4 ms·

I guess one could also just burn the hydrogen directly in a jet engine, which might be lighter than fuel cells and motors

by harg 4y ago

giantg2 4y ago
Why do you guess that? My assumption is that the deflagrenation rate is way too fast compared to jet fuel for that to work.
- namibj 4y ago
  Gas turbine power plants are built already that will just need the combustor switched out to be switched from current nat gas fuel to eventually pure H2 in some seasonal storage projects. Gas turbines themselves have no problem with hydrogen as a fuel, it's just the burners/fuel injectors/flame holders that need appropriate adjustments. Also, they can fly higher, because hydrogen is more flammable and will burn even in extremely lean mix that happens at very high altitude.
  - giantg2 4y ago
    I think the engine design has to be changed too. Basically a full engine swap. I initially saw their comment as meaning adapting the existing engines to use hydrogen. I see now that they might just mean using engines designed for hydrogen, not the jet engines we have today that use jet fuel. Yeah, the gas turbines would be easy to convert compared to jet engines.
    - namibj 4y ago
      Airliner jet engines are just gas turbines with a ducted fan in place of the generator, and all the heat exchangers/air filters stripped. Well, at least some power plant gas turbines share the power core with airplane turbofan engines. Technically they likely differ somewhat in the power turbine, as jet thrust from the exhaust is wasted on the ground and thus they try to extract more of the exhaust's power than for a plane, where it's a trade-off between turbine/fan weight and fuel efficiency from essentially gearing the exhaust velocity down to barely above flight speed (having double the exhaust velocity costs 4x the power but only gives 2x the thrust).
- jillesvangurp 4y ago
  There are rockets that run on hydrogen. There have been jet designs that run on it. There is even a company in the UK that is building combustion engines for heavy digging equipment that burn hydrogen instead of diesel. It's a great fuel. Fuel cells are potentially more efficient though.

I guess one could also just burn the hydrogen directly in a jet engine, which might be lighter than fuel cells and motors

by harg 4y ago

I guess one could also just burn the hydrogen directly in a jet engine, which might be lighter than fuel cells and motors

giantg2 4y ago

Why do you guess that? My assumption is that the deflagrenation rate is way too fast compared to jet fuel for that to work.

namibj 4y ago
Gas turbine power plants are built already that will just need the combustor switched out to be switched from current nat gas fuel to eventually pure H2 in some seasonal storage projects. Gas turbines themselves have no problem with hydrogen as a fuel, it's just the burners/fuel injectors/flame holders that need appropriate adjustments. Also, they can fly higher, because hydrogen is more flammable and will burn even in extremely lean mix that happens at very high altitude.
- giantg2 4y ago
  I think the engine design has to be changed too. Basically a full engine swap. I initially saw their comment as meaning adapting the existing engines to use hydrogen. I see now that they might just mean using engines designed for hydrogen, not the jet engines we have today that use jet fuel. Yeah, the gas turbines would be easy to convert compared to jet engines.
  - namibj 4y ago
    Airliner jet engines are just gas turbines with a ducted fan in place of the generator, and all the heat exchangers/air filters stripped. Well, at least some power plant gas turbines share the power core with airplane turbofan engines. Technically they likely differ somewhat in the power turbine, as jet thrust from the exhaust is wasted on the ground and thus they try to extract more of the exhaust's power than for a plane, where it's a trade-off between turbine/fan weight and fuel efficiency from essentially gearing the exhaust velocity down to barely above flight speed (having double the exhaust velocity costs 4x the power but only gives 2x the thrust).
jillesvangurp 4y ago
There are rockets that run on hydrogen. There have been jet designs that run on it. There is even a company in the UK that is building combustion engines for heavy digging equipment that burn hydrogen instead of diesel. It's a great fuel. Fuel cells are potentially more efficient though.