Is the hydrogen used as fuel in internal combustion engines gas, compressed gas or liquid ?

Question

and am I correct in assuming it must be delivered by injection?

Answer 1

BMW uses liquid, but keeping it cool is a limitation, the warmer it gets the faster it evaporates.

Answer 2

At the point of delivery it's a relatively low pressure gas.  In storage I think high pressure is the least tear weight and easiest to accomplish and what I use on my small engine conversions.   Injection is preferred but not necessary.   Just dump it in behind the intake port.

Answer 3

Its going to be a compressed gas, hydrogen has to be supercooled to be in the liquid state.

Answer 4

Fantastic question.

How to store hydrogen in a car is still being worked on.  Gas, liquid, or even solid forms are all being tried,  (not solid hydrogen, hydrogen incorporated into a solid)  No clear winner yet.  Most people are currently using compressed gas for prototypes - simplest.