New alloy converts heat directly to electricity

[auroraglacialis]

Generating 'green' electricity: Waste heat converted to electricity using new alloy

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.

This could be used to get electricity from waste heat or smallscale solar dishes. Pretty neat. Sadly it is "Ni45Co5Mn40Sn10", so it uses quite a lot of Cobalt in addition to Nickel - not yet a problem in respect to resource depletion, but certainly one in terms of environmental and humanitarian impact as major producers are African countries with inadequate protection regulations. Cobalt is a rather rare element, which means a lot of material has to be processed to extract it (=vast open pit mines consuming a lot of energy) and the extraction and processing is not exactly eco-friendly or healthy for the workers. Cobalt and nickel reserves however are said to last for some more decades.

[ISV Venture Star]

Nice! This could also conceivably be used to improve the efficiency of radioisotope power devices on interplanetary spacecraft.

[Advent]

In low heat environments however, this material would be far less efficient, if not useless, am I not mistaken?

[auroraglacialis]

As I understand it, the material uses slight changes in temperature above and below a fixed temperature point to generate electricity. The operating range is thus very limited to a specific temperature. If the material can be created to have this temperature at the lower end of it, I do not know, but it is imaginable.

[Advent]

Hmm. Curious.

If it can only produce electricity at specific temperatures, then it may become nothing less then other power sources which require such heat, or byproducts of it. Here's to hoping it may become an efficient, versatile power source.

[Human No More]

It's certainly interesting, and hopefully even useful , but you have to wonder exactly what is needed to manufacture it, and indeed, whether it will work on a macroscopic scale or not.

[auroraglacialis]

Well it needs not just one constant temperature but rather slightly oscillating temperatures. And yes of course it needs as all other thermal power sources - a heat source and a cold reservoir. If it is better than a regular heat engine remains to be seen, they do mention that they see quite some loss.
Regarding manufacturing, I am worried that it seems to take a lot of metals, especially "rare" ones (not rare in terms of availability but rare in terms of concentrations in ores). These are very toxic to produce usually. I still remember that toxic lake several miles long in China that is there now because of the industrialized worlds demand of neodymium for windmills. And that is the problem with doing any such thing on a large, macroscopic scale. It sounds all fine for some small scale applications, but once you start to need millions of tons of material....

[Sight Unseen]

From what I'm reading, this would be somewhat complex to use commercially. The temperature would have to be raised and lowered repeatedly and rapidly for it to be effective. Just heating it up and letting it cool off naturally wouldn't be effective, unless you have a *lot* of these, and an equally large amount of capacitors, and there goes your efficiency... something tells me this isn't really feasible.

An interesting material, but how exactly does this benefit anyone? Methinks it will ultimately be too inefficient to use effectively, and due to the quantities of rare elements needed, along with the aforementioned environmental impact and working conditions, would ultimately be a bad idea to pursue.

[auroraglacialis]

Well the metal would indeed have to be rapidly heated and cooled. But that is not impossible - it could get streams of warm exhaust gasses in turn with colder atmospheric air. After all, combustion engines also rely on a cyclical change. Not impossible but still I am also suspicious that it will be really that efficient as the inventors hope it to be

[mikkowilson]

Sounds pretty similar to a thermocouple.

- Mikko

[applejuice]

Originally Posted by Sight Unseen

From what I'm reading, this would be somewhat complex to use commercially. The temperature would have to be raised and lowered repeatedly and rapidly for it to be effective. Just heating it up and letting it cool off naturally wouldn't be effective, unless you have a *lot* of these, and an equally large amount of capacitors, and there goes your efficiency... something tells me this isn't really feasible.

An interesting material, but how exactly does this benefit anyone? Methinks it will ultimately be too inefficient to use effectively, and due to the quantities of rare elements needed, along with the aforementioned environmental impact and working conditions, would ultimately be a bad idea to pursue.

You're right. The article says that it generates electricity in a surrounding coil. To induce a potential difference in a coil, the magnetic field must be variable in time (it's called Faraday's Law). Then, the material needs to be cooled and heated through time to change the magnetization of the material. A constant temperature differential won't generate any electricity, in this case, you will have just a magnet.

Originally Posted by mikkowilson

Sounds pretty similar to a thermocouple.

- Mikko

A thermocouple does not need a variable temperature to produce a potential differential. A thermocouple produces a voltage that is proportional to the temperature difference between the junctions. Though, it only produces voltages in the order of millivolts or microvolts.