Thermophotovoltaic device turns waste heat into electricity—while defying a physical limit

A group of engineers and materials scientists within the Paul M. Rady Division of Mechanical Engineering at CU Boulder has developed a brand new expertise to show thermal radiation into electrical energy in a method that actually teases the essential legislation of thermal physics.

The breakthrough was found by the Cui Analysis Group, led by Assistant Professor Longji Cui. Their work, in collaboration with researchers from the Nationwide Renewable Power Laboratory (NREL) and the College of Wisconsin-Madison, was just lately published within the journal Power & Environmental Sciences.

The group says their analysis has the potential to revolutionize manufacturing industries by growing power generation with out the necessity for prime temperature warmth sources or costly supplies. They will retailer clean energydecrease carbon emissions and harvest warmth from geothermal, nuclear and photo voltaic radiation crops throughout the globe.

In different phrases, Cui and his group have solved an age-old puzzle: do extra with much less.

“Warmth is a renewable energy source that’s usually missed,” Cui mentioned. “Two-thirds of all energy that we use is turned into heat. Think of energy storage and electricity generation that doesn’t involve fossil fuels. We can recover some of this wasted thermal energy and use it to make clean electricity.”

Breaking the bodily restrict in vacuum

Excessive-temperature industrial processes and renewable power harvesting strategies usually make the most of a thermal power conversion methodology known as thermophotovoltaics (TPV). This methodology harnesses thermal power from excessive temperature warmth sources to generate electrical energy.

However current TPV gadgets have one constraint: Planck’s thermal radiation legislation.

“Planck’s law, one of most fundamental laws in thermal physics, puts a limit on the available thermal energy that can be harnessed from a high temperature source at any given temperature,” mentioned Cui, additionally a school member affiliated with the Supplies Science and Engineering Program and the Middle for Experiments on Quantum Supplies. “Researchers have tried to work closer or overcome this limit using many ideas, but current methods are overly complicated to manufacture the device, costly and unscalable.”

That is the place Cui’s group is available in. By designing a novel and compact TPV system that may slot in a human hand, the group was capable of overcome the vacuum restrict outlined by Planck’s legislation and double the yielded energy density beforehand achieved by typical TPV designs.

“When we were exploring this technology, we had theoretically predicted a high level of enhancement. But we weren’t sure what it would look like in a real world experiment,” mentioned Mohammad Habibi, a Ph.D. scholar in Cui’s lab and chief of each the idea and experiment of this analysis. “After performing the experiment and processing the data, we saw the enhancement ourselves and knew it was something great.”

The zero-vacuum hole answer utilizing glass

The analysis emerged, partly, from the group’s want to problem the boundaries. However with the intention to succeed, they needed to modify current TPV designs and take a special strategy.

“There are two major performance metrics when it comes to TPV devices: efficiency and power density,” mentioned Cui. “Most people have focused on efficiency. However, our goal was to increase power.”

To take action, the group applied what’s known as a “zero-vacuum gap” answer into the design of their TPV system. Not like different TPV fashions that function a vacuum or gas-filled hole between the thermal supply and the photo voltaic cell, their design options an insulated, excessive index and infrared-transparent spacer made out of simply glass.

This creates a excessive energy density channel that enables thermal warmth waves to journey via the system with out dropping power, drastically bettering energy era. The fabric can be very low-cost, one of many system’s central calling playing cards.

“Previously, when people wanted to enhance the power density, they would have to increase temperature. Let’s say an increase from 1,500 C to 2,000 C. Sometimes even higher, which eventually becomes not tolerable and unsafe for the whole energy system,” Cui defined.

“Now we can work in lower temperatures that are compatible with most industrial processes, all while still generating similar electrical power than before. Our device operates at 1,000 C and yields power equivalent to 1,400 C in existing gap-integrated TPV devices.”

The group additionally says their glass design is simply the tip of the iceberg. Different supplies might assist the system produce much more energy.

“This is the first demonstration of this new TPV concept,” defined Habibi. “But when we used one other low-cost materials with the identical properties, like amorphous siliconthere’s a potential for a good larger, almost 20 occasions extra improve in power density. That is what we want to discover subsequent.”

The broader business affect

Cui says their novel TPV gadgets would make its largest affect by enabling transportable energy turbines and decarbonizing heavy emissions industries. As soon as optimized, they’ve the ability to rework high-temperature industrial processessuch because the manufacturing of glass, metal and cement with cheaper and cleaner electrical energy.

“Our device uses commercial technology that already exists. It can scale up naturally to be implemented in these industries,” mentioned Cui. “We are able to get well wasted warmth and may present the energy storage they want with this system at a low working temperature.

“We have a patent pending based on this technology and it is very exciting to push this renewable innovation forward within the field of power generation and heat recovery.”