Unless there is a something I'm missing, it seems that large scale hydrogen production isn't very 'green'.
The problem is, all the people against serious climate action are also against ensuring all new hydrogen production be green hydrogen production. Their argument goes something along the lines of "the cheaper the hydrogen is, the more likely it is to be adopted, so we'll serve the climate better by funding grey/blue hydrogen until green hydrogen drops in price enough for mass adoption."
Which I might halfway believe if they weren't already doing everything they can to stall climate action. These are the people who turfed Turnbull for having too strict a climate policy.
Storage may still be a deal breaker for some applications, but if a handful of the many emerging electrolyser technologies commercialise you'll be looking at green hydrogen from the cheap 10am-2pm solar energy for <$1/kg pretty soon. 50c is an optimistic but somewhat realistic estimate by the 2030s
Being able to mix and match that with fossil fuels on existing infrastructure will cut emissions from those activities by >80% during the warmer months (or year round in the tropics)
Methane also has the advantage that it more or less will never compression ignite, so it can be mixed with the incoming air and then be ignited with a small amount of diesel (“pilot ignited”) or using a spark plug.
But since electrolysis is inefficient, it would require a lot of nuclear energy.
In return you get hydrogen and blue algaea are edible to boot!
Economies of scale are helpful; every house participating, with windows lined with the little things, would increase efficiency.
a nuclear plant scales better.
although the system you talk about might already exist and I'm curious to see a prototype.
Cody's Lab has a cheap algae production setup https://m.youtube.com/watch?v=64cEmjtwRgw
However we still don't feed everyone from small household gardens.
In any case, I'd be a pretty bad gardener. I'm more valuable to society (and thus my own wallet, too) when employed making computers run slightly better.
In general, subsistence farming has low productivity.
If I had to survive solely on crops I've grown myself I would perish. Putting aside economies of scale, I am lucky if I manage to grow a couple of decent size tomatoes or a decent carrot (singular). I'd be lucky to grow enough food for a day or week, let alone a season.
Partly this is because I live in an area with bad soil (too close to beach, sandy), and partly because I just seem to be a well meaning plant killer. Would be nice though. I have had some success with growing seedlings in a mini greenhouse, but as soon as they're out in the yard in bigger pots they start to fail.