Those gas plants may be cheaper build, but if the electrolyzed hydrogen is expensive the total operating cost is higher since the fuel is too expensive. If you're using single cycle gas plants you'll need even more of this hydrogen, and thus driving up costs. Are you really just comparing cost of construction and ignoring the cost of electrolyzed hydrogen fuel? And remember this is on top of the solar and wind that needs to power this electeolysis in the first place.
Also again, to convert hydrogen to methane you need a large source of carbon dioxide.
A summary of this comment is, "it's cheaper if we just ignore all the technical challenges of synthetic methane."
Nobody claimed electrolysis is cheaper than using natural gas. Nobody even claimed that electrolysis is cheaper than batteries at small scales. The claim is that electrolysis is proven technology that is a lot simpler to scale that lithium batteries.
> The claim is that electrolysis is proven technology that is a lot simpler to scale that lithium batteries.
And my point is that this is false. Electrolysis is not proven technology at scale, almost all hydrogen is produced through steam reformation. No, it does not scale better than lithium ion batteries. If we try to build it at scale it'll make solar and wind more expensive than nuclear power.
Would this cost money? Yes. But it would likely cost less than a grid based on nuclear power plants. The key insight is that hydrogen can feed combined cycle power plants, which cost a factor of 10 less than a nuclear power plant of the same power output. So, one could (if necessary) back up the entire grid with CC plants at a fraction of the cost of powering the same grid with nukes. If desired, one could use simple cycle power plants, which (while less efficient) are even cheaper by another factor of about 2, or 20x cheaper than the nukes.