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This device doesn't really change the energy landscape. Let's rephrase the title: "A new heat engine is as efficient as a steam engine but needs a thermal sourc

This device doesn't really change the energy landscape. Let's rephrase the title: "A new heat engine is as efficient as a steam engine but needs a thermal source 1,800 degrees celsius hotter to work". The device described in the article is interesting in that it has no moving parts and might have an application one something like a nuclear powered spacecraft. Actually trying to harvest energy from TEGs is exceptionally difficult, since renewable energy sources aren't nearly as energy dense as thermal fuels like hydrocarbons or fission. The thermal gradients produced through renewable sources like solar are tiny [1]. It could be used for something like geothermal power, but again it needs temperatures way hotter than conventional steam engines which already work fine for geothermal energy production. 1. https://www.youtube.com/watch?v=Tdge8vEODeY https://www.youtube.com/watch?v=Tdge8vEODeY

jvanderbot 5y ago
This is an absolute game changer for planetary exploration, where RTGs are common.
- xyzzyz 5y ago
  RTGs do not get anywhere close to 1800 degrees Celsius. Even if they did, it wouldn’t be a game changer, because you can make up for loss of efficiency with a bigger RTG.
  - jvanderbot 5y ago
    OK, perhaps I stand corrected (or just tempered).
zdkl 5y ago
Re. thermal gradients, have you considered plain old mirrors? https://en.wikipedia.org/wiki/Odeillo_solar_furnace https://en.wikipedia.org/wiki/Odeillo_solar_furnace > 54 metres (177 ft) high and 48 metres (157 ft) wide > more than 2,500 h/year [sunlight] > peak power of 3200 kW > Temperatures above 2,500 °C (4,530 °F) Sounds like it could be useful as a "default load" inside an otherwise inactive solar furnace at least.
- Manuel_D 5y ago
  You're describing solar thermal energy [1]. Use solar collectors to turn light into heat, then use a heat engine to turn that heat into electricity. This TEG could be used as a heat engine for this task. But again, our heat engines are already capable of this task and don't need such high temperatures. A solar collector array even getting to this TEG's operating temperature might not be feasible. Photovoltaics just turn solar energy into electricity, and don't need the heat engine. This has made them way cheaper to deploy than solar thermal energy. So unless there's something very important about this new TEG, the solar thermal vs photovoltaic calculus doesn't really change. 1. https://en.wikipedia.org/wiki/Solar_thermal_energy https://en.wikipedia.org/wiki/Solar_thermal_energy
  - guelo 5y ago
    The point is to store the thermal energy for later use to smoothen out photovoltaic's intermittency issues.
    - Manuel_D 5y ago
      Right. But we already have that technology with conventional heat engines which have the advantage of much, much, lower operating temperature requirements. If you have a 3,000 degree vat of thermal storage material this new engine stops working after draining 1000 degrees. Existing heat engines can usually work down to several hundred Celsius - though superheated steam engines need around 700 Celsius. But that's still an extra 1000 degrees you can bring it down, even in the conservative case.
      - gibolt 5y ago
        This is the first of its kind to reach this efficiency, correct? I assume that means there could be room to significantly improve its efficiency or operating requirements with more investment and research. Having one example, even if 'useless' or elementary, is key to developing new technology.
        5y ago
samatman 5y ago
> "A new heat engine is as efficient as a steam engine but needs a thermal source 1,800 degrees celsius hotter to work" But this title would not be correct. Methane combusts at 1,957 °C, right in the band for this thermal cell, and is a normal heat source for steam power. The steam doesn't reach this temperature, of course, but nor does it need to.

jvanderbot 5y ago

This is an absolute game changer for planetary exploration, where RTGs are common.

xyzzyz 5y ago
RTGs do not get anywhere close to 1800 degrees Celsius. Even if they did, it wouldn’t be a game changer, because you can make up for loss of efficiency with a bigger RTG.
- jvanderbot 5y ago
  OK, perhaps I stand corrected (or just tempered).

zdkl 5y ago

Re. thermal gradients, have you considered plain old mirrors? https://en.wikipedia.org/wiki/Odeillo_solar_furnace https://en.wikipedia.org/wiki/Odeillo_solar_furnace > 54 metres (177 ft) high and 48 metres (157 ft) wide > more than 2,500 h/year [sunlight] > peak power of 3200 kW > Temperatures above 2,500 °C (4,530 °F) Sounds like it could be useful as a "default load" inside an otherwise inactive solar furnace at least.

Manuel_D 5y ago
You're describing solar thermal energy [1]. Use solar collectors to turn light into heat, then use a heat engine to turn that heat into electricity. This TEG could be used as a heat engine for this task. But again, our heat engines are already capable of this task and don't need such high temperatures. A solar collector array even getting to this TEG's operating temperature might not be feasible. Photovoltaics just turn solar energy into electricity, and don't need the heat engine. This has made them way cheaper to deploy than solar thermal energy. So unless there's something very important about this new TEG, the solar thermal vs photovoltaic calculus doesn't really change. 1. https://en.wikipedia.org/wiki/Solar_thermal_energy https://en.wikipedia.org/wiki/Solar_thermal_energy
- guelo 5y ago
  The point is to store the thermal energy for later use to smoothen out photovoltaic's intermittency issues.
  - Manuel_D 5y ago
    Right. But we already have that technology with conventional heat engines which have the advantage of much, much, lower operating temperature requirements. If you have a 3,000 degree vat of thermal storage material this new engine stops working after draining 1000 degrees. Existing heat engines can usually work down to several hundred Celsius - though superheated steam engines need around 700 Celsius. But that's still an extra 1000 degrees you can bring it down, even in the conservative case.
    - gibolt 5y ago
      This is the first of its kind to reach this efficiency, correct? I assume that means there could be room to significantly improve its efficiency or operating requirements with more investment and research. Having one example, even if 'useless' or elementary, is key to developing new technology.
      - 5y ago

samatman 5y ago

> "A new heat engine is as efficient as a steam engine but needs a thermal source 1,800 degrees celsius hotter to work" But this title would not be correct. Methane combusts at 1,957 °C, right in the band for this thermal cell, and is a normal heat source for steam power. The steam doesn't reach this temperature, of course, but nor does it need to.