The real competitor for green aviation isn’t hydrogen, it’s bio-fuel. Bio-kerosene, bio-gas and bio-ethanol all have useful roles in aviation, and are essentially carbon neutral over their lifecycle. Zero carbon at the proverbial tailpipe is a lot less important when that tailpipe is at 30,000 feet.
Comment on New fuel cell could enable electric aviation
humanspiral@lemmy.ca 3 days ago
It’s a red flag that they don’t compare to H2, which has significant aviation FC prospects/research, and has even higher energy density by weight, and the advantage of exhausting water vapour and so fuel weight goes down during trip.
Sodium is also produced by electrolysis. It can make a lot of H2 and heat by reacting with water. In fact, the reaction of 1 ton makes 1.8mwh of heat, + 1.4mwh of H2 heat value (900kwh electric), where hot H2 might have extra energy potential for electricity or combustion (not sure).
Sodium metal costs $2000/ton. Reaction with water makes 42kg of H2, and so about $46/kg of H2 is too high. The heat would improve the efficiency of SOFCs (described matches article) by getting the heat for free, and maybe 1.2mwh/ton electric. SOFCs have always had the advantage of working with polluted fuel blends.
Perhaps if sodium or H2 production was combined with desalination process, then cost of green sodium or H2 could be lowered.
Patch@feddit.uk 2 days ago
humanspiral@lemmy.ca 2 days ago
bio fuels are not scalable. Much more solar energy (15x+ factor) is created by PV than by ethanol per area, and more efficiently turned into H2 (or e kerosene, btw) than the bio route. Bio route is airline PR to do something, but would make food scarce at scale.
CheeseNoodle@lemmy.world 3 days ago
iirc the issue with Hydrogen is that it has very high energy/mass but incredibly low density to the point that the fuel tank to contain a reasonable amount of hydrogen (say comparable to hydrocarbons) is even more prohibitive than battery weight.
humanspiral@lemmy.ca 3 days ago
300atm compressed H2 has more energy than batteries. 1500wh/L electric. 2.5kwh/L heat. LH2 is equivalent to 1100atm compressed. LH2 is right for aviation because the tanks are light/simple, and they are filled shortly before takeoff. It’s a big weight savings over kerosene.
surph_ninja@lemmy.world 3 days ago
Fuck the cost. The planet is going to be unfit for human habitation in a generation or two, while ecosystems and ocean current collapse kills everything else.
All that matters is if it’s cleaner. Stop ruling out options because they’re not market friendly.
humanspiral@lemmy.ca 3 days ago
Hydrogen is clean electrolysis too. Would cost less.
surph_ninja@lemmy.world 3 days ago
Yep. And I’m a big supporter. We should use the cleanest methods available as appropriate for each application.
AA5B@lemmy.world 3 days ago
The problem is that we don’t yet have a practical alternative to jet fuel, except high speed rail and Zoom. The technologies are all too young.
And it’s not just cost, it’s trying to make them useful enough. Batteries will not take you across a continent, for any cost.
We’re more at the stage of “fuck the cost. Give me another option to try”