|A cross-section of nano-crystalline bismuth antimony telluride grains, as viewed through a transmission electron microscope. Colors highlight the features of each grain of the semiconductor alloy in bulk form. Click to enlarge. Image: Boston College, MIT, and GMZ Inc.|
GMZ Energy has the commercial availability of a new thermoelectric material that is more efficient at converting waste heat into power. The material, a nanostructured bismuth antimony telluride, was developed by researchers at Boston College and MIT and realizes an increase in the alloy’s figure of merit—a dimensionless term calculated to indicate a material’s relative thermoelectric performance—from 1 to a peak of 1.4. (Earlier post.)
The GMZ material has a range of capabilities and applications, which includes the ability to optimize cooling in refrigerators and air conditioners and to generate power from heat sources such as automotive exhaust systems.
The GMZ process crushes the bismuth antimony telluride alloy into nanoparticles which are then heated and pressed back together. The grains and irregularities of the reconstituted alloy increased phonon scattering, radically transforming the thermoelectric performance by blocking heat flow while allowing the electrical flow. Phonons, a quantum mode of vibration, play a key role because they are the primary means by which heat conduction takes place in insulating solids. As a result, the material has the unique power to slow down heat flow while allowing electrical flow, thereby redirecting heat to drive electrons and energy rather than escape. The GMZ material delivers that ability to manage, direct and optimize energy on a new scale to the products that use it.
The low-cost approach is detailed in a recent issue of the journal Science.
The use of thermoelectric materials in clean technology has long been overlooked due to high costs and low efficiency, and we’ve overcome those challenges. We’re very excited about the efficiency gains our technology allows, and GMZ Energy is well-positioned to deliver a commercially available material today and help facilitate its use in everyday products.—Mike Clary, CEO of GMZ Energy
In the near-term, the GMZ material will be used in cooling applications and to create products that consume less energy or capture energy that would otherwise be wasted. Longer term, it can provide more advanced solutions, such as cars partially powered by the exhaust system and solar thermal panels with heightened performance.
The GMZ material, currently in advanced testing stage at select US and Asia-Pacific manufacturers and being sampled by early customers, integrates into existing and new product designs for a rapid time-to-market. GMZ Energy is producing the material in pre-production volume at its multi-ton manufacturing facility. Previously, producing such a material was complex work with multiple steps of nanotechnology engineering. GMZ Energy pioneered a simple manufacturing process that makes the thermoelectric material cost-effectively and at high enough volume to be commercially viable.
GMZ Energy was formed by Gang Chen of MIT, Zhifeng Ren of Boston College and CEO Mike Clary to make the innovation market-ready and commercially available for a broad range of business and consumer applications.
Bed Poudel, et. al, , Science (20 March 2008) DOI: 10.1126/science.1156446
(John Fairbanks, DOE, DEER 2007)