Water cannot burn, even if it has good burning conditions. The only way it can burn is to apply other energy to split the water into its separate components of hydrogen and oxygen, which can be analyzed using chemical heat balance. Hydrogen and oxygen generate water and energy, which in turn must absorb energy provided by the outside world. In general, this energy comes from natural energy used and regenerated in a sustainable way. For example, solar energy, tidal power generation, biomass energy, wind power generation, geothermal energy, etc. A very efficient way to break down water or convert it into other fuels is a very potential and difficult topic. Furthermore, hydrogen storage is also a major problem. You can check online for more details.
Even in a perfect situatione (without any energy loss), due to energy conservation, you can only run this system indefinitely, and it is impossible to have excess energy. Also, there are a lot of losses involved, so this is not true.
You are equivalent to a perpetual motion machine, and it is more advanced than a perpetual motion machine. You also generate electricity, which is the same as creating energy.
The reason why perpetual motion machines have failed for countless years is that the designers have completely violated the law of conservation of energy. When a machine is running, its energy can only be converted from one form to another. If it operates outside, it must consume energy. If it doesn't consume energy, it can't do external work. Therefore, a perpetual motion machine can never be successfully created. It's donenc even less feasible for you. But if you can study it, it means you are very good.