Imagine if we could find a non-polluting, highly efficient source of power for our society's energy needs. One technology — the fuel cell — offers a strong and proven model. However, in order for the fuel cell to replace gas-powered engines and batteries, the fuel used to power it must be readily available. This video segment adapted from NOVA scienceNOW highlights the electrochemical reaction that takes place within a hydrogen fuel cell and explores the challenges of producing the pure hydrogen that fuels it.