Vast amounts of energy are wasted every year in the form of heat. A new project led by the Department of Energy's Lawrence Berkeley National Lab (Berkeley Lab) seeks to efficiently capture that heat and convert it to electricity, potentially saving California up to $385 million per year.
With a $2-million grant from the California Energy Commission (CEC), Berkeley Lab is partnering with Alphabet Energy to create a cost-effective thermoelectric waste heat recovery system to reduce both energy use in the industrial sector and electricity-related carbon emissions. ICF International estimates that such a system could save California 3.2 million megawatt-hours per year in energy while also increasing electrical reliability. The funding comes from CEC's Electric Program Investment Charge (EPIC) program, which funds clean energy innovation to reduce pollution, foster economic development, and meet the state's climate goals.
"The potential to create electricity from waste heat in California has not been tapped significantly due to the lack of suitable waste-heat-to-electricity conversion technology," said Ravi Prasher, director of Berkeley Lab's Energy Storage and Distributed Resources Division. "Thermoelectrics is one of the most promising technologies for waste heat conversion out there, but the biggest challenge has been to find a reliable and cost effective material that can work at high temperatures."
Industrial facilities, such as power plants, cement plants, mining and manufacturing facilities, and oil and gas operations have more than 763 megawatts (MW) of electricity-generating potential from waste heat in California, and national potential is approximately 15,000 MW. However, most current thermoelectric materials are limited by several factors, including high cost, low efficiency, and the inability to operate reliably at temperatures above 400 degrees Celsius.
The new Berkeley Lab project, co-led by Prasher and Vi Rapp, a mechanical research scientist in the Energy Technologies Area, is working to overcome these barriers. In collaboration with Alphabet Energy, they will develop a cost-effective process for creating an advanced thermoelectric material constructed from silicon nanowire arrays.
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 achieve less than 5 percent efficiency in converting heat to electricity. The technology has already seen some market traction in the oil and gas and automotive industries.
Alphabet Energy is a Hayward, California-based startup that launched in 2009 using nanotechnology licensed from Berkeley Lab. They are developing advanced thermoelectric materials based on silicon nanowires with conversion efficiencies of 10 percent or greater and the ability to operate at temperatures up to 800 degrees Celsius.
"With the increase in efficiency, other market opportunities in waste-heat-to-power could be accelerated," Rapp said. "For example, an advanced thermoelectric system could improve remote power generation technology, bringing electricity to places without grid access or reliable solar energy."
The higher operating temperature also opens up new possibilities, such as increasing the power produced from capturing high-temperature waste heat from gas flares.
The CEC funding will enable Berkeley Lab and Alphabet Energy to develop a prototype device and validate its performance for high temperature heat-to-electricity conversion.
"Our objective is to develop a new system that has very few parasitic losses, is more compact, is modularized for a broad scale of distributed applications, and will reliably produce additional electricity with almost no maintenance cost or operator involvement for many years," Prasher said. "We believe it will make waste-heat-to-power viable and affordable in a wider spectrum of applications."