Hydrogen -> Ammonia -> Nitrogen component of Fertilizer is a huge portion of the modern food system.
If we need to mass produce green Hydrogen for Ammonia anyway, it'd be cheaper if we found other uses of Hydrogen while we were at it.
> to maybe make nitrogen
Ammonia Fertilizer is NH3. So that's 1x N2 + 3x H2 == 2x NH3, if I'm getting my chemistry correct.
But not "maybe", we are doing it, and we *MUST* do it. One of the biggest uses of fossil fuels in our life is our nitrogen fertilizer system. Decarbonizing our fertilizer is as big and important a goal as decarbonizing our transit.
And if H2 is useful for transit, then doubly so. We can use H2 for transit and then use H2 + N2 == Fertilizer and solve both at the same time.
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You can't use batteries to make Ammonia / Fertilizer. So we're going there anyway with regards to our "tech tree". Might as well experiment and see how feasible transit is.