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Left to Right: Richard James, Yintao Song, Kanwal Bhatti and Vijay Srivastava  (Source: University of Minnesota)
The new multiferroic alloy is called Ni45Co5Mn40Sn10

A new step toward environmentally friendly electricity has been made through the discovery of a new alloy material that converts heat into electricity directly. 

Richard James, study leader and University of Minnesota aerospace engineering and mechanics professor, along with University of Minnesota aerospace engineering and mechanics post-doctoral researchers Vijay Srivastava, Kanwal Bhatti and Ph.D. student Yintao Song, have used a new alloy to create electricity from heat. This could eventually lead to capturing waste heat from car exhaust and using it to create electricity for a hybrid car battery, thus recycling energy.

The material was created through the combination of elements at the atomic level. This led to the development of a new multiferroic alloy called Ni45Co5Mn40Sn10. This alloy underwent a "highly reversible" phase transformation where a solid turns into another solid, and during this transformation, its magnetic properties changed. These changes show in the energy conversion instrument. The material starts out as non-magnetic, and then becomes increasingly magnetic as the temperature increases. The material absorbs the heat and produces electricity in a coil.

Some of the recovered heat is lost through the process hysteresis, but the University of Minnesota team found a way to reduce this process and absorb more heat. 

"This research is very promising because it presents an entirely new method for energy conversion that's never been done before," said James. "It's also the ultimate 'green' way to create electricity because it uses waste heat to create electricity with no carbon dioxide." 

The team is also working on making a thin film of the material to convert heat from computers into electricity. 

"This research crosses all boundaries of science and engineering," said James. "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."

This study was published in Advanced Energy Materials.

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Less talk more make
By BugblatterIII on 6/27/2011 3:16:24 PM , Rating: 3
Turning heat into electricity seems to be the new fad on here; we seem to get one a week.

I didn't read the links so correct me if I've missed something, but to generate electricity requires a changing magnetic field. Something going from non-magnetic to magnetic once will produce almost nothing.

RE: Less talk more make
By Solandri on 6/27/2011 4:15:07 PM , Rating: 3
You don't have to go straight from magnetism to electricity. As a simple thought experiment, imagine this material mounted on a wheel, sitting above a steel base. As it heats up and becomes magnetic, it is attracted to the base and spins the wheel towards it. The moves it further from the heat source, allowing it to cool, causing it to become non-magnetic and allowing the wheel to spin further. Repeat. You can then hook up the wheel to a electric generator.

But as someone pointed out above, at its current level of efficiency, it'd be like putting dixie cups on a ferris wheel and expecting rain falling in the cups to spin the ferris wheel. If they can raise its efficiency substantially, it might go somewhere. Otherwise it'll just remain a curiosity of physics.

RE: Less talk more make
By SPOOFE on 6/27/2011 7:09:37 PM , Rating: 2
If they can raise its efficiency substantially, it might go somewhere.

Or make it super, super cheap, which I doubt. If it were no more expensive than conventional materials or construction methods, then even a tiny tiny increase would be worth it. But again, I doubt it'll happen.

RE: Less talk more make
By FaaR on 6/29/2011 11:19:03 AM , Rating: 3
Nice thought experiment, but even discounting the weak magnetism it would produce and thus the tiny torque it would generate (perhaps less than resistance from bearings and generator) it would probably need to spin for thousands of years just to recoup the energy spent on its construction, much less give a net surplus...

These sort of ideas are always hare-brained right from the outset. There's hardly any energy to be gained, and the resources spent into R&D could have been better spent elsewhere. Unavoidably these schemes tend to smell like a fishing expidition for venture capital from science-ignorant investors who don't realize that they'll never see a return on their money, making the whole thing little more than a scam.

RE: Less talk more make
By JediJeb on 6/27/2011 5:10:46 PM , Rating: 2
Seems like you would need the heat pulsed to keep the magnetic field fluctuating to generate electricity by the way the article says it.

Efficiency seem lower than that of a thermocouple. Correct me if I am wrong but weren't Voyager and Pioneer powered by Thermopiles which are nothing but arrays of thermocouples powered by the heat of a radioactive isotope? Why can't we wrap car exhaust systems in a bunch of thermocouples to make electricity from the waste heat?

RE: Less talk more make
By Fritzr on 6/27/2011 9:38:45 PM , Rating: 3
Why can't we wrap car exhaust systems in a bunch of thermocouples to make electricity from the waste heat?

In production. Low efficiency compared to mainstream power production, but there are applications such as the exhaust system of a truck tractor. Google "Peltier" which is the most common form of this device. Some of these are used as actively powered coolers, others generate power while drawing heat from a substrate.

Old news so they won't make the headlines again until there is an unusual application or a substantial increase in efficiency.

Another heat driven power generator is a Stirling Cycle engine driven generator, which can be powered by exhaust heat with the cold side behind a wall that screens it from the waste heat source.

A couple of existing production solar heated Stirling Cycle generators are a device that powers a satellite, and a ground version that uses what looks like a satellite dish to focus sunlight on the hot side of the engine.

Another one is available that drives a small fan and is powered by a cup of hot coffee. There is no reason these cannot be harnessed to draw power from waste steam in a conventional power plant, or the exhaust heat from a combustion engine or firebox.

RE: Less talk more make
By mindless1 on 6/28/2011 6:56:45 PM , Rating: 2
Why can't we wrap car exhaust systems in a bunch of thermocouples to make electricity from the waste heat?

1) It would create a trivial amount of electricity.

2) The higher exhaust backpressure from (further) cooling the exhaust would "probably" put enough additional drag on the engine to exceed the amount of drag by just producing more electricity through the alternator.

3) It would add significant cost, and reduce lifespan, and increase repair costs to add to what is now a pretty simple car subsystem (beyond the application of the precious metals in the catalytic convertor(s)).

4) Adds weight, not just the energy production portion but wiring, shielding, more robust hanger/bracket system.

"We don't know how to make a $500 computer that's not a piece of junk." -- Apple CEO Steve Jobs

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