that some electro-magnetic force or gamma rays or something like that could cause the bonds between hydrogen and oxygen in a water molecule to release hydrogen and ignite.
But how much power is required to do that and how much power would be returned in a form that could be used to operate a steam or internal combusion engine? I expect the ratio of power in to power out is much higher than 1/1.
Perhaps this guy just stumbled onto some variation of electrolysis which has been known for many years.