Novel Device Harvest Waste Heat and Turn it Into Electricity

There are many processes, especially industrial ones, that generate waste heat without it being their primary purpose.

This waste heat, in the form of thermal energy, can be harvested and used to generate energy, like electricity or mechanical power.

Waste heat recovery systems could significantly improve the energy efficiency of fossil fuel-powered plants and other heat-generating facilities, shrinking their carbon footprint.

Granted, some facilities might just be driven by profitability than ecological concerns in their search for efficient systems to recover unwanted heat, but the result would be environmentally beneficial all the same.

A Cool Way to Turn Waste Heat Into Electricity

Heat will leak out no matter what. But, systems don’t have to let this energy fritter away into the atmosphere.

Take solar panels, for instance. They lose heat to the air as wasted energy, while producing energy is their only mission.

Rice University scientists designed a new waste heat recycling device that, according to the team, would make solar panels, and other heat energy-leaking systems far more efficient.

They aligned arrays of carbon nanotube films into single walls that “channel mid-infrared radiation (aka heat) and greatly raise the efficiency of solar energy systems.”

The carbon nanotube films absorb the thermal energy of photons then releases it as narrow bandwidth light recyclable as electricity.

Junichiro Kono from Rice’s Brown School of Engineering and one of the paper’s co-authors explains that thermal photons are:

“ Just photons emitted from a hot body. If you look at something hot with an infrared camera, you see it glow. The camera is capturing these thermally excited photons.”

Infrared radiation is what delivers heat to our planet, but it’s only a small part of the electromagnetic spectrum.

Any molten material emits light as thermal radiation, which is a component of sunlight that comes in broadband, and this is a problem.

Light can be converted into electricity only in a narrow band but this is where Rice’s new device comes in – by squeezing broadband thermal photons emitted into a narrow band.

Each year, billions of kilowatt-hours of thermal energy dissipate into the environment while it could be tapped into as a valuable source to generate electricity. In the U.S., 60 percent of the power used by industrial, commercial, and residential consumers is waste heat.

The device developed at Rice can turn wasted thermal energy into electricity with a theoretical 80% efficiency.

The researchers detailed their new technology aimed at enhancing the efficiency of waste heat recovery systems in the journal ACS Photonics.