Direct conversion from heat to electricity

There are two reasons I really like this story.

First of all, there is this small matter about where this happened--The University of Minnesota.  The state spends a LOT of tax money to support her flagship public school and it nice to know they can still do very smart things over on campus.  This practice is hardly new--it is almost impossible to imagine 3M in its heyday without the chemistry department at U of M, while the large and diversified medical equipment industry in Minnesota simply would not have happened without the labs next to the U of M hospital.  So the idea of throwing a LOT of hard science at problems with potential commercial applications seems built into the school's mission.  Rah! Rah! Rah! for Ski-U-Mah! (etc.)

And then there is my PET argument that environmental problems are usually ENGINEERING problems.  This is especially true when the subject is energy--whether it's finding or extraction, refining or distribution, or the production of the devices that use energy, virtually every problem of importance can only be solved by people who are very comfortable around science and ingenious deploying technology.  ("My people" you understand.)

University of Minnesota engineering researchers discover source for generating 'green' electricity

Published: Wednesday, June 22, 2011 - 13:38 in Physics & Chemistry

University of Minnesota engineering researchers in the College of Science and Engineering have recently discovered a new alloy material that converts heat directly into electricity. This revolutionary energy conversion method is in the early stages of development, but it could have wide-sweeping impact on creating environmentally friendly electricity from waste heat sources. Researchers say the material could potentially be used 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 possible future uses include capturing rejected heat from industrial and power plants or temperature differences in the ocean to create electricity. The research team is looking into possible commercialization of the technology.

"This research is very promising because it presents an entirely new method for energy conversion that's never been done 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."

To create the material, the research team combined elements at the atomic level to create a new multiferroic alloy, Ni45Co5Mn40Sn10. Multiferroic materials combine unusual elastic, magnetic and electric properties. The alloy Ni45Co5Mn40Sn10 achieves multiferroism by undergoing a highly reversible phase transformation where one solid turns into another solid. During this phase transformation the alloy undergoes changes in its magnetic properties that are exploited in the energy conversion device.

During a small-scale demonstration in a University of Minnesota lab, the new material created by the researchers begins as a non-magnetic material, then suddenly becomes strongly magnetic when the temperature is raised a small amount. When this happens, the material absorbs heat and spontaneously produces electricity in a surrounding coil. Some of this heat energy is lost in a process called hysteresis. A critical discovery of the team is a systematic way 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. more