Waste heat turns into energy

 By Benjamin Plackett

Today’s technology wastes a lot of energy. Close to 70 percent of energy in the United States, for example, is wasted through heat loss, according to experts. This waste heat is usually less than 100 degrees Celsius and comes from cars, computers and industrial processors. Now, engineers have invented a thin film-like material that coats the surface where waste heat is emitted, and it turns into usable energy. They published their findings in the Nature Materials journal last month…

“Applications that take advantage of this wasted resource stand poised to impact the reduction of carbon emissions and could ultimately translate to huge financial savings,” says lead author Lane Martin, associate professor of materials science and engineering the University of California, Berkeley.
He sees research and innovation like this as one line of attack against energy insecurities and global warming.
“We need new energy sources, but we also need to do better at using the energy we already have,” says Martin. “These thin films can help us squeeze more energy than we do today out of every source of energy.”

A new energy breakthrough

Martin and his team have developed material that can absorb heat and turn it into stored energy much more efficiently than similar technologies have attempted to do in the past.
The film is extremely thin — on the nanoscale, which may limit the trouble caused in introducing a new component to the manufacturing process of consumer electronics or larger scale industrial machines.
“When your laptop is sitting on your lap and gets hot, when you feel the hot exhaust coming out of an automobile, when you see large cooling towers at a power plant — all of these things are sources of energy in the form of lost heat,” says Martin, “If we can tap into this resource and extract more energy form that initial unit of energy we put into the system, we can really make an impact on the environment and on the economy around the world.”
The new film is what’s known as a pyroelectric material. This means it has a spontaneous polarization, which creates an electric charge. The spontaneous polarization of the new material in question is influenced by temperature changes. Martin connected capacitors to the film so that when the temperature increases, an electrical circuit can capture the heat energy.
“We found that we have a material that is really good at doing this type of energy conversion,” says Martin, “We took that knowledge and designed demonstration devices that allowed us to test the viability of the material for applications. Turns out it was very good!”

Filling up the gaps

Getting this far has taken years of work and despite the clear potential in reducing wasted energy, Martin found the topic surprisingly lacking in previous research.
“We came to this general area a few years ago because it was one of the least well understood realms of science for these materials. It turns out that the physics is complicated,” he says.
The lack of previous knowledge clearly motivates Martin in his quest to make us use energy more efficiently.
“It was basically the ‘wild west’ in terms of observations and knowledge,” he says, “One of the best parts of my job is we get to discover and understand new things and fill in unmapped or poorly understood parts of our knowledge.”
Martin is excited about his findings, which exemplify the role of science and innovation in improving the way energy is consumed, but he cautions it could still be some time before his device is ready to be applied to consumer products or industrial engines.
“A consumer device based on what we report in the manuscript is still quite a ways off — there is a long road between the laboratory demonstration we’ve completed and something you can buy from Amazon or the like, but this is where that road starts,” he says.
Although he does admit this material is more likely to be used in new products and machines at the time of their original manufacture, rather than something that could be retrospectively applied.
“Having an end user just slap this on down the line might come with extra inefficiencies that would limit the impact the technology might have,” he says, “Building this in during the original manufacturing is probably more likely.”

READ MORE: Where there is waste there is energy by Nicholas Newman

about the author
Benjamin Plackett
I’m a journalist based in London. I report on all things science, tech, and health for a number of different publications. My work has been published by The Daily Dot, Inside Science and CNN among others. I earned my M.A. in Journalism at New York University and my B.Sci in Biology from Imperial College, London.