A couple of thoughts. You can't form a reliable gird with PV and wind for reasons that are obvious. There are always fossil generators backing them up. That's a tidbit the greenies never like to mention.
Semi related is the stability of PV and wind. They produce ‘dirty’ power which has to be dealt with. Previously, grids didn't deal with it because it was such a small fraction and it could be accounted for.
Now the market/grids are correcting that issue (and others) with energy storage, ie batteries, and you need a lot of zeros to buy enough batteries to store even 1 MWH of energy.
I guess my point is that it's a complex topic. Pushing personal bias as the reason why things are the way they are, either for or against, is foolish.
The main point of the article, (explained within), is that despite the lower manufacturing costs of PV and wind, electricity prices are not going down but increasing.
The author cites California, Germany and Denmark as examples.
An electrical engineer back in the 80’s proposed a design for a magnetically levitated, electrically driven, kinetic energy storage system. He originally thought-up the design as a way to power launch devices to propel payloads into Earth orbit less expensively than rockets. Later, he realized such a storage system would initially be most likely used as a peak leveling system in an electrical grid. Scaled large enough, the device could store sufficient energy from intermittent sources to provide smooth delivery on a 24 hour basis.
The continuous iron ribbon driven element is actively levitated, with it’s path magnetically guided to form an elongated racetrack to loop back to a starting point. Linear induction motor/generators move power between electrical and kinetic forms at better than 98% efficiency. An actively controlled series of magnets holds the ribbon at a nominal operating distance from all components of the guide-way and magnetic diverter guide elements. The system is housed in a vacuum to mitigate energy losses from interaction of the kinetic component traveling at 11 km. second with atmosphere. Also the device would be placed in a tunnel sufficiently deep in the ground to contain all the energy released during a loss of ribbon type of accident.
The concept probably is valid, as a company in Finland is pursuing a storage design with many attributes of the original proposal. Their design unfortunately only alleviates some of the limitations of flywheels as energy storage devices.