For at least 180 years, an electric bell at Oxford University has been ringing continuously — and no one knows exactly how it works. The university has covered the bell with a double-paned glass dome (who could study with such noise?), but the mystery of its battery has gone unsilenced. Built by a London instrument manufacturing firm in 1825 and acquired by Oxford in 1840, the item consists of two brass bells set below two batteries that look a bit like big wax candles. Between these bells is a small lead sphere, or clapper, that shutters back and forth, creating a near-constant ring. Estimates suggest the bell has likely rung more than 10 billion times.
This strange bell is powered by what’s called dry pile batteries, which use an incredibly small amount of electrostatic energy to move the clapper back and forth — so small that the two batteries have yet to run out of charge. Although no one’s sure exactly what’s inside the batteries (dissecting them would disrupt the bell’s historic run), the best guess is that they’re full of several thousand quarter-sized discs, made with metal foil and paper that has zinc sulfate and manganese dioxide added to it, all coated in sulfur. Oxford believes the bell has another five to 10 years of life left, as the ringing has slowed considerably in the past 40 years. (These days, it’s inaudible.) That hasn’t kept the Oxford Electric Bell — also known as the Clarendon Dry Pile — from being recognized as the “world’s most durable battery” by the Guinness Book of World Records. After 180 years in service, it’s an accolade that’s well-deserved.
A problem like climate change requires inventive solutions — including completely reimagining the battery. At its most basic, a battery is just a bundle of stored energy. As the world looks toward solar and wind for the renewable energy sources of the future, it helps to have a backup plan for providing power when the sun isn’t shining or the wind isn’t blowing. One of the most impressive energy-making schemes has already existed for nearly 40 years: England’s Dinorwig Power Station. Nestled inside Elidir Fawr, a mountain in north Wales, Dinorwig uses giant turbines to capture energy from water flowing from a lake at the top of the mountain to a lower lake, effectively creating a giant battery. When energy demand is at its lowest, the water is then funneled back up the mountain, ready to supply power at a moment’s notice.