[jofer]

It requires more input energy, but it's been really good to see electrolysis of H2O for hydrogen generation take off. There are honestly industrial/grid scale operations actually starting now (as opposed to being constructed). E.g. Aces Delta in Utah. 220MW of wind/solar as input (i.e. equivalent to power for a medium sized city) As a disclaimer, my wife works on that project, but I think it's incredibly cool regardless.

Pyrolysis is a less energy intensive way to produce hydrogen, and does deserve more attention. But it still requires methane as a feedstock.

Hydrolysis let's use use hydrogen as essentially a fixed loss battery. It's perfectly complimentary to seasonally variable renewables like wind and solar. Batteries have too high of a loss though time for seasonal or multi-year storage. If you can store it (big if... Not everywhere has a salt dome like Delta, UT), hydrogen really is a great solution.

[georgecmu]

Pyrolysis is a less energy intensive way to produce hydrogen, and does deserve more attention. But it still requires methane as a feedstock.

So why is methane as feedstock a problem?

Isn't it better to spend less energy convert a ubiquitous, but environmentally harmful gas into hydrogen along with useful materials, than spend 4x more energy to convert a critical resource -- fresh water -- into hydrogen without any valuable by-products?

[_aavaa_]

Water is critical but not hard to get. The energy and cost required to take a m3 of dirty water and turn it into pure water is a rounding error compared to the energy required to hydrolyze it.

Yes methane is an environmental problem, even small methane leakages have a large GHG impacts. But the best way to deal with that environmental problem is to not pull it out of the ground in the first place

Plus for pyrolysis, you have to deal with the carbon which makes up 75% of the methane by weight. A non-trivial issue.

[MobiusHorizons]

I tend to be a fan of methane for its high hydrogen content per unit carbon as well as how much easier it is to store than hydrogen. However the argument against methane that I do find convincing is that the infrastructure for transporting and distributing methane leaks a lot. The argument is most compelling against residential distribution, where maintenance is harder to justify, but large leaks regularly occur, and that is very bad for greenhouse emissions.

I’ve always been curious about generating methane in industrial composting or from landfills and using it onsite for hydrogen generation. Not sure if the generating capacity is enough though, there is probably a reason it isn’t being done.

[kumarvvr]

Methane is not abundant, as such. There are specific sources of it, mainly through manual agricultural processes, or in natural systems. Natural gas is mostly methane, I guess.

[pfdietz]

> So why is methane as feedstock a problem?

There is inevitably leakage, and if even a small fraction does that it negates any global warming advantage on relevant timescales.

[Sevii]

An under considered side effect of adding renewables to the grid is that electricity prices occasionally approach zero during times of over production. No reason not to use that energy for electrolysis its going to be wasted otherwise.

[thomasmg]

The problem with electrolysis is the high capital cost. As long as / where the price of electricity near zero only some of the time, it is too expensive. (With batteries and more photovoltaics this might change a bit.)