Things have changed since 4 years ago.  Now in 2020 the utilities are installing the 'monolithic batteries' that Tom mentioned.  The grid scale battery at Hornsdale in Australia has about the same power as Tom's wind farm -- 150 megawatts.  Tesla installed it in a few months and it has paid for itself very quickly.  These are being installed in the US and other countries.  They are solving the problem of frequency regulation that Tom mentioned.  Thanks for the video, Tom.,(reply>), "paid for itself" 🤣🤣🤣