Using methane for storage is very interesting, particularly since it can be chanelled through the gas system for cooking etc and can replace petrol and diesel for vehicles.
The Sabatier reaction is still EXTREMELY inefficient, especially if you tried to get electricity out. It does have its uses though. I would rather see "spilled" energy go to this than to be used in other ways. That is about as far as it goes.
It seems to me that marrying intermittent generation sources to such conversions would be a good use -
IF elimination of CO2 emissions is the aim. At present, there is effectively an upper limit on the amount of wind which is governed by the need to transport the lecky to the users AND to maintain grid stability under all conditions (especially under minimum load). I think there is an argument (which I know some people will automatically dismiss, but I'm going to throw it in the discussion) for adding large quantities of nukes a well as wind
and large quantities of electrical load making "fuels" (methane, methanol, whatever).
If you get to enough capacity to eliminate FF burning, then it's not really "waste" to use excess wind/PV/whatever to create other fuels that can displace FF elsewhere.
If the wind isn't blowing, you scale back fuel production to suit, if it is blowing, then you ramp it up. In the meantime, as long as you have enough fuel production facilities, you can keep the base load up and avoid having to "turn down" either source at night.
You could make the argument for doing that without nukes, if you can get enough renewables to have an excess most of the time. That's another debate that's been done to death before - where some thing it will be trivial to do, others believe it's not practical (at least for the UK as an island).
But once again, money would be a big factor - I doubt that any of this would come cheap.
The big thing that keeps getting forgotten when people squawk about "storage" (which IS mightily important) is to be influenced by the fact that for many decades we've had "on demand" energy on tap, and a lot of the basics are being forgotten ...
Yes you do keep saying it - when others are less repetitive supporting their opinions you call them trolls
To a certain extent change is possible. A small amount of change will be "fairly easy", but what are needed are really huge changes. These will not be easy, cheap, or quick.
While some things do lend themselves to load deferment - immersion heaters in DHW cylinders would be a good example. If you have a large enough cylinder, it could be heated at times of minimum demand which is what the old Economy 7 tariff was about. If you also have a roof, then it can also be heated by solar when it's available.
Some things don't lend themselves so easily. Most people have a fairly set daily routine - they get up in time to have breakfast before going to work, they get home form work, have tea, and then have the evening to do other things before going to bed. Like it or not, the business world still works round a fairly fixed core time - there is a certain amount of flexibility for many, but still core time for most. So meal times are somewhat constrained, and of course if you are going to have a cup of tea then that means boiling the kettle at the time.
So part of the day is set by outside influences. Human bodies really don't cope well without a routine - so you can rule out hoovering at 2am for the majority. You might be able to do some of the washing at 2am
if you are lucky enough to be able to sleep while the washer is running, and of course if you don't mind a pile of creased up washing to deal with in the morning. Mind you, for the washing you would do better to combine hot water storage (as above) with washers doing "hot fill", something that manufacturers have been busy programming out (or removing altogether) from new models, as the main load in a washing machine is the heater.
When talking about business processes, again there is some scope, but businesses are there to make a profit. They don't make a profit by having people and machinery stood around doing nothing while waiting for some wind. And few will tolerate a return to the days of queuing for work on a daily basis - "good news chaps, I can employ you today as the wind forecast is good". Some things can be done - there's talk of, for example, of turning down heating/air conditioning for peak lopping. But a lot that can't - easily and/or cheaply.
As you say, we've had decades of on-demand power. In fact we've had it longer than that. Arguably the rot set in with Arkwright and his mills - going back to 1771. That took cotton spinning from a cottage industry which would have been amenable to the sort of changes you wish for, to an industrial scale which isn't.
Change will take a long time to happen, and I genuinely do not believe it's possible to make the levels of change you talk about - not while maintaining anything resembling an industrial base to pay for it.
So given that the level of change needed to eliminate the problem, storage is going to be needed - or we carry on burning lots of gas for power generation.
In short - we need a mix because no single "thing" is going to fix everything on it's own.
