Energy density higher than liquefied Hydrogen

[octavian]

Hydrogen is the main fuel source for power generation with fuel cells, but its storage and transportation are still major issues. To overcome these problems, hydrogen has been stored and transported via other chemical compounds, such as alcohols, hydrocarbons, ammonia, etc. In many ways, ammonia is an excellent hydrogen carrier [1]; liquid ammonia represents a convenient way of storing supplies of hydrogen, boasting a specific energy density (kWh/l) 50% higher than liquefied hydrogen. Ammonia is also easily condensed at ambient temperature (under 8 bar of pressure), which makes it a good choice for transportation and storage. Even though ammonia is flammable within defined limits (16%-25% by volume in the air) and toxic (above 25 ppm) its presence can be detected by its characteristic odor (above 5 ppm). Ammonia is produced world-wide in large quantities (more than 100 million ton/year), which allows the effect of economy of scale on the cost of production. Its decomposition by electro-oxidation in alkaline media at low overpotentials is NOx and COx free with nitrogen and water as products of reaction [2].

The rest of this rather interesting article can be found here: Electrolysis of Ammonia: an in-Situ Hydrogen Production Process

Hope it was of interest.

[jibbguy]

The "five nine's rule" of H

That is interesting, but currently the main problem with electric fuel cells is that they require the "five nine's" of purity ; 99.999% Hydrogen or else the membranes will get contaminated rather quickly, and lose their power generating capability. So the problem would be precisely separating the H on demand to satisfy this very difficult requirement (...which is why stored H has always been used with them so far... requiring the huge infrastructure and dangers of very high pressure tanks). Perhaps in the future they won't be so prone to contamination.

But for burning H on demand (when purity isn't an issue), it sounds like an excellent storage medium

[octavian]

That is interesting, but currently the main problem with electric fuel cells is that they require the "five nine's" of purity ; 99.999% Hydrogen or else the membranes will get contaminated rather quickly, and lose their power generating capability. So the problem would be precisely separating the H on demand to satisfy this very difficult requirement (...which is why stored H has always been used with them so far... requiring the huge infrastructure and dangers of very high pressure tanks). Perhaps in the future they won't be so prone to contamination.

But for burning H on demand (when purity isn't an issue), it sounds like an excellent storage medium

and cheaper than petrol