Scientists Harness Waste Heat to Create Electricity with New Batteries

First Posted: May 22, 2014 11:26 AM EDT

Scientists may have found a new way to harness the vast amounts of wasted excess heat that are generated by industrial processes and electric power plants. The new findings could mean a revolutionary way to create more electricity, and could ease our strong reliance on fossil fuels.

The new method for converting heat into energy is based on a phenomenon called the thermogalvanic effect. Since the voltage of rechargeable batteries depends on temperature, this new system combines the charging-discharging cycles of these batteries with heating and cooling so that the discharge voltage is higher than charge voltage. In fact, it can harness even small temperature differences.

First, the uncharged battery is heated by the waste heat. While at the higher temperature, the battery is charged. Once fully charged, the battery is allowed to cool and because the charging voltage is lower at high temperature than at low temperature, the battery can deliver more electricity than what was used to charge it.

This new technique is aimed at harvesting heat of less than 100 degrees Celsius; this is especially important to note since it accounts for a large proportion of potentially harvestable waste heat.

"Virtually all power plants and manufacturing processes, like steelmaking and refining, release tremendous amounts of low-grade heat to ambient temperatures," said Yi Cui, one of the researchers, in a news release. "Our new battery technology is designed to take advantage of this temperature gradient at the industrial scale."

While the system has an advantage in energy-conversion efficiency, though, it has a much lower power density for now. In addition, scientists will have to conduct further research to assess its reliability over a long period of use, and to improve the speed of battery charging and discharging.

That said, this new method could be huge for retaining energy. One-third of all energy consumption in the United States ends up as low-grade heat, so being able to harness it could be a good way to bolster energy levels.

The findings are published in the journal Nature Communications.

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