Just to make sure that soldiers never run of power supplies when they need them most, a South Korean company has invented a pee- or saltwater-powered battery explicitly for military situations. The portable battery, dubbed as MetalCell, can power a laptop for four hours. The device contains certain magnesium plates that produce electricity when they react with sodium.
The box-shaped battery can power just anything from a laptop to a flashlight. The makers are already feeling around for its probable uses in non-military situations.