By Deane Barker on October 12, 2007

The Mechanical Battery: This is a really great article on flywheels, which are the sleeping giant of energy storage. I’ve heard bits and pieces about them for years now, and it’s fascinating to think that a disc could spin at 100,000 rpm for years just waiting to be asked to discharge its energy.

A flywheel-based battery, on the other hand, can reach energy densities 3-4 times higher, at around 100-130 watt-hours per kilogram. Unlike the battery, the flywheel can also store and discharge all that energy rapidly without being damaged, meaning it can charge up to full capacity within minutes instead of hours and deliver up to one hundred times more power than a conventional battery. Ancient Egyptian potter’s whee. lWhat’s more, it’s unaffected by extreme temperatures, boasts an efficiency of 85-95%, and has a lifespan measured in decades rather than years.