Research Shows Nanotube Thermocells Can Be Excellent Power Sources

According to a study published in the American Chemical Society’s Nano Letters journal, researchers at the University of Texas at Dallas have determined that thermocells based on carbon nanotube electrodes could be used for generating electrical energy from heat cast off by chemical plants, automobiles and solar cell farms.

Researchers found that efficient harvesting of the thermal energy that is currently wasted by industrial plants or along pipelines could create clean energy, which in turn could be used to lower costs and shrink an organization’s energy footprint. The new thermocells use nanotube electrodes that reportedly provide a threefold increase in energy conversion efficiency over conventional electrodes.

One of the demonstrated thermocells resembles the button cell batteries used in watches, calculators and other small electronics. However, unlike those common household batteries, these thermocells reportedly can continuously generate electricity, instead of running down. The research also discovered electrolyte-filled, textile-separated nanotube sheets that can be wrapped around pipes carrying hot waste streams of manufacturing or electrical power plants. The temperature difference between the pipe and its surroundings produces an electrochemical potential difference between the carbon nanotube sheets, which thermocells utilize to generate electricity.

The research was led by Ray Baughman, the Robert A. Welch Chair in Chemistry and director of the Alan G. MacDiarmid NanoTech Institute, who collaborated with an international team of researchers from the United States, Australia, China, India and the Philippines.

The research team estimates that multi-walled carbon nanotubes in large thermocells could eventually produce power at a cost of ~$2.76/W from freely available waste energy, compared with a cost of $4.31/W for solar cells, which can only be used when the sun is shining. On a smaller scale, button-cell-sized thermocells could be used to power sensors or electronic circuits. The new thermocells take advantage of the electronic, mechanical, thermal and chemical properties of carbon nanotubes. The nanotubes’ large surface area and unique electronic structure afforded by their small diameter and nearly 1-D structure offer high current densities, which enhance the output of electrical power and the efficiency of energy harvesting.

Researchers report they will continue working on the technology to develop commercial applications and seek out advances. The research was sponsored by the Office of Naval Research, the National Science Foundation, the Welch Foundation and the Australian Research Council.