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0 comments after 20 minutes on an energy post? How am I supposed to know why this won't work, won't be useful, won't be cost effective, won't scale, and that it

0 comments after 20 minutes on an energy post? How am I supposed to know why this won't work, won't be useful, won't be cost effective, won't scale, and that it's just a fad? Jokes aside, this seems impressive, I have no idea what the best applications would be but wikipedia claims that current similar devices have fairly bad efficiency(https://en.wikipedia.org/wiki/Thermoelectric_generator https://en.wikipedia.org/wiki/Thermoelectric_generator).

smrtinsert 5y ago
Exactly why I clicked in, but man this technology sounds like a serious gamechanger.
willhinsa 5y ago
Thanks for the laugh! So true.
yetihehe 5y ago
> won't be useful, won't be cost effective > The team’s design can generate electricity from a heat source of between 1,900 to 2,400 degrees Celsius Pretty high temperature for me, copper melts at 1800C.
- wishawa 5y ago
  High temperature is the point. The efficiency of heat engines depend on the temperature difference (relative to ambient). The hotter you can go, the better. (granted this thing isn’t really an “engine”, but the trend still applies)
  - dv_dt 5y ago
    But for practical applications, the availability and cost of materials to survive the operating temperature is also relevant.
- diarrhea 5y ago
  A Carnot heat engine operating between, say, 2600K and 400K can reach almost 85% efficiency. The higher the temperature, the higher the share of exergy in the heat flux. At high enough temperatures, it’s no longer a feat to convert to electricity at high efficiencies.
  - rowanG077 5y ago
    It would be pretty hard to create a carnot heat engine that can withstand 2600k. I'm not even sure if for example Tungsten has structurally integrity at that point.
- giantg2 5y ago
  That might be when copper liquifies. It will lose its structural integrity and deform easily at much lower temperatures.
- justinlloyd 5y ago
  Pfff! Amateur! You should try pulling the plug out of the tub when its filled with my wife's bathwater.
marcosdumay 5y ago
This is not similar to anything on that page, as it operates on temperatures of thousands of degrees. The comparison with steam engines is also quite bad, as the Carnot efficiency on that kind of temperature difference is way above 90%. So, it's just an overrating research PR piece, like the ones people like to complain. This thing probably scales just fine, and may be quite useful. The entire problem is that science gets divulged on those insane PR pieces where it's compared to completely different things, or promise completely impossible results.
- abeppu 5y ago
  > the Carnot efficiency on that kind of temperature difference is way above 90%. This is definitely not my area, but is Carnot efficiency directly comparable to the efficiency numbers cited in the article? Or is the "work" in Carnot efficiency the mechanical work, prior to being converted to electricity?
  - kragen 5y ago
    Yes, it's directly comparable. You can interconvert mechanical work and electricity freely; electricity isn't like heat. Everyday machinery does it with 95% efficiency, but there's no fundamental limit.
- diarrhea 5y ago
  At those temperatures, Carnot efficiency is between 80 and 90 percent. The comparison to steam engines is misleading, but there’s an important distinction. Steam or gas turbines would reach very high efficiencies at these temperatures too, but won’t because of material properties and limitations thereof. These limitations don’t seem to exist for this new technology. Hence, reaching very high efficiencies becomes possible. In theory… In practice, I don’t see how heat sources with temperatures that high are feasible or could stem from renewable sources. (something with the thermal battery? Wasn’t explained much in the article) In any case, in comparison to steam turbines, the technology presented here does absolutely nothing in terms of decarbonising the grid, as claimed. It’s just potentially more efficient. But what’s the source for the primary energy?
javajosh 5y ago
>why this won't work, won't be useful, won't be cost effective, won't scale Not an expert, but reading this a few negatives popped out. Basically they are heating a black body to 2400C and then making electricity from gathering the emitted light in a cell. They get to pick a temperature to match the bandgap of the cell. The key problem is getting something that hot without using another (lossy) form of power. The Sun's surface is ~5600C so that's enough headroom to get there from solar. That's cool. But are there any fission reactors that get (or could get) that ridiculously hot?
- giantg2 5y ago
  Chernobyl did. I think most try to keep temperatures under 1000C. I think many FAST reactor designs are looking at 600C operating temps with peak temp reaching maybe 1200C during emergency testing. But my memory might be wrong.
- sandworm101 5y ago
  Biggest key problem imho is how they expect to store this heat energy. It looks like this cell will, like a PV cell, constantly be absorbing photons. If those photons aren't creating electricity/voltage across a gap then they are being converted into heat. So to keep the medium at temperature you would need to insulate it, to wrap it in a mirror, only exposing the flux to the energy-collecting cell as needed. That means moving parts. As for available temperatures from fission reactors: https://en.wikipedia.org/wiki/NERVA https://en.wikipedia.org/wiki/NERVA "When the reactor was operating at full power, about 1,140 MW, the chamber temperature was 2,272 K (2,000 °C)"
  - thehappypm 5y ago
    This is a bummer, but probably a reality. Perhaps some kind of LCD type tech could make for it to be more digital/less big metal moving around.
- Animats 5y ago
  "The team’s design can generate electricity from a heat source of between 1,900 to 2,400 degrees Celsius" That's way up there. That's well above the melting point of steel. That's above the highest temperature jet engines made for experimental aircraft.[1] Most jet engines try for exhaust gas temperatures around 600C or so, for a long useful life. Typical nuclear reactors, around 300C. It's not impossible to operate up at those temperatures. Every steel plant does it. There are ceramic and brick materials that can deal with such temperatures.[2] The storage medium would probably be some molten metal. This seems way too much trouble just to store energy. Now if this thing worked at 600C or so, there would be more uses. [1] https://www.nasa.gov/centers/dryden/pdf/88068main_H-1375.pdf https://www.nasa.gov/centers/dryden/pdf/88068main_H-1375.pdf [2] https://www.ceramicsrefractories.saint-gobain.com/refractory-solutions/steelmaking/steel-ladle https://www.ceramicsrefractories.saint-gobain.com/refractory...
GoodJokes 5y ago
pvarangot 5y ago
No news is good news, this one probably will work I guess.
DontGiveTwoFlux 5y ago
Not mentioned in the article is power density. How quickly can the energy be released? Consider solar panels, you need a table sized cell to get 100W. That can make for a big battery to get grid scale power output if these cells are only as power dense as solar panels. The energy density of a heat based solution can be very high- metals can get very hot and they are dense enough to store a lot of energy. But if you can’t get the energy out of the battery fast enough that limits the applications. By comparison lithium ion batteries can dump power out extremely quickly, which is what makes them great for cars. Hydro is even better.
- Retric 5y ago
  Surface area is relevant for solar because the sun is so far away. A local heat source allows you to surround it with 3D shapes not just a flat plain. As to temperature this thing is for very high temperatures: can generate electricity from a heat source of between 1,900 to 2,400 degrees Celsius. At 40% efficient you need a wide temperature difference which would suggest a high energy density.
  - ethbr0 5y ago
    For long term energy banking and if we can get them working, flow batteries seem vastly superior to all alternatives, by scaling storage with regards to tank volume. Instead of some difficult-to-manufacture structure.
  - walnutclosefarm 5y ago
    This design is photovoltaics, just like solar, but optimized for infrared photons. There is no avoiding the reality that energy storage density will scale as the cube of the facility size, but power density only as the square. And at 2.38 w/cm^2, the scale coefficient is not all that great.
    - Retric 5y ago
      Picture a stack of flat panels with each layer consisting of: (Cold)(Panel)(Hot)(Panel)(Cold) held vertically. So: (Cold)(Panel)(Hot)(Panel)(Cold)(Panel)(Hot)(Panel)(Cold)(Panel)(Hot) Now you add hot gas at the bottom and have say 4 layers per m. So a 3mx3mx3m cube would be 4 layers * 2 panels per layer * 3m * 3m * 3m = 216m2 of panels taking up a 3mx3m section of floor. At 2.38w/cm2 * 10000cm2/m2 * 216m2 = 5.14 MW of power.
Manuel_D 5y ago
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.

smrtinsert 5y ago

Exactly why I clicked in, but man this technology sounds like a serious gamechanger.

willhinsa 5y ago

Thanks for the laugh! So true.

yetihehe 5y ago

> won't be useful, won't be cost effective > The team’s design can generate electricity from a heat source of between 1,900 to 2,400 degrees Celsius Pretty high temperature for me, copper melts at 1800C.

wishawa 5y ago
High temperature is the point. The efficiency of heat engines depend on the temperature difference (relative to ambient). The hotter you can go, the better. (granted this thing isn’t really an “engine”, but the trend still applies)
- dv_dt 5y ago
  But for practical applications, the availability and cost of materials to survive the operating temperature is also relevant.
diarrhea 5y ago
A Carnot heat engine operating between, say, 2600K and 400K can reach almost 85% efficiency. The higher the temperature, the higher the share of exergy in the heat flux. At high enough temperatures, it’s no longer a feat to convert to electricity at high efficiencies.
- rowanG077 5y ago
  It would be pretty hard to create a carnot heat engine that can withstand 2600k. I'm not even sure if for example Tungsten has structurally integrity at that point.
giantg2 5y ago
That might be when copper liquifies. It will lose its structural integrity and deform easily at much lower temperatures.
justinlloyd 5y ago
Pfff! Amateur! You should try pulling the plug out of the tub when its filled with my wife's bathwater.

marcosdumay 5y ago

This is not similar to anything on that page, as it operates on temperatures of thousands of degrees. The comparison with steam engines is also quite bad, as the Carnot efficiency on that kind of temperature difference is way above 90%. So, it's just an overrating research PR piece, like the ones people like to complain. This thing probably scales just fine, and may be quite useful. The entire problem is that science gets divulged on those insane PR pieces where it's compared to completely different things, or promise completely impossible results.

abeppu 5y ago
> the Carnot efficiency on that kind of temperature difference is way above 90%. This is definitely not my area, but is Carnot efficiency directly comparable to the efficiency numbers cited in the article? Or is the "work" in Carnot efficiency the mechanical work, prior to being converted to electricity?
- kragen 5y ago
  Yes, it's directly comparable. You can interconvert mechanical work and electricity freely; electricity isn't like heat. Everyday machinery does it with 95% efficiency, but there's no fundamental limit.
diarrhea 5y ago
At those temperatures, Carnot efficiency is between 80 and 90 percent. The comparison to steam engines is misleading, but there’s an important distinction. Steam or gas turbines would reach very high efficiencies at these temperatures too, but won’t because of material properties and limitations thereof. These limitations don’t seem to exist for this new technology. Hence, reaching very high efficiencies becomes possible. In theory… In practice, I don’t see how heat sources with temperatures that high are feasible or could stem from renewable sources. (something with the thermal battery? Wasn’t explained much in the article) In any case, in comparison to steam turbines, the technology presented here does absolutely nothing in terms of decarbonising the grid, as claimed. It’s just potentially more efficient. But what’s the source for the primary energy?

javajosh 5y ago

>why this won't work, won't be useful, won't be cost effective, won't scale Not an expert, but reading this a few negatives popped out. Basically they are heating a black body to 2400C and then making electricity from gathering the emitted light in a cell. They get to pick a temperature to match the bandgap of the cell. The key problem is getting something that hot without using another (lossy) form of power. The Sun's surface is ~5600C so that's enough headroom to get there from solar. That's cool. But are there any fission reactors that get (or could get) that ridiculously hot?

giantg2 5y ago
Chernobyl did. I think most try to keep temperatures under 1000C. I think many FAST reactor designs are looking at 600C operating temps with peak temp reaching maybe 1200C during emergency testing. But my memory might be wrong.
sandworm101 5y ago
Biggest key problem imho is how they expect to store this heat energy. It looks like this cell will, like a PV cell, constantly be absorbing photons. If those photons aren't creating electricity/voltage across a gap then they are being converted into heat. So to keep the medium at temperature you would need to insulate it, to wrap it in a mirror, only exposing the flux to the energy-collecting cell as needed. That means moving parts. As for available temperatures from fission reactors: https://en.wikipedia.org/wiki/NERVA https://en.wikipedia.org/wiki/NERVA "When the reactor was operating at full power, about 1,140 MW, the chamber temperature was 2,272 K (2,000 °C)"
- thehappypm 5y ago
  This is a bummer, but probably a reality. Perhaps some kind of LCD type tech could make for it to be more digital/less big metal moving around.
Animats 5y ago
"The team’s design can generate electricity from a heat source of between 1,900 to 2,400 degrees Celsius" That's way up there. That's well above the melting point of steel. That's above the highest temperature jet engines made for experimental aircraft.[1] Most jet engines try for exhaust gas temperatures around 600C or so, for a long useful life. Typical nuclear reactors, around 300C. It's not impossible to operate up at those temperatures. Every steel plant does it. There are ceramic and brick materials that can deal with such temperatures.[2] The storage medium would probably be some molten metal. This seems way too much trouble just to store energy. Now if this thing worked at 600C or so, there would be more uses. [1] https://www.nasa.gov/centers/dryden/pdf/88068main_H-1375.pdf https://www.nasa.gov/centers/dryden/pdf/88068main_H-1375.pdf [2] https://www.ceramicsrefractories.saint-gobain.com/refractory-solutions/steelmaking/steel-ladle https://www.ceramicsrefractories.saint-gobain.com/refractory...

GoodJokes 5y ago

pvarangot 5y ago

No news is good news, this one probably will work I guess.

DontGiveTwoFlux 5y ago

Not mentioned in the article is power density. How quickly can the energy be released? Consider solar panels, you need a table sized cell to get 100W. That can make for a big battery to get grid scale power output if these cells are only as power dense as solar panels. The energy density of a heat based solution can be very high- metals can get very hot and they are dense enough to store a lot of energy. But if you can’t get the energy out of the battery fast enough that limits the applications. By comparison lithium ion batteries can dump power out extremely quickly, which is what makes them great for cars. Hydro is even better.

Retric 5y ago
Surface area is relevant for solar because the sun is so far away. A local heat source allows you to surround it with 3D shapes not just a flat plain. As to temperature this thing is for very high temperatures: can generate electricity from a heat source of between 1,900 to 2,400 degrees Celsius. At 40% efficient you need a wide temperature difference which would suggest a high energy density.
- ethbr0 5y ago
  For long term energy banking and if we can get them working, flow batteries seem vastly superior to all alternatives, by scaling storage with regards to tank volume. Instead of some difficult-to-manufacture structure.
- walnutclosefarm 5y ago
  This design is photovoltaics, just like solar, but optimized for infrared photons. There is no avoiding the reality that energy storage density will scale as the cube of the facility size, but power density only as the square. And at 2.38 w/cm^2, the scale coefficient is not all that great.
  - Retric 5y ago
    Picture a stack of flat panels with each layer consisting of: (Cold)(Panel)(Hot)(Panel)(Cold) held vertically. So: (Cold)(Panel)(Hot)(Panel)(Cold)(Panel)(Hot)(Panel)(Cold)(Panel)(Hot) Now you add hot gas at the bottom and have say 4 layers per m. So a 3mx3mx3m cube would be 4 layers * 2 panels per layer * 3m * 3m * 3m = 216m2 of panels taking up a 3mx3m section of floor. At 2.38w/cm2 * 10000cm2/m2 * 216m2 = 5.14 MW of power.

Manuel_D 5y ago

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.