2 ms·

Ammonia is a much better candidate, since it doesn't contain any carbon, so using it can't cause any CO2 emissions. But as others have said, the efficiencies ar

Ammonia is a much better candidate, since it doesn't contain any carbon, so using it can't cause any CO2 emissions. But as others have said, the efficiencies are horrible, so its better if we just figure out H2 transport and storage. Edit: for large ships, my personal bet is on liquid H2 storage and then combustion in gas turbines. You get a lot of synergies between cryogenic fuel and a gas turbine. Tupolev even built and flew a liquid H2 fueled narrow-body jet in the 80s.

maxerickson 9y ago
If you get the carbon from the air it doesn't cause any carbon emissions either. Or an existing stream that is currently being emitted into the air.
- semi-extrinsic 9y ago
  To your first point: correct. But the concentration in air is so bloody low for any chemical process (air is <0.5% CO2) that you'll have to put in huge amounts of energy. It's not going to be economically feasible. To your second point: capturing CO2 and then re-emitting it is completely off the table. It will be (or already is, depending on your interpretation of Directive 2008/98/EC) banned in Europe, likely with an exception for greenhouses (where they need to use CO2 for growing plants, and currently get it from burning natural gas).