I think @koanhead us right, It certainly sounds like they are talking about splitting water into H2 and O2 then powering a fule cell with them. The problem is that is takes energy to split the two constitutionals of water apart—lots of energy. If the conversion process in both directions; water + energy = gasses, gasses = energy + water; were 100% efficient, you’d still not gain any energy. It would take as much energy as it yielded to run the process. But no process is ever anywhere near 100% efficient. You’d need to put lots of extra energy into the system from somewhere in order to split the hydrogen and oxygen in water apart. They have a great affinity for one another and don’t split up on a whim.
They claim to have a membrane that splits the water into its component gasses through a chemical reaction. If that’s so, then the question is how long till the membrane is consumed and must be replaced. The link @jerv provided mentions that the membrane “engine” costs some $2 million yen, or about $18,700. And that’s before you wrap a car around it. So if you have to replace the membrane often, this may be more illusion than real solution to renewable energy.