That's why researchers have been working hard to find the best type of battery for this type of large-scale storage. Lithium-ion batteries are great for gadgets and even cars, but on a larger scale they're too expensive and aren't very environmentally friendly.

Many researchers believe sodium-ion batteries are the answer. Sodium is cheap and environmentally benign and sodium-ion batteries would be well-suited for storing large amounts of renewable energy at once. The major obstacle to advancing these batteries has been a very short life due to the swelling of the anode with each charge and discharge of sodium ions, which when using a brittle base, causes the battery to fall apart after only about 20 charge cycles.