folks are used to battery tech being so important from cars due to energy density and weight being so important. But stationary energy storage can be simple. hydro-electric dams use water flowing downhill to generate electricity, and use excess electricity to pump water uphill. You can have a simple motor lifting a weight with a pulley as energy storage.
It's never needed new technology to solve, it's been intentionally held back so rich people can continue making money off all that oil extraction equipment and land leases they bought.