5 ms·

SOHCs are approaching 100% conversion efficiency, and SOFCs have 60% baseline efficiency, and with practical heat conversion technologies, have closer to 75% ef

SOHCs are approaching 100% conversion efficiency, and SOFCs have 60% baseline efficiency, and with practical heat conversion technologies, have closer to 75% efficiency. And they can use hydrocarbon fuels which can open up fuel options to synthetic fuels that have more reasonable mass/volume tradeoffs.

SigmundA 5y ago
Heat conversion is going to mean more equipment (heat recovery turbine?). SOHCS run at what 1000c? Don't see that being practical for vehicle use any time soon.
- darksaints 5y ago
  Heat recovery turbines are awesome. A single moving part, that's it. And those temperatures are not a problem at all. Standard off-the-shelf calcium silicate insulation will work fine.
  - SigmundA 5y ago
    Single moving part and generator and power control. None of that is free in terms of complexity, weight and cost. This is on top of whats needed for the fuel cell, plus you will probably need a buffer battery to fully utilize. Makes more sense to look at heat recovery turbines for a diesel engine which is exactly what Freightliner is doing with their Supertruck bringing its thermal efficiency up around 60%.
    - darksaints 5y ago
      It makes less sense on a diesel engine because their heat sources are lower temp. Fuel cells produce much more useful heat for a heat engine to capture. And no, the complexity of heat recovery isn't high at all. The costs pay themselves off almost immediately. They're orders of magnitude less complex than an ICE, last almost forever, and require almost no maintenance apart from cleaning after tens of thousands of hours. If a modern heat recovery turbine is too complex, then so is an electric motor.
      - SigmundA 5y ago
        Diesel exhaust temps are around 600c SOFC operate 600c-1000c. Heat recovery turbines use either organic Rankine cycle (steam turbine) or Brayton where the fuel cell replaces or is along side the combustion chamber in a gas turbine. Comparing the complexity of a Heat recovery turbine to an electric motor is absurd. Let me know when a SOFC with recovery turbine is in a truck.
        darksaints 5y ago
        It's a turbine. It spins inside a housing. It has an input and an output. Modern turbines don't even have oil...they use ceramic air bearings that might need to be replaced sometime after you die.
        SigmundA 5y ago
        A turbine does nothing by itself again an absurd statement. A heat recovery turbine has a host of support systems to actually recover heat including a generator which is essentially an electric motor to capture electrical energy. I don't see a lot of gas turbines in various use around me, and the ones that are are quite expensive to fix. I do however see electric motors everywhere and they are extremely reliable and cheap.
        darksaints 5y ago
        Lol, there is no need to speculate about the practicality of heat recovery turbines in vehicles. They're already in use by millions of cars and trucks. Nearly every semi truck on the road has one...sometimes they have two! They're called turbochargers. More specifically, the heat recovery turbine is the exhaust-connected half of the turbocharger. Most car turbos drive air compressors to increase ICE efficiency (surplus electric power isn't so useful for ICE cars), but you can literally chop the turbocharger in half and attach an electric motor to the turbine shaft, and voila, now you have an electric heat recovery turbine. Were you actually thinking I was proposing attaching a steam turbine to a fuel cell? Lol. Can I subscribe to the Cult of Elon's Version of Facts? This is hilarious.
seryoiupfurds 5y ago
So SOFC seems to be a solid oxide fuel cell[0], but despite the automotive context I don't think SOHC means single overhead camshaft here. [0]: https://en.wikipedia.org/wiki/Solid_oxide_fuel_cell https://en.wikipedia.org/wiki/Solid_oxide_fuel_cell
- darksaints 5y ago
  Sorry, meant SOEC. Meant for converting water + electricity into hydrogen. https://en.wikipedia.org/wiki/Solid_oxide_electrolyzer_cell https://en.wikipedia.org/wiki/Solid_oxide_electrolyzer_cell High temperature operation is what allows it to have such high conversion efficiency. http://www.helmeth.eu/index.php/technologies/high-temperature-electrolysis-cell-soec http://www.helmeth.eu/index.php/technologies/high-temperatur...

SigmundA 5y ago

Heat conversion is going to mean more equipment (heat recovery turbine?). SOHCS run at what 1000c? Don't see that being practical for vehicle use any time soon.

darksaints 5y ago
Heat recovery turbines are awesome. A single moving part, that's it. And those temperatures are not a problem at all. Standard off-the-shelf calcium silicate insulation will work fine.
- SigmundA 5y ago
  Single moving part and generator and power control. None of that is free in terms of complexity, weight and cost. This is on top of whats needed for the fuel cell, plus you will probably need a buffer battery to fully utilize. Makes more sense to look at heat recovery turbines for a diesel engine which is exactly what Freightliner is doing with their Supertruck bringing its thermal efficiency up around 60%.
  - darksaints 5y ago
    It makes less sense on a diesel engine because their heat sources are lower temp. Fuel cells produce much more useful heat for a heat engine to capture. And no, the complexity of heat recovery isn't high at all. The costs pay themselves off almost immediately. They're orders of magnitude less complex than an ICE, last almost forever, and require almost no maintenance apart from cleaning after tens of thousands of hours. If a modern heat recovery turbine is too complex, then so is an electric motor.
    - SigmundA 5y ago
      Diesel exhaust temps are around 600c SOFC operate 600c-1000c. Heat recovery turbines use either organic Rankine cycle (steam turbine) or Brayton where the fuel cell replaces or is along side the combustion chamber in a gas turbine. Comparing the complexity of a Heat recovery turbine to an electric motor is absurd. Let me know when a SOFC with recovery turbine is in a truck.
      - darksaints 5y ago
        It's a turbine. It spins inside a housing. It has an input and an output. Modern turbines don't even have oil...they use ceramic air bearings that might need to be replaced sometime after you die.
        SigmundA 5y ago
        A turbine does nothing by itself again an absurd statement. A heat recovery turbine has a host of support systems to actually recover heat including a generator which is essentially an electric motor to capture electrical energy. I don't see a lot of gas turbines in various use around me, and the ones that are are quite expensive to fix. I do however see electric motors everywhere and they are extremely reliable and cheap.
        darksaints 5y ago
        Lol, there is no need to speculate about the practicality of heat recovery turbines in vehicles. They're already in use by millions of cars and trucks. Nearly every semi truck on the road has one...sometimes they have two! They're called turbochargers. More specifically, the heat recovery turbine is the exhaust-connected half of the turbocharger. Most car turbos drive air compressors to increase ICE efficiency (surplus electric power isn't so useful for ICE cars), but you can literally chop the turbocharger in half and attach an electric motor to the turbine shaft, and voila, now you have an electric heat recovery turbine. Were you actually thinking I was proposing attaching a steam turbine to a fuel cell? Lol. Can I subscribe to the Cult of Elon's Version of Facts? This is hilarious.

seryoiupfurds 5y ago

So SOFC seems to be a solid oxide fuel cell[0], but despite the automotive context I don't think SOHC means single overhead camshaft here. [0]: https://en.wikipedia.org/wiki/Solid_oxide_fuel_cell https://en.wikipedia.org/wiki/Solid_oxide_fuel_cell

darksaints 5y ago
Sorry, meant SOEC. Meant for converting water + electricity into hydrogen. https://en.wikipedia.org/wiki/Solid_oxide_electrolyzer_cell https://en.wikipedia.org/wiki/Solid_oxide_electrolyzer_cell High temperature operation is what allows it to have such high conversion efficiency. http://www.helmeth.eu/index.php/technologies/high-temperature-electrolysis-cell-soec http://www.helmeth.eu/index.php/technologies/high-temperatur...