Hydrogen has been touted as a good approach to store appetite for make use of in portable applications similar to cars as well as generators for example. When it browns it only turns to water. Inevitably when you begin converting H2O to hydrogen in vast amounts a little will be leaked in to a atmosphere. What happens to that? Will it mix with oxygen molecules any way? Will it mix with sulphur molecules. we do not know, though we have seen immature ideas spin to a fiasco.