Every now and again, a rumor crops up that someone has invented a motor car that runs on water. Sadly, that still remains a rumor, but Green House Co Ltd of Japan will soon be marketing an LED lantern that runs on saltwater.

Given the catchy name of GH-LED10WBW, it’s presented as a saltwater lantern, but a magnesium/carbon lantern is more accurate and the design is simple compared to other saltwater batteries. The 680-gram (23.98-oz) lantern uses 16 grams (0.56 oz) of salt dissolved with 350 cc (11.83 oz) of water in a proprietary measuring bag and then poured into the lantern. The salt acts like an electrolyte in a simple wet battery, that uses a magnesium rod as an anode and a carbon rod as a cathode. The magnesium rod is replaceable because it is slowly destroyed by electrolysis as the magnesium ions travel to the carbon rod, generating electricity.

The 1.5 volts of DC power produced by the lantern is enough to run its ten-LED white light, which puts out 55 lumens of light. The lantern also includes a USB port to charge devices at 4.5 volts. The GH-LED10WBW runs for eight hours before the saltwater needs replacing, and the magnesium rod lasts 120 hours.

Marketed as an emergency lantern or for use aboard boats, it’s scheduled to go on sale in mid-September. No price has been announced.

View gallery - 3 images