For about the next ten years it is definitely cost-effective to build out stationary storage using primarily lithium batteries; alongside increasing the penetration of renewables in the grid; and increasing the proportion of energy delivered as electricity vs as naked-fossils.
Poor round trip efficiencies of hydrogen are such that lithium battery storage is the more economic way to do this, certainly during the next decade. Where hydrogen has an additional value then it can be economically attractive - examples are shipping fuel (ammonia), or in green steel/etc production, or in liquid aerospace fuels. So to an extent doing these projects is also worth it on an R&D and scaling-up basis, but is more commonly just cynical greenwashing of fossil stocks and failing CCS schemes. It is important to carefully sift between these.
My personal opinion is that once we've gone through that (this !) decade we will discover that the economic/technical path dependency wil so greatly favour batteries that the following decade will naturally follow with very few and rare genuinely viable hydrogen cases.
Turning to grid, please understand HVDC is not a silver bullet, people here should have better understanding than journalists. Yes, HVDC is important, but in reality there is a continuum of voltages and currents from lower HV AC to higher HV AC, and only at the very highest of both voltage and current does it make sense to go to HVDC. Almost all use cases do not require, and should not receive, HVDC, as normal HVAC is plenty good enough. Note by the way that USA has a pretty weak (antiquated) grid in many areas which could do with some good old fashioned modernisation via HVAC projects long before thinking about HVDC. But the grid build-out is a balancing act of many factors. Two of the more obvious ones are economics of grid vs economics of storage. Others are who controls the grid vs who controls the storage, and who controls the grid making factories, and who controls the battery making factories, and how quickly can either/both scale up. In batteries everyone is running around doing mine-to-cell studies. In grid not so much, as there are some manufacturing choke points that are controlled by some key players, who are sometimes only only , maybe two, sometimes three boards of directors (or network/chains thereof) making quite serious long term manufacturing capacity decisions for the world. That is quite a different gaming space than the wild west of 20-50 players scrambling in the mosh pit for mine-to-cell capacity, and a very different dynamic results.
