[mikec3010]

Could you store renewable energy via electrolysis, and instead of having storage tanks of dangerous hydrogen at home, pump the gas back into a grid? Most houses have natural gas lines and those are relatively safe. Would it be viable to have "hydrogen lines" that just ran in reverse when excess renewable energy is produced? Then draw off it to a home fuel cell during peak demand?

[pjc50]

Why on earth would you do this at home rather than at a central facility where it's cheaper and easier to handle bulk gases?

You can incorporate hydrogen into the grid but only up to a point: https://www.telegraph.co.uk/business/2018/01/06/hydrogen/ and it has issues https://www.nrel.gov/docs/fy13osti/51995.pdf

[mikec3010]

You would do this at home because that is where residential PV is located. Of course it's more obvious to send the power back down the wire and, as you said, convert to hydrogen centrally.

My question looks silly now in contrast, but it was thought up considering that grid buyback isn't going so well in the us, and focusing on a safe way to store and use hydrogen as a battery competing with flywheels or lithium battery cells, or centralized pumped hydro, etc. Just a hypothetical.