SacredCowTipper -

Well, your cryptic remark indicates that the variability problem is recognized and that at least someone has been working on it.

Mind you, the problem of power variability does not just affect the actual N2 and H2 production units, but rather the entire operation, i.e., all the pumps, compressors, controls, safety features, etc., etc. As such, I would think that regardless of how you tweak the process to make it more flexible with respect to varying power, there still needs to be as least some on-site electricity storage, perhaps an amount sufficient to run the plant at normal capacity for several hours. It's either that or a back-up generator. Regardless of which is used, they both represent additional capital cost that must be factored into the overall economics.

One other perhaps minor technical issue comes to mind. While my knowledge of electrochemistry is quite rusty (not that it was all that great in the first place), is it not true that to operate an electrolysis cell efficiently, the solution has to have a fairly high conductivity which in turn requires a fairly high salt content? If so, would you not have to include salt as one of the process inputs? Not very expensive, but an additional cost nonetheless.