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New alloy converts heat directly into electricity


June 24, 2011

A newly-created alloy (center disc) is able to convert heat directly into electricity (Image: University of Minnesota)

A newly-created alloy (center disc) is able to convert heat directly into electricity (Image: University of Minnesota)

The heat given off by electronics, automobile engines, factories and other sources is a potentially huge source of energy, and various technologies are being developed in order to capture that heat, and then convert it into electricity. Thanks to an alloy that was recently developed at the University of Minnesota, however, a step in that process could be saved - the new material is able to convert heat directly into electricity.

The multiferroic alloy, with the catchy name Ni45Co5Mn40Sn10, was created by combining its various elements at the atomic level. Multiferroic materials are known for having unique elastic, magnetic and electric properties, and in the case of this alloy, that takes a form of an usual phase change. When heated, the non-magnetic solid material suddenly becomes a strongly magnetic solid.

In a lab test, upon becoming magnetic, the material absorbed heat in its environment and proceeded to produce electricity in an attached coil. Although some of the heat energy is lost in a process known as hysteresis, the U Minnesota researchers have developed a method of minimizing that energy loss.

"This research is very promising because it presents an entirely new method for energy conversion that's never been done before," said 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 was recently published in the journal Advanced Energy Materials.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

So... what\'s the difference from an good old thermocouple?


Efficiency? Thermocouples are about 6%. Which is enough to use them as temperature sensors. I know they are just at the beginning of this, but some numbers would be good.....


Something that converts heat DIRECTLY into electricity??... boy, this is good... no wait, potentially revolutionary, if they can keep the numbers look good...

Windmaster Hiroaki

Yes, some numbers would be very good, but I still think this seems like a better solution than a thermocouple. If you could coat the object in question in a layer of this and have perfect contact, it seems to me you\'d have a better chance of turning more of the heat into electricity. (not that I know, but I\'m guessing)

In any case, I am excited to see this. Sounds like good progress in the right direction.


If it is over 30% it would be great for solar reflecting dishes. That saves a lot of expense and complication over heat engines. At 40% it would blow them out of the water. Of course, making the material in bulk may not be so easy. The elements themselves don\'t look too costly. A lot of details left out. If it is 5% efficient that would not be much of a game changer.

Peltiers can work in reverse, I wonder it this can be coaxed to as well. Could make a good cooler. I am probably dreaming.


I meant by cooling, not by heating ;)


I wouldn\'t get my hopes up. The process seems to be a sudden change in magnetic properties at reaching a certain temperature. This would create a single magnetic pulse, inducing a single electrical spike. This could be measured, but not useful. You need a cyclic induction to get useful power out. Perhaps if they find a way for this material to swiftly oscillate between magnetic states it would become useful, but in most cases thermal reactions are quite slow.


If this material could be buried under pavement, wow! Roads and parking lots turn into electricity generators. How about roof tops? Stay tuned!

George Swan

So, no moving parts? Another application (if it indeed is more efficient than a thermocouple) would be deep space probes. They currently run on electricity from thermocouples that get their heat source from atomic decay.


this would be perfect for a company with lasers and heating homes

Joshua West

Yeah - a extra set of figures - like say 1000Wm2 onto it and watt it puts out?

\"watt it puts out?\" - get it? - oh ho ho - I am so funny.

Mr Stiffy

As I understand correctly from the article it does produce a continuous flow of energy, but more importantly for how long: hysteresis. It\'s a way of the system being used up like solar panels effeciency rate dropping in time... So what is the ultimate net gain of producing/transporting/developing/... this material.

Philippe Heeren

Sorry, the first link was a previous study of the material. http://onlinelibrary.wiley.com/doi/10.1002/aenm.201000048/full is the paper related to this article with numbers.


Excellent Innovation.


Can a car\'s skin generate enough electricity to power it? It gets very hot here in Vegas.

How does this metal compare to the metal rod used by Biolite to run the fan? Exactly how much heat is needed to start the flow and at what temp do we get a diminishing return?

Can this alloy be combined with photovoltaic cells to use the infrared?


I am wondering if this technology could be used to house battery packs. Then if you have a battery heating up due to heavy load this could possibly relieve the load and dump the heat from the battery at the same time, effectively increasing the out put of a battery pack.

Paul Anthony

Depending on the weight, it may not be practical for use as a heat sink for auto engines- probably take as much energy to haul it as it produces. Also, what about corrosion, both galvanic and oxidation? Multi ferroic implies susceptibility to oxidation, to me. Water and air in the presence of electricity could potentially reduce this material to dust quickly. I think the most promising use for this is in solar panels and in fixed based heat producing plants, such as coal generators and the like. All in all, pretty exciting news!

Steve Anderson

If the gained heat on Magnetic alloy was dispersed like with the electric current from the changed magnetic field. Then the gain in current would be continues. Heated element will swell and radiate any additional gained heat like the radiating process of excess electric current.

Flipider Comm

Imagine if this is added under a solar cell so that in addition to generating electricity from from sunlight energy can be generated from the infra red radiation

Reagon Ramiah

How about making an after market product to add to ICE engines, which would include such a generator and a super capacitor battery. Then when home, plug it in and get paid to put it on the grid! or better yet use it to charge up your commuter EV! Would be great if, like posted before, the efficiency numbers are high!

Facebook User

I love the possibilities. But as a lot of other people making comments, I need the numbers.

This looks like it could be a device that didn't degrade over time or which could be 100% recycled.


Sorry to spoil the fun, but there seems to be a huge drawback. If this device produces electricity by phase shift, then it should be kept hovering about the temperature at which the phase shift occurs. This means that more heat does not necessarily translates immediately to more energy; heat should first be dispersed and cooled to the correct temperature, which might cause rather large waste of energy.

Amos Shapir

Would be neat if something like this could be made into a jumpsuit that powers a smartphone with human body heat. Then you wouldn\'t have to worry about batteries dieing in your smartphone while on the go. You could also then use smaller, cheaper batteries vastly lowering the costs of such devices.

Samantha Renault

How much does it cost? Looks pretty darn expensive not just with the considerable nickel and cobalt content but the very high purity input metals e.g. 99.999% pure nickel and considerable processing such as 24 hours at 900C in an argon furnace. Enough to limit its applications to aerospace and military.

Mark Smith

Why isn't thermocouple technology used to generate power? The temperature differences in volcanic areas where the very high temperature magma is relatively close to the earth's surface and deep sea areas where the there is extremely low temperatures. In both cases the temperature differences compared to surface areas should produce enough temperature gradient

Susantha Gunawardene

Where should find full details of this alloy....some info like relation of magnetism with heat..or it's graphs or anything else...it converts heat into ele. energy....in this process,what it will waste??...can someone suggest??

Kishan Panchal

ahh CO2 is what makes the earth green so actually anything that generates CO2 is the greenest power source ...

oh and from the paper: "Theory predicts that under optimal conditions the performance compares favorably with the best thermoelectrics."

so this matches thermoelectrics ... not exactly earth shattering ... optimal conditions means the lab as compared to real world theromoelectrics ...

cool research ... may actually be useful someday ... give it a decade ...

Jeffrey Carlson
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