The problem of fluctuating power from renewables will be solved. ....."
Do you have the same confidence that practical carbon capture and storage from coal or gas fired generators will be solved?
yes, the problem will be solved, and solutions are already starting to take shape! i myself have a 15KwH battery attached to the grid in the form of an EV vehicle, when im not driving it obviously, Nissan Leaf vehicles when plugged into the grid to charge, can be used as storage to smooth out those fluctuations in the UK. called Grid vehicles, the cars communicate with the energy providers, and when demanded, can return energy back to the grid from their drive batteries, or slow or stop their charging temporarily, or if needed can take up extra power when demand drops, by fast charging the vehicle.
How to Sell Power from Electric Cars Back to the Grid - Scientific American
Link to PDF paper from Uni of Denmark here
http://www.edison-net.dk/~/media/EDI...n%20study.ashx