Chemistry - Are there other carbon free gasses that can be used for energy transport, apart from hydrogen?
Solution 1:
Yes, ammonia has been cited.
Per a source, 'Ammonia as a Hydrogen Source for Fuel Cells: A Review', to quote:
Like hydrogen, ammonia is carbon free and can be produced from any energy resource. However there are also some significant advantages in terms of storage and transport.
Solution 2:
Interesting question. These are my candidates, roughly in order from most practical to least practical. Some of these are poisonous, smell very bad, or are just plain undesirable. Environmental issues are not considered herein, but certainly would be in a real world potential application. For details on the chemical substances, see their wiki entries.
As per my first comment and one of the other answers, ammonia, $\ce{NH3}$, is a possibility. It burns in air, is easily liquified for transfort, and is produced in immense quanties already. It has many industrial uses and is not particularly exotic. But is is poisonous and must be handled with respect.
Nitrous oxide, $\ce{N2O}$, decomposes exothermically: this can be initiated with a catalyst and then thermal decomposition takes over. It can be used as a monopropellant and as an oxidizing agent. As 'laughing gas', it has substance abuse issues and does not support respiration. But it is produced in large quantities, is easily liquified for transport and it can be used as the oxidizer in the compustion of, e.g., ammonia.
Hydrazine, $\ce{N2H4}$, has used as a fuel in some rocket engine applications. Hydrazine derivatives such as unsymmetrical dimethyl hydrazine (UDMH) give better performance, but contain carbon. However, maybe amino-hydrazine or hydroxy-hydrazine, assuming they exist, would be viable possibilities. Hydrazine is very poisonous and nasty stuff to deal with. Derivatives probably likewise.
Hydrogen sulfide, $\ce{H2S}$, burns in air, producing water and sulfur dioxide, $\ce{SO2}$. The latter is produced in large quantities when sulfur is burned in the course of producing sulfuric acid, $\ce{H2SO4}$. So the $\ce{SO2}$ product of combustion of $\ce{H2S}$ would have potential commercial value. The downsides are that $\ce{H2S}$ is poisonous and is the main rotten egg smell in actual rotten eggs.
I will add to the list if I think of more.