Tapping industrial heat could cut fossil fuels use

April 2nd, 2009 - 5:25 pm ICT by IANS  

Washington, April 2 (IANS) Tapping waste heat from industries could cut down fossil fuel use and improve efficiency of countless manufacturing processes, says a study.
According to Lihua Zhang and Tomohiro Akiyama of Hokkaido University, Japan, heat waste from industrial processes, such as combustion and electricity generation, is sometimes of low energy and diffuse and capturing this low-quality heat for re-use elsewhere on an industrial plant is usually not practical.

However, given current environmental and economic pressures, the recuperation of such heat energy could become viable.

The study aimed to find a way to capture the heat from industrial furnaces and other systems without the constraints of time and space associated with simply using the heat to produce steam to drive other processes at precisely the same site.

The team investigated three promising technologies for heat recovery: latent heat, reaction heat, and the use of a thermoelectric device, and say their approach can “recuperate industrial waste heat beyond time and space.”

Key to making heat recuperation viable is understanding the nature of the energy involved.

For example, 95 percent of the waste heat in the electric power industry has a temperature below 150 degrees Celsius. Conversely, 45 percent of the waste heat in the chemical industry can be up to 50 degrees Celsius above this.

Zhang and Akiyama, however, point out that high-temperature waste heat exists in many manufacturing industries, said a Hokkaido release.

For example, slag and exhaust gases from steel making are well over 1,000 degrees Celsius, representing a powerful energy source and according to the researchers, latent heat storage, chemical storage, and thermoelectric conversion could be used as effective ways of recovering waste heat, either individually or in combination.

These findings were published in the International Journal of Exergy.

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