A new alloy with unique properties can convert heat directly into electricity, according to researchers at the University of Minnesota. The alloy, a multiferroic composite of nickel, cobalt, manganese and tin, can be either non-magnetic and highly magnetic, depending on its temperature.

Multiferroic materials possess both magnetism and ferroelectricity, or a permanent electric polarization. Materials with both of these properties are very rare; check out this explainer from the National Institute of Standards and Technology if you’re interested in the electron orbital arrangements that cause these phenomena.

In this case, the new alloy — Ni45Co5Mn40Sn10 — undergoes a reversible phase transformation, in which one type of solid turns into another type of solid when the temperature changes, according to a news release from the University of Minnesota. Specifically, the alloy goes from being non-magnetic to highly magnetized. The temperature only needs to be raised a small amount for this to happen.
When the warmed alloy is placed near a permanent magnet, like a rare-earth magnet, the alloy’s magnetic force increases suddenly and dramatically. This produces a current in a surrounding coil, according to the researchers, led by aerospace engineering professor Richard James. Watch a piece of the alloy leap over to a permanent magnet in the video clip below.

A process called hysteresis causes some of the heat energy to be lost, but this new alloy has a low hysteresis, the researchers say. Because of this, it could be used to convert waste heat energy into large amounts of electricity.

One obvious use for this material would be in the exhaust pipes of vehicles. Several automakers are already working on heat transfer devices that can convert a car’s hot exhaust into usable electricity; General Motors is using alloys called skutterudites, which are cobalt-arsenide materials doped with rare earths.

Rare earth magnets are already a necessity in many hybrid car batteries, so heat-capture devices made of the new multiferroic compound could be placed near the magnets.
The material could also be used in power plants or even ocean thermal energy generators, the researchers said.

A paper on the alloy was published in the journal Advanced Energy Materials.

This technology would also have very obvious applications in solar power Eegeneration.

Or really any kind of power generation. I'm looking to see if it could be useful in nuclear (fission, or preferably fusion) power generation applications, since it could potentially drastically cut down on reactor size, especially if it is more efficient than water-based systems employed now. Of course, since it probably won't cool the reactor as fast as a water based system would then fuel load may have to be made smaller at the same time, but if at the end we get a cheaper reactor that's for the better, I think. And the smaller fuel load would mean that a nuclear accident would be easier to prevent, especially if the reactor is designed to run without active cooling.

Or really any kind of power generation.

Don't use it for cooling the reactor. Rather, use it to cool the water after it leaves the steam turbines. That way you get both the power generated from the turbines and extra while doing away with the massive cooling towers.

Don't use it for cooling the reactor. Rather, use it to cool the water after it leaves the steam turbines. That way you get both the power generated from the turbines and extra while doing away with the massive cooling towers.

So what is the conversion efficiency of this process versus the carnot, brayton or even stirling cycle?

Do we have enough of the rarer bits of metal to cover any significant area with the stuff? Also, the US can't even keep bridges from collapsing, let alone even dream of resurfacing even a fraction of the total road system even in just the southern most 10% of the nation.

Look, you take grids of this shit, and just pound it the hell into the pavement/sidewalks, then a quick splash of asphault and bob's your uncle. you don't have to do it all at once, and you don't have to do it for all the roads, just the ones in the urban areas for now. The earth sucks up enough heat every day from the sun that it seems foolish to *not* mine it in some form. You doul even just run freaking pipes under the ground filled with ammonia or some other liquid with an absurdly low boiling point, circulate it through the pipes, back to a radiator made of that shit to harvest the heat/make electricity, then you just let the condensed liquid flow back to continue the loop.

I think someone needs to inject some reality into this discussion.

Firstly, this thing has zero application in a nuclear reactor. For starters, this alloy "works" by oscillating its temperature about some point, so that you get that magnetic switching effect. In other words, the alloy itself has to be cooled, since once you heat it up past the magnetic threshold, you need to cool it down past that threshold in order to heat it up again (unless I'm totally missing something here).

Secondly, you can't put a nickel alloy into a nuclear reactor - end of story. Nickel, compared to other metals, is extremely prone to neutron radiation damage. Statistically, a nickel material in a thermal fission reactor would experience at least one dislocation of every single nickel atom in the material every six months, due to neutron interactions (a dislocation is when the atom is ejected from its position in the crystal lattice of the metal). This leads to a bunch of material degradation phenomena, like creep (along all axis), large loss in ductility, large decrease in yield strength, large increase in the temperature dependency of yield strength, accelerated fatigue crack growth, etc. Nickel just isn't used in these cores.

So, this thing must work in pulses. Heated to above its "trick temp" and generates a jolt of power, then cooled to below its trick temp and returns inert. Rinse and repeat.