7 comments on “Thermoelectrics

  1. I loooooooooove it! Thanks for this post! I hope there is more to come!

    Oh! Oh! tell people about the thermal electric materials on spaceships!

    bumped into my twitter feed!

  2. Well, consider me subscribed. Hope it goes well. I’ll try not to pull holes in every single thing. Who’s the blog really for though, Laurie? Other researchers? random Guardian readers? If you work that out it will make the writing a bit easier.

  3. But I couldn’t resist. What’s this “wasted”? Aren’t all thermodynamic systems going to have some waste heat, as in not converted to mechanical work? But you seem to be connoting wasted as in (Lean, Toyota etc ) Muda (無駄) : resource not fully utilised in an economic sense.

  4. Its more for me at the moment. I’m just using it as a place to collect all my non-work/PhD writing.

    The “Life etc.” posts are pulled from my journal.

    The science-y articles are pitched at a general (non-technical) audience – both of the current ones will be appearing on a website near you soon, albeit not in their current form.

    I’ll write even if no-one reads it…. thanks for subscribing tho 🙂

  5. Yes, of course there will always be wasted heat. But upwards of 60% is excessive in anyone’s language! I mean that you put fuel in, and of the energy that fuel can offer, only ~40% goes towards moving the car forward, operating the brakes etc. TE materials can capture a small percentage of this and use it to recharge a battery for example – in fact, we’re involved in large European project to do just that. NPL’s emphasis is on the characterisation of the materials themselves.

  6. Hi Laurie.

    I have thought about this a few times and if I have understood this correctly, I think that solar cells and thermoelectric devices shouldn’t really be compared like this.

    Solar cells, like fuel cells, are energy conversion devices and can in principle be 100% efficient. The second law of thermodynamics places no limit on their efficiency.

    Thermoelectric devices are heat engines: they derive some useful work from a heat flow across a temperature drop. Their efficiency is fundamentally limited by the second law of thermodynamics. For a temperature difference of 100 °C this limits the possible conversion efficiency to 27% ish before one even begins to worry about how to make the devices work. Actually 7% sounds pretty good to me.

    However I do look forward to new super duper materials which push the laws of thermodynamics to their limit!

    M

  7. Hi Michael 🙂 It was more to give an idea of how much more work we still need to do to make them viable – we’ve “only” managed to reach 7% efficiencies and we’ve known about the Seebeck effect since the 1800’s. Solar cells are comparatively new and yet we’ve managed to massively improve on their operating efficiencies. But yes, you’re absolutely right (of course!) they certainly should not be directly compared, as they are entirely different technologies.

    7% is indeed pretty impressive, but we also have a big problem with cost and availability – Tellurium, the element that is used in the most efficient TE generators is the rarest stable solid elements in the Earth’s crust. So there are two parallel efforts to broach this:
    1. We’re looking at a number of alternative materials, such as skutterudites, bismuth selenide and some oxides
    2. Making the tellurium based materials more efficient, to get the full “worth” from their high cost, e.g. nanostructuring the materials to improve the figure of merit.

    So we’ve a lot to do!

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