How efficient are the ways to store hydrogen?

Question

I know these some ways to store hydrogen:

hydrogen under pressure, liquid hydrogen, ammonia...

How efficient they are?

Thanks

Answer 1

Good question.

-Hydrogen under pressure   ----> more than 90%

energetic density=900 kwh/m3 at 300 bar

-Liquid hydrogen  ----> about 40%

energetic density= about 2500 kwh/m3

energetic value=about  140000 kj/kg

-Ammonia  ----> about 85%

http://www.psaplants.com/fertilizer-indu...

(It can be important to read the "psa nitrogen gas plant" section, it's the way how nitrogen is easily separated from air at room temperature)

Energetic density=about 3500 kwh/m3

Energetic value=about 21000 kj/kg