This is a simple fuel cell in its simplest form .
They are also not illegal to build , there clean and can be made to run off a cars electrical system. There Clean and environmentally safe, well this one is as it uses baking soda as an electrolyte. One can even use solar cells and wind mills to provide the power necessary to run the tiny reactors .
You can place "Traps" in key areas that can trap any access water to prevent it from entering in to the engine. There are even Fine mesh filters that can allow only gas to pass through and stop water dead in its tracks. Also back flash arrestors are sold. You will need this to prevent back firing in some cars.