"The story begins back in the early part of the nineteenth century, when scientists had discovered that passing electricity through water splits it into its two chemical constituents – oxygen and hydrogen. The idea intrigued the young William – later to be “Sir” William – Grove and it set him pondering the possibility of doing the same thing, only the other way round. Was there a way to bring oxygen and hydrogen together to create water, but this time get electricity out of the process?" (Quoted from article)