Panasonic Corp announced that it has conducted a verification test of a thermoelectric tube and confirmed a power generation capability of 820W/m3 with waste heat of 96°C water.
In terms of installation area, the tube has about four times higher power generation capability than that of solar power generation, the company said.
The tube is a pipe-like thermoelectric transducer made by alternately stacking a bismuth tellurium (Bi-Te)-based thermoelectric material layer and metal layer in a way that makes them slanted against the flow of heat.
When hot water is flowing in the pipe and cold water is cooling the outside of the pipe, a periodic temperature distribution is generated inside the device. As a result, a current flows in the direction vertical to the heat flow (in the direction of the pipe's axis). The thermoelectric tube can generate electricity even with a small temperature difference.
The verification test has been conducted at "Tohokubu Clean Center," a waste treatment plant in Sakyo-ku, Kyoto City, as a project of Japan's New Energy and Industrial Technology Development Organization (NEDO). To generate electricity from waste heat, Panasonic replaced some of the hot and cooling water pipes in the plant with three thermoelectric units containing 10 thermoelectric tubes each.
Specifically, Panasonic generated up to 246W of electricity with a temperature difference of 91°C by using 96°C hot waste water and 5°C cooling water. The amount of power generated per volume exceeded a designed value by 10% or more. And the thermoelectric equipment had been stably operating for more than 200 hours, the company said.
Panasonic will continue the verification test at the waste treatment plant, aiming to improve the reliability of the thermoelectric unit. In addition, it plans to develop a versatile system that can be easily introduced to existing facilities as well as technologies for volume production of the thermoelectric tube.