It will be interesting to see how sodium ion batteries will compete since their alkali metal is far more abundant than lithium, especially in stationary applications that don't need high energy/mass or energy/volume.
Perhaps surprisingly, round-trip efficiency matters a lot less than other things, for storage not drawn down often. And, it matters a lot less everywhere than only a short time ago, because top-line generating capacity has got so cheap, you can just build out enough more of that to make up the difference. If your liquified hydrogen is slowly boiling away, you just top up your tanks now and again.
The important difference from batteries I call attention to is that in batteries, you can only store exactly as much energy as you buy expensive batteries to keep it in. But for synthetic chemicals (and liquified nitrogen), the only expensive parts are what you use to synthesize them in, and maybe the way you get the energy back. Those capacities are measured in watts. Saying tankage is cheap is to note that there is no upper limit on the amount of tankage you can have, and the watt-hours you can bank; your bottleneck is only the conversion rate.
This is all aside from the fact that tankage can be shipped, both out, generating revenue from excess generating capacity, and in, if local storage gets drawn down too far.
So, batteries will be used for short-term storage. Iron-air battery factories are under construction, and those will be much cheaper than lithium, and will be used, but however much cheaper they are than other batteries, they cannot match empty tankage.
I think there are a lot of use cases for those fuels that don't even require a lot of long term storage, my current favorite being hydrogen fuel cell powered semi trucks that already burn a lot of diesel crossing places that have a lot of renewable electricity potential but not enough transmission (i.e. wind in the Great Plains and sun in the desert Southwest). This would get around the issues with batteries eating into truck weight limits.
Also, the idea of freight trucks "sailing" across the country on wind power is just an appealing narrative.
They might sell the excess to nearby truck stops. Ammonia is not quite as dense as diesel, but trucks typically have enough room for it. Advantage is trucks (like farm tractors) can be cheaply retrofitted to burn ammonia.
I see reports about a problem of UK farmers who make more from dedicated solar, per hectare, than they were making growing. The problem may be self-limiting: they may end up unable to compete with farmers doing double- or triple-use, with solar, wind, and cultivation in the same field. Then, farmers not doing it will end up needing to, as prices decline.
