There was an episode of Nova about energy storage that included a company that made kinetic energy storage devices. IIRC they had 5000 pound flywheels that spin

There was an episode of Nova about energy storage that included a company that made kinetic energy storage devices. IIRC they had 5000 pound flywheels that spin in a vacuum and can be installed in your home. Expensive to purchase and install but essentially unlimited lifespan and totally renewable.