AirTech wrote:Graydon wrote:
It's one of my favourite renewables proposals -- it's not like we don't know how to build sailing ships. It'd employ people. Direct-ammonia-fuel-cell powered electric cars have less power train mass than gasoline and ICE for pretty much any range, and as everything improved the price of energy would tend to come down. Plus we need the ammonia for fertilizer. It's nice clean catalytic tech.
Ammonia is seriously TOXIC. If you are synthesizing fuel go to methane - not toxic and packs more power in a unit weight or methanol of you want a liquid. Ammonium nitrate or sulphate makes a better fertilizer than straight ammonia. Other nitrogen compounds worth playing with are Hydrazine (which is safer in fuel cell service as it can be stored as a solid), Hydrazine Nitrate and Urea.
Surprisingly, methane is not better than ammonia in a fuel cell in terms of energy density; prying that carbon loose is expensive. (Prying that carbon off the other carbons to make the methane or off oxygens by splitting CO2 isn't easy, either. Ammonia synthesis is around 70% efficient.)
Ammonia isn't any worse than hydrocarbons; we've got lots of stats because it's made and used in immense quantities. The vapour rises, you know immediately if there's even a small leak, and ammonia vapour will not explode at STP.
Any of the useful hydrocarbons will go boom; any of the useful hydrocarbons will smother you. (and make you sick; "fuels puke" is a term for a reason.) It's a different set of hazards but it's not a larger set of hazards. (And even if you don't use it directly as a fertilizer it's a feedstock for making the other fertilizers.)
Also, hydrazine? Ki-yi-yi.
Any fuel cell fuel has the "how hard is it to pry the hydrogens off the other atoms?" problem; you're into a nasty tradeoff between storability and volatility. Ammonia really does look like a good choice.
