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First and foremost, hydrogen production needs to be moved to renewable power. At current production levels it generates almost a billion tones of CO2 annually a

by jiofih 5y ago

First and foremost, hydrogen production needs to be moved to renewable power. At current production levels it generates almost a billion tones of CO2 annually already. And then, total efficiency for hydrogen fuel is much lower than batteries. In vehicles for example, while 70-80% of grid energy reaches a cars’ wheels, the figure for LH2 is about 25%, a lot more of it goes to production and transport than its actual purpose. I think this clearly tells us that investing in new battery tech to increase density is a much more promising long term bet.

dublin 5y ago
Hydrogen is an energy STORAGE medium, NOT an energy SOURCE. The ONLY economically viable source of H2 today is cracking Natural Gas (and to your point, nearly always producing CO2 in the process). From both a lifecycle efficiency and pollution perspective (if you accept the ridiculous idea that CO2 is a pollutant), we're way better off just burning the NG, which is already the cleanest carbon-based fuel there is.
- ncmncm 5y ago
  NG is not a viable aircraft fuel. It is possible that cryogenic LCH4 could be, as SpaceX uses it, but its energy mass density is not enough to drive a wholesale conversion, as LH2's is. Batteries are also far from viable as energy storage for transport aircraft. Obviously, the LH2 fuel must be produced electrolytically, from electricity generated from renewable sources like solar, wind, or geothermal, not from NG as it all is today; I specifically called that out in the text that the above pretends to reply to, so it is hard to see why NG-generated H2 is mentioned here at all. LH2 generated on demand at airports does not incur transport losses. Identically, NH3 is today produced by consuming NG and exhausting CO2, which process also must be replaced with catalytic means powered from renewable sources, and H2 generated electrolytically. And, obviously there are conversion losses from solar/wind to electric to separated H2 and to chilled LH2, and then to accelerated air, just as there are losses extracting crude oil, transporting, refining, transporting again, burning, and exhausting it. End-to-end cost, including externalized environmental cost, is what matters. We need a carbon tax to help drive conversion. But the favorable energy mass density of LH2 overrides enormous conversion losses, which is the whole point.
- jiofih 5y ago
  Oil is also an energy storage medium, but I don’t think that distinction matters at all here.

by jiofih 5y ago

dublin 5y ago

Hydrogen is an energy STORAGE medium, NOT an energy SOURCE. The ONLY economically viable source of H2 today is cracking Natural Gas (and to your point, nearly always producing CO2 in the process). From both a lifecycle efficiency and pollution perspective (if you accept the ridiculous idea that CO2 is a pollutant), we're way better off just burning the NG, which is already the cleanest carbon-based fuel there is.

ncmncm 5y ago
NG is not a viable aircraft fuel. It is possible that cryogenic LCH4 could be, as SpaceX uses it, but its energy mass density is not enough to drive a wholesale conversion, as LH2's is. Batteries are also far from viable as energy storage for transport aircraft. Obviously, the LH2 fuel must be produced electrolytically, from electricity generated from renewable sources like solar, wind, or geothermal, not from NG as it all is today; I specifically called that out in the text that the above pretends to reply to, so it is hard to see why NG-generated H2 is mentioned here at all. LH2 generated on demand at airports does not incur transport losses. Identically, NH3 is today produced by consuming NG and exhausting CO2, which process also must be replaced with catalytic means powered from renewable sources, and H2 generated electrolytically. And, obviously there are conversion losses from solar/wind to electric to separated H2 and to chilled LH2, and then to accelerated air, just as there are losses extracting crude oil, transporting, refining, transporting again, burning, and exhausting it. End-to-end cost, including externalized environmental cost, is what matters. We need a carbon tax to help drive conversion. But the favorable energy mass density of LH2 overrides enormous conversion losses, which is the whole point.
jiofih 5y ago
Oil is also an energy storage medium, but I don’t think that distinction matters at all here.