The radio waves require an electrical current, which requires a generator, which requires a fossil fuel (or nuke).
Can’t get something for nothing. The energy released by the burning hydrogen must be less than the energy stored in the burned fossil fuel that runs the electric plant that runs the radio generator.
Sorry, that’s the physics of it.
I still think the picture of water on fire is really cool. Surely that more than makes up for a few kilowatts.