4 ms·

I hear a lot about replacing gas with hydrogen (completely doable with the existing infrastructure).

unpolloloco 5y ago
Which is effectively a battery! Hydrogen production is energy intensive, but if you produce it with excess energy capacity and then use it when it's needed, it's a decent energy storage method. Though mobile applications (air travel, trains, etc) are more likely to dominate in the shorter terms as it's lighter than batteries in high power applications
bell-cot 5y ago
Any particular sources? From a quick web search, it sounds like hydrogen has a very different energy density (Joules/cu. m., or BTU/cu. ft., or whatever), very different combustion and leak safety characteristics, and can either leak through or embrittle many parts of the existing (natural gas) distribution infrastructure. If that's anything resembling correct...then the change-over would be more like replacing all-diesel fuel & engine infrastructure with gasoline.
pydry 5y ago
This is the oil/gas industry trying to keep themselves relevant. Thats why we keep hearing abouti it. Hydrogen can be cheap (extracted from natural gas) or green (electrolysis). It can't be both. Hydrogen is also a monumental PITA to store.
- bryanlarsen 5y ago
  Green hydrogen can be cheap if electricity is cheap. With the falling prices of renewables, that is quite likely to happen soon. But green hydrogen is only useful if electricity is cheap but batteries are expensive. The original article indicates why batteries aren't expensive and are likely to get dramatically cheaper over the next decade. That's why hydrogen is likely to stay irrelevant except for niche use cases.
  - tialaramex 5y ago
    Green Hydrogen is also good if you absolutely need Hydrogen. In this case, Green Hydrogen at twice the cost of getting it from Natural Gas is still a win. e.g. steel manufacturing can use Green Hydrogen for the Reduction reaction, as part of the alternate pathway without coal.
    - bryanlarsen 5y ago
      Oh certainly. I added the "niche use case" modifier. Compared to transportation and power generation, steel manufacturing is a "niche use case". It's a massive use case, but compared to the transportation and power generation use cases people usually hype hydrogen for...
  - jhgb 5y ago
    > But green hydrogen is only useful if electricity is cheap but batteries are expensive That is absolutely not true. How exactly will cheap batteries for example allow you to make ammonia for agriculture, the chemical industry, etc.? Current global ammonia production alone is worth something like two hundred gigawatts of power continuously pumped into electrolyzers. That's like ten percent of global electric generation at the moment.
  - _hypx 5y ago
    Compared to the cost of large-scale hydrogen storage batteries will always be expensive. This is why grids will use hydrogen for long-duration energy storage instead of batteries.
- jhgb 5y ago
  Electrolytic hydrogen can be cheap as long as 1) electricity for electrolysis is cheap and 2) electrolyzers are cheap. 1) is reasonably easily assured by shaving off overgeneration of electricity from renewable power plants. 2) is a matter of electrolyzer R&D, although it's true that it's slightly complicated by the former solution of 1) by decreasing their duty cycle. Nevertheless, 1) is the dominant problem. As for storage, it's true that storing hydrogen is problematic but once I calculated that even existing facilities for natural gas in, say, Germany would be sufficient for a whole month of the whole country's grid running off of hydrogen. This is less than the several months provided by using the same storage for natural gas, but since in the following decades, the demand for this gas is going to shrink severely as German buildings are going to be replaced by low-energy buildings (pursuant to the 2010/31/EU Energy Performance of Buildings Directive and the 2012/27/EU Energy Efficiency Directive, as well as presumably future regulations), this capacity might be freed up, and in any case it's a much larger capacity than is predicted to be required (https://www.sciencedirect.com/science/article/pii/S0014292118301107 https://www.sciencedirect.com/science/article/pii/S001429211...) for a 100% renewable grid in Germany. One interesting idea I don't know the feasibility of but is tempting anyway is ultra-large-scale liquid hydrogen storage. Considering the square-cube law and low density of liquid hydrogen stressing the structure (just 70 kg per cubic metre of liquid hydrogen tank, as opposed to 1000 kg per cubic metre of a water tank, for example), ultra-large-scale storage of hydrogen could be feasible in principle -- certainly much more than for example liquid hydrogen storage for a car, and in industrial settings to boot (as opposed to cars handled by ordinary citizens).
  - pydry 5y ago
    >even existing facilities for natural gas in, say, Germany would be sufficient for a whole month of the whole country's grid running off of hydrogen. As I understood it natgas storage facilities wouldnt keep hydrogen. It'd leak.
    - jhgb 5y ago
      Gas infrastructure used to deal with coal gas which contained ~50% of hydrogen. Somehow it worked back then. Doesn't seem like an unsolvable problem to me.
photochemsyn 5y ago
The only feasible way to do that is to use the hydrogen at the source of production to make methane, using direct air capture and reduction of CO2 (Sabatier process) as the carbon source. This is because existing methane pipelines would be embrittled by hydrogen and would soon fail, with disastrous consequences. Hydrogen from electrolysis is best viewed as an intermediate feedstock for further chemical synthesis, as with ammonia production, methane production, jet fuel production, etc. There is perhaps potential for dumping excess grid electricity into hydrogen storage tanks at power plants as a temporary storage system, i.e. converting the hydrogen back to electricity via fuels cells (not turbines!) to meet electrical demand later. Hydrogen storage requires special alloys to avoid steel embrittlement however, so it's fairly expensive.
- lrem 5y ago
  What is the efficiency of the hydrogen, air capture, methane, burn cycle?
  - mrep 5y ago
    34-44% for hydrogen and 30-38% for methane [0]. [0]: https://en.wikipedia.org/wiki/Power-to-gas#Efficiency https://en.wikipedia.org/wiki/Power-to-gas#Efficiency
    - lrem 5y ago
      Ah, great. So the incremental loss of going from crazy-talk to actually-reusable-infrastructure is not groundbreaking.

Which is effectively a battery! Hydrogen production is energy intensive, but if you produce it with excess energy capacity and then use it when it's needed, it's a decent energy storage method. Though mobile applications (air travel, trains, etc) are more likely to dominate in the shorter terms as it's lighter than batteries in high power applications

bell-cot 5y ago

Any particular sources? From a quick web search, it sounds like hydrogen has a very different energy density (Joules/cu. m., or BTU/cu. ft., or whatever), very different combustion and leak safety characteristics, and can either leak through or embrittle many parts of the existing (natural gas) distribution infrastructure. If that's anything resembling correct...then the change-over would be more like replacing all-diesel fuel & engine infrastructure with gasoline.

pydry 5y ago

This is the oil/gas industry trying to keep themselves relevant. Thats why we keep hearing abouti it. Hydrogen can be cheap (extracted from natural gas) or green (electrolysis). It can't be both. Hydrogen is also a monumental PITA to store.

bryanlarsen 5y ago
Green hydrogen can be cheap if electricity is cheap. With the falling prices of renewables, that is quite likely to happen soon. But green hydrogen is only useful if electricity is cheap but batteries are expensive. The original article indicates why batteries aren't expensive and are likely to get dramatically cheaper over the next decade. That's why hydrogen is likely to stay irrelevant except for niche use cases.
- tialaramex 5y ago
  Green Hydrogen is also good if you absolutely need Hydrogen. In this case, Green Hydrogen at twice the cost of getting it from Natural Gas is still a win. e.g. steel manufacturing can use Green Hydrogen for the Reduction reaction, as part of the alternate pathway without coal.
  - bryanlarsen 5y ago
    Oh certainly. I added the "niche use case" modifier. Compared to transportation and power generation, steel manufacturing is a "niche use case". It's a massive use case, but compared to the transportation and power generation use cases people usually hype hydrogen for...
- jhgb 5y ago
  > But green hydrogen is only useful if electricity is cheap but batteries are expensive That is absolutely not true. How exactly will cheap batteries for example allow you to make ammonia for agriculture, the chemical industry, etc.? Current global ammonia production alone is worth something like two hundred gigawatts of power continuously pumped into electrolyzers. That's like ten percent of global electric generation at the moment.
- _hypx 5y ago
  Compared to the cost of large-scale hydrogen storage batteries will always be expensive. This is why grids will use hydrogen for long-duration energy storage instead of batteries.
jhgb 5y ago
Electrolytic hydrogen can be cheap as long as 1) electricity for electrolysis is cheap and 2) electrolyzers are cheap. 1) is reasonably easily assured by shaving off overgeneration of electricity from renewable power plants. 2) is a matter of electrolyzer R&D, although it's true that it's slightly complicated by the former solution of 1) by decreasing their duty cycle. Nevertheless, 1) is the dominant problem. As for storage, it's true that storing hydrogen is problematic but once I calculated that even existing facilities for natural gas in, say, Germany would be sufficient for a whole month of the whole country's grid running off of hydrogen. This is less than the several months provided by using the same storage for natural gas, but since in the following decades, the demand for this gas is going to shrink severely as German buildings are going to be replaced by low-energy buildings (pursuant to the 2010/31/EU Energy Performance of Buildings Directive and the 2012/27/EU Energy Efficiency Directive, as well as presumably future regulations), this capacity might be freed up, and in any case it's a much larger capacity than is predicted to be required (https://www.sciencedirect.com/science/article/pii/S0014292118301107 https://www.sciencedirect.com/science/article/pii/S001429211...) for a 100% renewable grid in Germany. One interesting idea I don't know the feasibility of but is tempting anyway is ultra-large-scale liquid hydrogen storage. Considering the square-cube law and low density of liquid hydrogen stressing the structure (just 70 kg per cubic metre of liquid hydrogen tank, as opposed to 1000 kg per cubic metre of a water tank, for example), ultra-large-scale storage of hydrogen could be feasible in principle -- certainly much more than for example liquid hydrogen storage for a car, and in industrial settings to boot (as opposed to cars handled by ordinary citizens).
- pydry 5y ago
  >even existing facilities for natural gas in, say, Germany would be sufficient for a whole month of the whole country's grid running off of hydrogen. As I understood it natgas storage facilities wouldnt keep hydrogen. It'd leak.
  - jhgb 5y ago
    Gas infrastructure used to deal with coal gas which contained ~50% of hydrogen. Somehow it worked back then. Doesn't seem like an unsolvable problem to me.

photochemsyn 5y ago

The only feasible way to do that is to use the hydrogen at the source of production to make methane, using direct air capture and reduction of CO2 (Sabatier process) as the carbon source. This is because existing methane pipelines would be embrittled by hydrogen and would soon fail, with disastrous consequences. Hydrogen from electrolysis is best viewed as an intermediate feedstock for further chemical synthesis, as with ammonia production, methane production, jet fuel production, etc. There is perhaps potential for dumping excess grid electricity into hydrogen storage tanks at power plants as a temporary storage system, i.e. converting the hydrogen back to electricity via fuels cells (not turbines!) to meet electrical demand later. Hydrogen storage requires special alloys to avoid steel embrittlement however, so it's fairly expensive.

lrem 5y ago
What is the efficiency of the hydrogen, air capture, methane, burn cycle?
- mrep 5y ago
  34-44% for hydrogen and 30-38% for methane [0]. [0]: https://en.wikipedia.org/wiki/Power-to-gas#Efficiency https://en.wikipedia.org/wiki/Power-to-gas#Efficiency
  - lrem 5y ago
    Ah, great. So the incremental loss of going from crazy-talk to actually-reusable-infrastructure is not groundbreaking.