Roger, there is no technology to store electrical energy that doesn't result in wasting at least 15% of it. For electric vehicles, the waste is justified - EVs are so efficient, in nearly every case emissions are lower than comparable vehicles with gasoline-powered IC engines.

Storing energy for re-use on the grid is a different story. Though renewables activists imagine grid-scale batteries charged exclusively by solar and wind farms, a battery installation owner would have to be crazy to limit charging times to only when the sun is shining or the wind is blowing. In practice, they are either charged by a grid mix, or directly from the output of a gas power plant. In the second case, losses increase emissions by 100%, effectively turning the gas plant into a coal plant.

With storage, the justification for attempting to power an electrical grid with solar panels and wind turbines goes from bad to worse.

I agree with Bob again. Hydrogen 

Shrinking demand for hydrogen in the fossil fuel refining and ammonia markets is a bad sign; those are basically the only markets in which hydrogen is worth more than fossil fuel (otherwise it wouldn't make sense to use fossil fuel to make the hydrogen).  For other markets such as heating and electric power generation, hydrogen is worth the same (per BTU) amount as fossil gas, so green hydrogen will have that much more difficulty competing. 

Of course transportation fuels like gasoline are worth much more than fossil gas, but the cost of storing and transporting hydrogen will act to reduce its competitiveness in that market. As Roger points out, perhaps hydrogen will be used to make storable transportation fuel; ammonia comes to mind as the only one that won't have an equivalent carbon tax (note that carbon taxes are unlikely to substantially exceed the cost of direct capture of CO2 from the air, so that won't avoid the cost penalty for storable hydrocarbon fuel).

As is often noted, the reason it is important that a large market for green hydrogen (or e-fuels) emerges is that the grid will be cleaner if clean energy production is over-built, and dispatchable fuel synthesis is used to balance supply and demand, rather than using under-built clean energy combined with dispatchable fossil fuel fired power plants.  Of course a nuclear-dominated grid needs less over-build compared to a low-capacity factor variable renewable dominated grid to achieve zero fossil fuel, so effectively the nuclear-rich grid is less dependent on finding viable markets for hydrogen and e-fuels.