The case for: (BTW, both sides of this "debate" accept future 'net zero' as a given)
- Theoretical: electrification of some current uses of fossil fuels is well-nigh impossible to envisage; but conversion to hydrogen-burning looks feasible
- Pragmatic / vested interests: this suits a lot of people very well - in particular the natural gas industries along the entire value chain, whose sunk costs are astronomical and whose risk of asset stranding looks quite real; and a load of engineers for whom the practicalities are well-understood, if a little challenging
- It's not difficult to see (or at least hypothesize) a future world where periodically there will be large amounts of 'spare' electricity generating capacity, e.g. when the wind is blowing strongly and demand is low: conversion into hydrogen for later use (maybe back into electricity again) might be a whole lot easier than building batteries that are big enough. Every green advocate whose pet project is inflexible, potentially surplus electricity (nuke, solar) or negative-flex (wind) resorts to "you can always make hydrogen with it" as a fall-back
The case against:
- The inefficiency of moving from electricity into hydrogen and back to electricity again is very great indeed (true)
- Dreams of there being lots of spare electricity of zero marginal value (or even sometimes negative) to make this economic are just that - dreams: electricity will almost always command a higher price than that, particularly when (ex hypothesi) vast swathes of heating and transportation load has been electrified
- Hydrogen is way too dangerous to be used in residential applications**
- Pragmatic / vested interests: labour unions dream of untold unionised jobs installing heat pumps and the vast home-adaption paraphernalia that accompanies them - really quite labour intensive, a decades-long programme, and not a service they can easily be substituted for by robots
- Ideological: we hate those old natural gas people, boo, hiss
You can see how, what starts life as something of an ideology-free economic debate descends into left-vs-right mudslinging, the Left tending to view hydrogen as a wicked capitalist ramp.
Me? As you've gathered, I'm always impressed when anyone forges ahead without waiting to garner subsidies: & that's exactly how the great hydrogen movement started. But that moment has passed: the professional subsidy-farmers have taken over, just as A&R men move in on creative new talent in the pop industry. And of course they are on both sides of the "debate", seeing as how there are subsidies available on both sides, too. So now it's really difficult to tell what's good solid analysis and what's BS & hype.
My guess is that:
- hydrogen for domestic use doesn't make much sense
- there will be specialised industrial applications where it does
- there will be odd, localised, maybe temporary situations where electricity really will be 'almost free' (e.g. in the middle of a remote hot place where there's no grid, plentiful solar and a big mining industry that currently uses a lot of diesel)
- it will be hard for hydrogen to compete as a means of strategic storage (via conversion) for electricity with other tools for balancing grids, even those with lots of wind capacity
** personally I wouldn't bet on that. Electricity can be quite dangerous, too, and engineers are quite good at solving easily-defined physical problems.