A fuel cell is an electrochemical device, which combines hydrogen fuel with oxygen to produce electric power, heat and water. In many ways, the fuel cell resembles a battery. Rather than applying a periodic recharge, a continuous supply of oxygen and hydrogen is supplied from the outside. Oxygen is drawn from the air and hydrogen is carried as fuel in a pressurized container. As alternative fuel, methanol, propane, butane and natural gas can be used.

    The fuel cell is twice as efficient in energy conversion through a chemical process than through combustion. Hydrogen, the simplest element consisting of one proton and one electron, is plentiful and is exceptionally clean as a fuel. Hydrogen makes up 90 percent of the composition of the universe and is the third most abundant element on the earth's surface. Such a wealth of fuel would provide an almost unlimited pool of energy at relatively low cost.

    A fuel cell is electrolysis in reverse, using two electrodes separated by an electrolyte. Hydrogen is presented to the negative electrode (anode) and oxygen to the positive electrode (cathode). A catalyst at the anode separates the hydrogen into positively charged hydrogen ions and electrons. On the PEM system, the oxygen is ionized and migrates across the electrolyte to the anodic compartment where it combines with hydrogen. The byproduct is electricity, some heat and water. A single fuel cell produces 0.6 to 0.8V under load. Several cells are connected in series to obtain higher Voltages.

    The fuel cells are used for uninterruptible power supply (UPS), portable electric generators, portable computers and so on.

    In the future fuel cells can be commonly using source of energy for transport, for industry and for housekeeping.

    But for the time present high cost of fuel cells limits to its using with military and space.

    The main advantage of alkaline accumulators over the lead ones is the following:

• Possibility of operation in low temperatures conditions
• Possibility of short-time discharge duty with large current
• Short self-discharge
• Long shelf life