Triple Pundit explains why being able to store renewable energy is crucial. It’s cost effective, as it can allow electricity to be released during peak hours when it’s needed and the price is higher. Also, it increases energy autonomy and also stabilizes the grid.
They have links to government sites explaining how such storage works.
Compressed air storage
Off-peak electricity is used to pump air into underground caverns, then released as needed to generate electricity.
Pumped hydroelectric
Pump the water uphill during off-peak hours, storing it in a reservoir, then release it to power hydraulic turbines.
Solar thermal energy storage
There are multiple methods for storing heat from teh sun to be used to power turbines.