes used thermoelectric materials to generate a very modest flow of electricity. But the cost of the material and the inefficiency of the process made silicon solar panels considerably more cost effective. Solar thermoelectric landed in the technology junk heap, and remained there for decades.
Recently, researchers began investigating if thermoelectric materials might offer a way around a fundamental constraint on solar PV development. Because PVs can make use of only a relatively narrow range of the light spectrum, their efficiency is limited: the best commercial models currently available have a maximum of around 20%. Since thermoelectric materials have the potential to make use of a much broader range of the spectrum, they can potentially beat solar photovoltaics on price and performance – even with inferior efficiency.
Professor Charles Stafford, a theoretical physicist at the University of Arizona, recently published a paper arguing that thermoelectric paint could provide an affordable, consumer-friendly path to solar energy usage. “Our calculations show that quantum effects should lead to very large thermoelectric voltages in these materials. And if the materials are cheap enough, we don’t need to worry that much about efficiency”, he says. He has identified a type of polymer called polyphenyl ethers that might do the trick.
How far down the road toward commercialisation are we? Not very. “I’m a theoretical physicist”, Stafford points out. Still, while noting that “the devil is in the details”, he does not “foresee anything that will block it. With the right push, thermoelectric paint could be on the market five years from now.”
Which means we could all soon be up on the rooftops, rolling out solar.