Water is right there, but the hydrogen is really closely bound to the oxygen, and extremely hard to get out.
It's considerably easier to get H2 out of methane. Unfortunately, that process also yields CO2, so it's not helping the greenhouse gas situation.
Hydrogen proponents suggest a route where we start with "blue hydrogen" from natural gas. Then, when we've got a good H2 infrastructure going and a lot of excess electricity from solar, we can switch over to "green hydrogen" from water.
Skeptics point out that this is incredibly stupid, and that "hydrogen proponents" tend to be closely in bed with the fossil fuel industry. It looks an awful lot like an excuse to delay the elimination of fossil-fuel replacements like wind and solar.
There is this really dumb internet meme, that hydrogen is just there as a plot by the fossil fuel industry to keep selling fossil fuels.
What this ignores is that hydrogen must still be made even in a post-fossil fuel economy. It's not optional. Production of ammonia requires hydrogen, and without ammonia-derived nitrogen fertilizer billions of people will starve. About half the nitrogen atoms in your body came from synthetic ammonia.
The meme is really weird. In all other applications, we assume that fossil fuels will be displaced, by law and force if necessary. But somehow SMR will always be used to make hydrogen; the technology will somehow be immune to the forces that will be deployed against all other fossil fuel uses. It's really crazy when examined closely.
It's a meme because most of the people peddling hydrogen as a solution don't look at replacing existing uses of hydrogen (e.g. ammonia or as a process chemical) but instead try to sell it for dead on arrival ideas like fuel cell cars, blending in the natural gas pipelines, or burning it directly in homes for heat.
There's an order of magnitude more companies and hype around those use cases than there are around actually important ones.
Natural gas was also pitched exactly this way in 2008 or so. There's now a mountain of natural gas infrastructure being built, the the US is a major exporter, and for some reason people think the industry is going to just "switch off" that infrastructure when asked to.
This is 30+ year design lifetime infrastructure. Investments were made on that basis: no one is going to turn off anything.
Which is the best argument in favor of otherwise ludicrously inefficient power-to-gas storage schemes: if you could, by some miracle, undercut fracking extraction, then at the very least you'd only have to bankrupt the well-operators - not the pipeline, export terminals etc.
But I'm extremely skeptical this is possible and it will be fought against dirtily (see the anti-wind power campaigners).
Power-to-hydrogen is often attacked for being inefficient, but the alternative presented by the anti-hydrogen people for dealing with seasonal variations and long dark-calm periods is to just overbuild solar and wind massively -- in which case, most of the time power from these is just being curtailed. Apparently using this excess power with 0% efficiency is preferable to using it with nonzero efficiency making hydrogen.
The issue is that hydrogen makes no sense except for transportation fuel, where it also makes no sense. There are other options for stationary energy storage, and hydrogen is amongst the worst. i.e. if we can tolerate high losses, iron-air flow batteries are a much more reasonable option[1]
The thing is you pay for all of that pretty heavily - it's all more expensive with other drawbacks, but it's not nearly the complete pain that handling hydrogen is.
For long term energy storage, minimizing the capital cost of energy storage capacity is paramount. Round trip efficiency is not.
On that relevant metric, hydrogen is very hard to beat, particularly if proper geology is available (salt formations for solution mined storage cavities). Costs less than $1/kWh are possible.
Artificially heated geothermal may be competitive on that metric, but its RTE is likely to be even lower.
Yup, or things like sulphur thermal storage[1]. Also, hydrogen is pushed heavily by the fossil fuel industry, as it will provide another out for all their methane reserves (via steam reforming).
100% of anything doesn't really go away. We still use horse-drawn vehicles for some purposes. But we didn't have to get rid of 100% of the horse-drawn vehicles to get rid of the mountains of horse shit which used to accumulate on city streets.
Skeptics also point out that the blue part of blue hydrogen is carbon capture and storage, and nobody seems to be willing to pay for the extra cost of that.
yes :-) Think about it: why did Saturn V use hydrogen and oxygen? Because burning hydrogen produces more energy by weight than any other chemical reaction.
If putting hydrogen and oxygen together releases the most energy, then splitting water into hydrogen and oxygen would also take the most energy. Any other chemical reaction which yielded H2 would take less energy.
Are you serious? Water is right there!