There's a fair amount of biogas already in the network, I am on a Green Gas tariff from Ecotricity. Not sure you could put hydrogen though the existing pipes though.
There is testing underway now, with the aim of converting the UK gas networks to 100% hydrogen....
https://www.h21.greenThis will be an evolutionary process: hydrogen can be blended with natural gas up to, I understand, 20% without changing burners, jets, etc. An immediate 20% reduction in CO2.
Trials are underway.
https://www.northerngasnetworks.co....-uks-first-trials-on-public-gas-network/Converting to 100% requires changes to burners and jets, but those of us old enough probably remember conversion from town gas to "HighSpeed" natural gas.
Central heating boilers vent their exhaust outside, there will be more steam, but that is OK.
Gas cooking is another matter: again, those of us old enough will remember the level of condensation produced by town gas, pure H2 will produce a lot more. Condensation will be an issue for many. So probably better to force the conversion of gas cookers to electric.
Hydrogen has almost twice the calorific value, as kw/kg, than natural gas. This will allow boilers to be more efficient.
