The challenges of hydrogen for airliners, part 2: ecosystem
leehamnews.com
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1) If is is so workable, then why don't we have hydrogen test planes flying today? Are there any technological problems that remain to be solved?
2) How is hydrogen supposed to be better than synfuel kerosene produced with renewable energy? And note than any argument must include the cost of replacing every current airliner with an all new hydrogen one, as opposed to keeping the present airliners.
For a similar cost to an extensive LH2 infrastructure, various diesel-from-air solutions could produce simple non-cryogenic hydrocarbon fuels. (CO2 + H2 = CHC + O2)
Furthermore, recent advances in catalysts for hydrolysis, some directly from sun exposure with no detour through electric form, make production of hydrogen from water and light practical.
New airframes with lifting-body designs, already better than those used now, have more room for tankage as a side benefit.
The practicality of any idea can change very, very rapidly, as details of solutions to engineering problems change. Recently solar and wind power were impractical. Now they are cheapest, and coal-fired power is impractical.
One is like saying "it's cheaper if I dump my pollution in this river than using your new tech" and one is like saying "even after cleaning the output so thats its pure water and disposing of it properly to the same degree as your new tech, I'd still be making money doing the old tech plus cleanup".
H2 has so many storage and handling challenges that are going to be compounded when weight is an issue that its hard to see its future in the airline industry.
As explained in the article, gaseous hydrogen has been deemed infeasible for aviation and the idea is to use liquid hydrogen. No high pressure involved.
Cooling likely wouldn't be done, I assume any excess hydrogen boil-off that couldn't be burned immediately would be allowed to escape through an overpressure vent. (So ideally top it up right before taking off. There could still be a problem if the plane needs to queue a very long time for a congested runway.)
[1] https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft#Prop...
The other problem is that the reduction in wing area needed (due to lower weight) is offset by the increase in drag of the fuselage so the savings are modest if they even materialize.
Remember, aviation fuels need to work way above 10km above sea level.
Furthermore, replacing all the planes would take many decades, while synfuel kerosene might go into production much sooner.
Do the hydrogen airliner boosters take all that into account?
Sure, and other things too, like combustion benefits and hazards. But regarding your money worries - they don't need to happen overnight, just like electric cars don't replace gasoline ones suddenly.
Hydrogen fundamentally more potent fuel than kerosene - both by energy density and heat characteristics. Like with other commercial technologies, to be accepted it has to change traditions somewhat, which isn't easy. Safety is another important matter - it remains to be seen if hydrogen can be safely brought onboard to regular commercial liners, though advancements demonstrated by Toyota Mirai remind that progress doesn't stand still.
I wouldn't mind a future where we use syntin-based fuels or similar for aviation and push for max renewables and nuclear for power elsewhere.
Not really. Most of commerical aviation doesn't use leaded fuel anymore, and general aviation uses leaded gasoline because it is technologically still mostly stuck in the sixties.
Replacements for currently used anti-knocking agents are searched for, but less so specifically because most commercial use involves Jet-A1, and low-end general aviation uses MOGAS where possible due to general lower prices (though those tend to vary - sometimes AVGAS 100LL can be wildly cheaper than MOGAS)
Has the hydrogen storage associated with spaceflight been responsible for significant explosions. Flight vessels are made as thin walled as possible for a reason. Land bound containers don't have the same weight penalty.