[alancalverd]

Or methane - less corrosive than ammonia and the source of much industrial hydrogen nowadays.

Hydrogen storage in palladium is a popular process if container weight isn't a problem.

But if you really need 40 tonnes of payload in one shipment, liquefaction is probably the only practicable method, and you'll need a barge to carry 600,000 liters. The good news is that the fractional losses from a tank of that size will be very small. 

[Bored chemist]

For the benefit of those who don't understand the problem...
Burning methane creates CO2.
 Carbon neutral methane is possible but not common.

[Petrochemicals]

How about pipes, and huge gas storage containers dotted here and there
.

[Bored chemist]

The reason to use water is to make hydrogen less dangerous during transportation.

How would water make hydrogen less dangerous?

[alancalverd]

You could use it to put the fire out, if hydrogen were a dense solid.

[alancalverd]

For the benefit of those who don't understand the problem...
Burning methane creates CO2.

Who's talking about burning anything? This guy just wants to transport 40 tonnes of hydrogen in one manageable shipment. He could do so by shifting 320 tonnes of liquid methane (or 350 tonnes of ammonia, as you suggested) and extracting the hydrogen at the destination, but however he does it, he will need a barge, not a truck.

[Bored chemist]

Who's talking about burning anything?

You.

People get overexcited about hydrogen fires,

among others.

[alancalverd]

.

Who's talking about burning anything?

For the benefit of those who don't understand the problem...
Burning methane creates CO2.

Ipsi dixit

[Bored chemist]

Ipsi dixit

I guess you mean
https://en.wikipedia.org/wiki/Ipse_dixit
"Ipse dixit (Latin for "he said it himself") is an assertion without proof, or a dogmatic expression of opinion"
Are you saying that burning methane might not produce CO2?

Feel free to repeat this school experiment, using methane instead of wax.