Storage

Electricity storage can be achieved in several ways:

• Mechanical:  pumping and storage water or compressed air
• Electrochemical and electrostatic  batteries, capacitors and super conductors
• Thermal:  heat storage
• Chemical: hydrogen
  

At the present time global storage capacity is completely dominated by Pumped Hydro Storage at 99.3%. All types of battery are only 0.4%

Breakdown of capacity of storage capacity from IRENA 2017

In the future Hydrogen Gas could be used, but as yet this technology does not exist on industrial scale.

To compensate for the periods where the wind is off for a few days a large amount of storage would be necessary. A simple calculation can be made from the average wind production for 3 days which is about 500 GWh for the UK. This is greater than the global annual production of Li-ion Batteries, so such batteries or EV are impossible to use in the foreseeable future. s.