Researchers at the University of Tokyo have generated electricity from latent heat, the energy generated when a substance changes from a solid, liquid or gas to another state. This breakthrough will push the possibilities of thermocells, devices that use changes in temperature to generate electricity, known as thermoelectric conversion.
As all materials are capable of undergoing phase transitions under the right conditions, this research supports the idea that a wide variety of materials have the potential to be used for thermoelectric conversion. -o. Latent heat that was previously wasted can now be used to enable devices to generate their own energy while cooling themselves, reducing dependence on other energy sources.
We hit the hottest day on record on Earth this summer. Rising summer temperatures and increasing use of technology mean the demand for cooling systems for home and industry is growing. Air conditioning and refrigeration technologies are already leading energy users, so meeting this growing demand is a challenge for countries trying to achieve their United Nations’ Sustainable Development Goals. to improve the environment and people’s lives.
But what if we could use at least some of the waste generated by these cooling systems to help generate the electricity needed to run them, in a cheap, low-carbon way?
Researchers at the University of Tokyo became interested in the potential of latent heat energy that is generated when a part of a substance changes from one state to another, for example, when the water inside an air conditioner evaporates and condenses to create a cooling effect. Unlike the hot air you feel blasting outside from an aircon unit, the latent heat generated by the water inside is barely noticeable. Thermoelectric conversion uses heat to generate electricity, and one device that can do that is a thermocell. The work is published in the journal Advanced Materials.
The team created their own thermocell using a hydrogel—a polymer material filled with water—called PNIPAM, which they modified with a compound called viologen. This modified hydrogel contains a thermo-responsive polymer, meaning that the polymer reacts to changes in temperature, in this case soluble in cold water but insoluble in hot water. With this thermocell, they were able to successfully use the very small amount of latent heat energy generated by the phase transition—between melt and non-melt—to generate electricity.
“For the first time, we have confirmed that latent heat has the potential to be used for thermoelectric conversion,” said Professor Teppei Yamada from the Department of Chemistry at the University of Tokyo’s Graduate School of Science.
“We believe that we can use different types of materials for thermocells. Every substance in the world can phase transition under the right conditions: for example, cream to ice-cream, sand to glass, water to of steam, etc. with this method, in that principle, it is possible to obtain electrical energy from even a small difference in temperature, greatly increasing the number of situations in which thermoelectric conversion can be used.”
The performance of a thermocell is assessed by how much voltage can be obtained from a small temperature difference, called the Seebeck coefficient. The higher the Seebeck coefficient, the more electrical energy is obtained.
The Seebeck coefficient of thermocells using organic compounds is usually less than 1 microvolt (one millionth of a volt) per Kelvin unit of temperature, but in this test they exceeded 2 microvolts per kelvin. “It’s an incredible achievement,” Yamada said. “Although we have previously created thermocells that produce 2 microvolts per Kelvin by using a pH change, this is the first time that the energy from a phase transition has been used directly.”
The researchers hope that this work will help improve refrigeration technology, temperature management devices and other temperature sensors. “We have reached the stage where we can consider practical applications of thermocells. For example, we expect it to be possible to generate electricity while cooling a server room or the engine of a car,” said Yamada.
“The real challenge now is that this technology is not well known, so we need industry, government and academia to work together to achieve rapid social implementation.”
Hongyao Zhou et al, Direct Conversion of Phase-Transition Entropy to Electrochemical Thermopower and Peltier Effect, Advanced Materials (2023). DOI: 10.1002/adma.202303341
Provided by the University of Tokyo
Citation: Using latent heat to generate electricity while cooling primary devices (2023, July 18) retrieved 18 July 2023 from https://techxplore.com/news/2023-07-latent-generate- electricity-cooling-primary.html
This document is subject to copyright. Except for any fair dealing for the purpose of private study or research, no part may be reproduced without written permission. Content is provided for informational purposes only.