The world’s top battery manufacturer, CATL, expects sales of battery storage systems to account for half of its total sales in the coming years, signaling strong optimism about the battery storage sector as countries investing in alternative energy seek to make it more reliable. Storage is the only way to use electricity later than the moment it was generated, which is how electricity is normally used. With regions such as Europe and parts of Asia betting big on wind and solar electricity, battery storage has become a necessity.