there are effective ways of storing energy, but there isn't a silver bullet that has high efficiency, low cost, long storage duration and high storage capacity
Energy storage is a part of the problem. The good thing is, if we combine multiple energy production methods and connect it to a smarter grid with a smarter consumption profile, we can do with storing much less. The solutions are already known and are feasible.
The ultimate problem is, the transition takes a lot of time, certainly given it needs to be smooth, we don't want too many outages. And we seem be be running out of time.
Cost competition is biggest aspect in my mind. Is the storage competitive compared to alternative if power is free is good benchmark in my mind to start with.
And what are political and ecological implications of them. As I doubt even the Greens prepared to build up most effective pumped hydro locations anymore. Effectively flooding quite large areas. And also I take there is questions where to get the water from in parts of the world...