A flywheel is a mechanical device that stores rotational energy. It consists of a heavy wheel that spins around an axis, and its inertia helps maintain a consistent speed. When energy is added, the flywheel accelerates, and when energy is needed, it can release that stored energy to help power machines or systems. Flywheels are often used in applications like electric vehicles and energy storage systems. Flywheels can improve efficiency by smoothing out energy fluctuations. They can quickly absorb energy during low-demand periods and release it during high-demand periods. This capability makes them valuable in renewable energy systems, where they help balance the intermittent nature of sources like solar and wind energy.