Development of new supply takes time

The nice thing about these is that if you've got the storage part down pat, you can endlessly upgrade in place just by swapping out pumps and membranes.

If the argument is: they don't need to be commercially viable then you may be right. That's why China is running circles around us in battery technology. Because they invest in stuff to build up their technology base. Something we've forgotten how to do under the belief the invisible hand will magically solve our problems.