Building gas power plants that run only a few weeks per year is very expensive. Just compare prices in Germany (gas) with China (coal) or Finland (nuclear).

A more economical way would be to build nuclear power plants that power electrolyzers most of the time and provide power to the grid when necessary.

In the US, gas power plants make more sense due to ridiculously cheap gas, but even then the capacity factor of those power plants is much higher than 10%.