Generating ‘Green’ Electricity: Waste Heat Converted to Electricity Using New Alloy
Engineering researchers in the College of Science and Engineering at the University of Minnesota have recently discovered a new alloy material that converts heat directly into electricity. This revolutionary new energy conversion method is in the early stages of development, but it could have a wide-sweeping impact on the process of creating environmentally friendly electricity from waste heat sources.
Researchers stated that the material could potentially be utilized to capture waste heat from a car’s exhaust that would heat the material and produce electricity for charging the battery in a hybrid car. Other potential future uses include capturing rejected heat from industrial and power plants or temperature variations in the ocean to create electricity. The research team is looking into the possible commercialization of the technology.
“This research is very encouraging as it provides a totally new method of energy conversion that has never been performed before,” said University of Minnesota aerospace engineering and mechanics professor Richard James, who led the research team.”It’s also the ultimate ‘green’ way to create electricity because it uses waste heat to create electricity with no carbon dioxide.”
The research team combined elements at the atomic level in order to generate a new multiferroic alloy, Ni45Co5Mn40Sn10. Multiferroic materials combine unusual elastic, magnetic and electric attributes. The alloy Ni45Co5Mn40Sn10 attains multiferroism by experiencing a highly reversible phase transformation where one solid transforms into another solid. During this phase transformation the alloy experiences alterations to its magnetic properties that are utilized in the energy conversion device.
In the course of a small-scale demonstration in a University of Minnesota lab, the new material created by the researchers starts as a non-magnetic material, then abruptly becomes strongly magnetic when the temperature is increased by a small amount. When this occurs, the material absorbs heat and automatically generates electricity in a surrounding coil. Some of this heat energy is dissipated in a process called hysteresis. A significant discovery of the team is a systematic method to minimize hysteresis in phase transformations. The team’s research was recently published in the first issue of the new scientific journal Advanced Energy Materials.
In addition to Professor James, fellow members of the research team include University of Minnesota aerospace engineering and mechanics post-doctoral researchers Vijay Srivastava and Kanwal Bhatti, and Ph.D. student Yintao Song. The team is also working together with University of Minnesota chemical engineering and materials science professor Christopher Leighton to produce a thin film of the material that could be used, for example, to convert some of the waste heat from computers into electricity.
“This research crosses all boundaries of science and engineering,” James said. “It includes engineering, physics, materials, chemistry, mathematics and more. It has required all of us within the university’s College of Science and Engineering to work together to think in new ways.”
Funding for early research on the alloy came from a Multidisciplinary University Research Initiative (MURI) grant from the U.S. Office of Naval Research (involving other universities including the California Institute of Technology, Rutgers University, University of Washington and University of Maryland), and research grants from the U.S. Air Force and the National Science Foundation. The research is also tentatively financed by a small seed grant from the University of Minnesota’s Initiative for Renewable Energy and the Environment.