Yes energy will be lost in the process but I believe that it will be able to store energy better then any battery we have avaliable and it will never need replacing.
thecoolbrian ,
Your idea itself is good and would work well in an ideal world, but there are some restrictions in the capabilities of the equipment and some less ideal processes involved:
• Dissociation of water into hydrogen and oxygen gives gases. In order to store these in acceptable volumes they will have to be pressurized.
• Having hydrogen and oxygen next to each other gives a nasty explosive mixture.
• Hydrogen, being the smallest atom, can easily escape and can penetrate many materials.
• Fuel cells normally do not like large pressures, which would be required to achieve less volumetric storage of the hydrogen and oxygen. Keep in mind that the water created by the fuel cell needs to be on the same pressure as the hydrogen and oxygen.
• Fuel cells presently do not have a high efficiency in energy conversion to electricity.
• In the shown configuration gravity is required to achieve a separation between the gases and water.
When you are able to overcome (some of) above restrictions, you have created a wonderful rechargeable battery.
