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Creating a new field of science is an impressive starting point for a new technology. But no matter how good the beginning, turning a scientific breakthrough into a saleable product is a tough way to make money.
MTPV, a US company specialising in energy generation from thermal photovoltaics, is in the business of doing just that. Armed with a fundamental patent governing a new area of physics known as the “near field”, the company could not have asked for a better head start.
A decade later, the company is only now close to a product on which it can make money by exploiting industrial waste heat.
“Having created this area of science, it is relatively obvious if someone is infringing on our fundamental patent,” says David Mather, MTPV managing partner and founder, “as the performance would go beyond the laws of physics. But getting our intellectual property recognised and enforced is expensive.”
So how does MTPV’s technology work? Thermal photovoltaic (TPV) energy takes the concept of a photovoltaic cell – using the photons from light to generate electricity as in a solar panel. But instead of using the sun as the source of photons, it uses heat to light up a material on one side of a chip which then provides the photons for the PV cell that forms the second layer of the chip.
The concept is not new. However, until 1998, it was thought to be limited by Planck’s law, which governs the intensity of energy that radiates from a heated body. The problem with thermal photovoltaics – indeed with photovoltaics in general – is efficiency. To generate enough electricity, either the size/number of the cells has to be huge or the heat astronomical.
The breakthrough upon which MTPVs technology is based – the “near field” – came by exploring a caveat noted by Max Planck himself. He said his theory held true only when the gap between the heated body and the body trying to capture the photons was large in comparison to the size of a photon.
The “near field” means working with an extremely small gap between the layer generating the photons and the layer collecting them. In MTPV’s first-generation chips, that gap is 100 nanometres – about 500 times thinner than a human hair.
It took the company from 1998, when it proved the science, to 2001 to create a device that turned the theory into practice and could win a patent. It then took until 2007 to scale that device from 1 sq mm to 1 sq cm.
The company now has three patents, with another six pending relating to different aspects of the design of the TPV arrays.
“In the next three to six months, we expect to start building commercial products,” says Mr Mather. “From there, we have a roadmap for the next 10 to 20 years, as the technology will follow the same pattern as Moore’s law – the chips will double in performance every two years.”
“Our first generation of chips can generate about 1 watt per square cm,” he says, “The science says second-generation chips will be capable of 50-100 watts per square cm.”
The first market that MTPV is looking to exploit is waste heat from industries such as glass manufacturing and energy exploration.
“In the US manufacturing and mining sector alone, 148bn kilowatt hours (kwh) of waste heat is generated every year, while US retail sales of energy amount to just 338bn kwh,” says Mr Mather.
However, while a relatively high number of factories around the world generate the temperatures of 800-1,400 degrees needed to make the first-generation products worthwhile, it is the potential uses of second-generation chips that are more impressive, as the temperatures needed would be far lower.
“Once we get up to 50w/cm the solid-state chips could be used for central power distribution. By that, I mean the chips would be the primary source of electricity,” says Mr Mather.
Exciting as the concept of a solid-state chip that can generate electricity appears, MTPV has just 11 years left on its first patent. “We are already looking at blocking patents to cover our second generation products,” says Mr Mather.
In a highly competitive marketplace, even a fundamental scientific discovery is only the first step on a long and tortuous road.
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