A low-cost thermoelectric waste heat recovery system to reduce both energy use in the industrial sector and electricity-related carbon emissions is being developed by the U.S. Department of Energy’s Lawrence Berkeley National Lab and Alphabet Energy. In California alone, such technology could potentially save up to $385 million annually, 3.2 million MWh/year, and increase electrical reliability.

Industrial facilities in the state, such as power plants, cement plants, and manufacturing facilities, can potentially harness more than 763 MW of electricity-generating potential from waste heat. The national potential is estimated at 15,000 MW.

Thermoelectrics harvest exhaust heat from engines, furnaces, and other sources of waste heat and convert it to useful energy without generating additional greenhouse gas emissions. Commercially available thermoelectrics, which have already seen some market traction in the oil and gas and automotive industries, achieve less than 5 percent conversion efficiency.A thermoelectric device by Alphabet Energy (Courtesy Alphabet Energy)A thermoelectric device by Alphabet Energy (Courtesy Alphabet Energy)

The research seeks to overcome current limitations of available thermoelectric materials, including high cost, low efficiency, and the inability to operate reliably at temperatures above 400 C (752 F). A prototype device will be built and tested using advanced thermoelectric materials based on silicon nanowires developed by Hayward, CA-based Alphabet Energy. These materials feature conversion efficiencies of 10% or greater and the ability to operate at temperatures up to 800 C (1472 F).

Higher efficiencies and operating temperatures could lead to improved remote power generation as well as new applications, such as increased power production with high-temperature waste heat captured from gas flares.

The project received a $2-million grant from the California Energy Commission’s Electric Program Investment Charge program, which funds clean energy innovation to reduce pollution, foster economic development, and meet the state’s climate goals.