I’m partial to sticking them to carbon atoms for storage (methane).
How would this compare?
How would this compare?
If you abandon the "smell nice" constraint, you can get an even higher hydrogen mass fraction. For example, n-pentane has a hydrogen mass fraction of about 16.8% and it's liquid at a pressure of 1 atmosphere and a temperature of 25 degrees Celsius, but it evaporates rapidly, so you need to keep it in a container.
If you don't mind pressurizing the container a bit, you could put ammonia in there, and it has a hydrogen mass fraction of about 17.6%.
To work with a circular system you would need carbon collection on all combustion engines. Try fitting one on a plane.
And now we’re down the path of fossil industry talking points where they will ”soon” implement carbon capture and storage.
Another option is ammonia. The maritime industry is particularly interested in that one due to hydrogen taking up too much space if you want to go across oceans.
Why would you need the carbon collection on planes? Surely a ground station would be equivalent and more sensible.
https://news.ycombinator.com/item?id=45313923
Direct air capture introduces processing massive volumes which causes extra energy usage.
The central point was that syngas, as it stands today, only really works if you have a concentrated carbon source due to the infeasibility of direct air carbon capture.
Meaning, for aviation to be freely able to release its previously captured carbon to the atmosphere we need a source for it. Capturing the exhaust fumes from a coal plant is just fossil emissions with extra steps.
One source could be biofuels and biogas from waste. But is that enough to run all airtravel on? Likely not. And if the carbon source is biofuels then we might as well just skip making syngas and run the airplanes on it directly.
The aviation industry have enormous problems to solve, and for it to work I think direct air capture needs to be solved. Or they need to manage with liquid hydrogen or ammonia. Come to think of it; ammonia and an airplane crash sounds like a terrible recipe...
For maritime shipping they alreay have engines running on hydrogen, methanol, syngas, syndiesel, ammonia and whatever else that is liquid at any temperature and makes a bang. They also have the space to install carbon capture systems if they choose to go down carbon based fuels allowing them to not be reliant on direct air capture.
This is why they truly like ammonia. It is a liquid with similar nastiness properties as methanol which they know how to deal with. Nitrogen is trivial to capture and it makes a bang when ran in an engine.
why not simply centralize the carbon collection and synthesis in some area (preferably where the sun shines a lot), then pipe/transport the resulting hydrocarbon fuel to where it is needed?
On the other hand, the output of a methane-powered fuel cell is 33% CO2 and 66% H2O - with the water being rather trivial to filter out. Even a dirty regular combustion engine outputs about 14% CO2.