Hydrogen is a promising fuel for many applications, and burning it doesn't destroy air quality. Unfortunately literally every material I've ever checked is pourous to it so storage is very hard, and because of it's pseduo metallic properties it can dissolve into steel and cause it to lose strength. A major problem for pipes/pressure vessels :(. It's possible we'll find some way to sequester it from steel and prevent that problem but idk how likely that is.

I think we'd probably have difficulty supplying modern cities with enough wood, plus environmental regs are tightening in many places and filtering air is expensive.

Methane is actually odourless! usually the gas is scented because people kept dying by leaving methane taps on. It is hard to burn fully to avoid build up of harmful chemicals in poorly ventilated environments.

I wonder about future fuels a fair bit. There are problems with basically everything, it's very frustrating. You can't even say fuck it and just make a plasma flame with arc discharge as you end up putting out UV and ozone and then you die. I guess fuck off powerful radiant heat lamps might work to substitute gas style stoves, although unfortunstely for me I don't see that becoming popular enough in my country to be anything except a rich person thing.