Difficult? Yes. But it’s a solved engineering problem. There are chemical industries that need hydrogen. It is being transported and stored for decades. There are even small pipelines in operation for a long time by now.

Of cause it has started. Germany has plans of what is to be its hydrogen backbone. Electricity is set to be about 80 % renewables in 2030. So slowly starting to build up the hydrogen infrastructure starts now.

For long term storage most countries will need more than pumping hydro. But green hydrogen can be produced from wind and solar to use in times of need in claasic power plants adapted for hydrogen. This technology also exists. But it is very inefficient, so should and will he used only as a backup.