A Portable Battery That Runs on Saltwater – or Urine

South Korean developers have adapted 2,000-year-old battery technology for modern warfare.

The device, known as MetalCell, is a backup power source that runs on sodium and can keep a laptop charged for more than four hours, its maker says. The design is relatively simple: a small, ruggedized box with magnesium plates inside. If an electrical gadget — anything from a computer to a flashlight — runs out of energy, a soldier on the battlefield could pour saltwater into the MetalCell and use the device as an emergency power source.

via National Defense