The companies say the main advantages of the cells are that they are very stable and can be stored for 20 years without losing effectiveness, their relatively high power output, and the benign casing left over when they are depleted, which can be thrown away with ordinary trash.

Disadvantages include the need for the separate casing to use them and the fact that they can't be recharged.

The cartridges contain small sheets of calcium hydride and water, which are mixed to produce hydrogen when they are snapped into the larger casing. As in other fuel cells, the hydrogen is then converted to electricity. Calcium hydride has more commonly been used to quickly inflate weather balloons and life vests.

As the cartridges contain a potentially dangerous substance, they won't be allowed on airplanes and are not well suited for extreme environments. The company has rated them as safe from between 5 and 40 degrees Celsius.

The companies are also planning to produce larger fuel cells using the technology, and are showing one about the size of a desktop computer at Ceatec.