Seawater activated power source for long term missions

A seawater-activated power cell for low power, long life undersea missions is under development. The cathode uses dissolved oxygen in seawater as a reactant. The anode is a selected magnesium alloy which limits self discharge and extends cell life. The cell displays an open circuit voltage of about 1.6 volts. Under a load that would be equivalent to that required for a typical one year mission, eg., 2 to 3 watts, this power cell displays a working potential of 1.3 to 1.4 volts and has a total weight of about 32 kg. No pressure compensation is necessary since the structure is totally open to the seawater. Tests to date in selected ocean environments show that the cell operates well in low salinity water and in oxygen-depleted areas where other systems generally fail. Ocean tests have also shown that this power source can provide in excess of 700 Wh/kg for months. It has also been shown to operate both under ice and in fresh water