Low-Cost High-Reliability Thermoelectrics for Waste Heat Conversion
A cost-effective mid- to high-temperature range (400-800C) thermoelectric material for waste heat recovery
Lawrence Berkeley National Laboratory
Recipient
Berkeley, CA
Recipient Location
9th
Senate District
14th
Assembly District
$2,000,000
Amount Spent
Completed
Project Status
Project Result
Lawrence Berkeley National Laboratory and Stanford University developed a novel and cost-effective process for creating advanced thermoelectric materials constructed from silicon nanowire arrays, and characterized the thermoelectric performance of the arrays between the temperatures of 300 Kelvin and 700 Kelvin. This project will lead to technological advancements and breakthroughs that will help provide low-cost, reliable, affordable, and mass-producible waste-heat recovery technologies that can be ubiquitously applied to convert high-temperature waste heat at the production and retail levels to electricity in California.
The Issue
Current commercially available thermoelectric materials can only operate reliably up to 250 degrees C in temperature and have a low efficiency (5 percent). Materials that have been evaluated at higher temperature suffer from reliability issues due to use of lead and oxidation and sublimation problems. Silicon is abundant and stable at high temperature and thermoelectric devices made from Si hold much promise, though bulk Si has a low figure-of-merit. One established strategy for increasing figure-of-merit is to employ nanostructuring to decrease thermal conductivity. Silicon nanowires represent a new, highly-scalable technology that overcomes the limitations of previous efforts.
Project Innovation
This project is developing a cost-effective mid- to high-temperature range (400-800 C) thermoelectric material for waste heat recovery using silicon nanowire arrays. The intent is to surpass technologies implementing an organic Rankine cycle or similar processes by having low parasitic losses, compact structure, and ability to be modularized for a broad scale of distributed applications. To achieve the goal, the project will advance the state of the art in nanowire characterization; demonstrate an optimized process for the production of Si nanowire arrays and a process to produce a freestanding array of aligned nanowires; characterize the thermoelectric and mechanical properties of these arrays and single Si nanowire; optimize the fabrication of the Si nanowire arrays; and integrate these arrays into devices capable of heat-to-power conversion. The results of device performance will be used to evaluate the techno-economic impacts of this technology.
Project Benefits
This project will address principal barriers to the widespread application of current thermoelectric materials by providing a low-cost, reliable, affordable, and mass-producible technology that can be broadly applied to convert high-temperature heat that is currently wasted at the production and retail levels in California.
Economic Development
The total waste heat potential in California is 763 megawatts. Assuming a system cost of $1.5/watt and a 10 percent penetration, the estimated levelized cost of electricity is $0.015/kWh.
Reliability
This project will create a cost-effective Thermoelectric Waste Heat Recovery system that will reduce energy use in the industrial sector, thus benefitting California ratepayers by increasing electrical reliability.
Energy Security
Based on the assessment sponsored by Oak Ridge National Laboratory, the total potential net savings in electricity use per year from harvesting waste heat is about 0.022 quads for California.
Key Project Members
Ravi Prasher
Subrecipients
The Leland Stanford Junior University
Match Partners
The Leland Stanford Junior University
