Fuels Cells 101 is a great resource from UTC Power (United Technologies Corp) that explains how a fuel cell works. There is also a section on energy basics.
While this is a commercial of sorts for UTC Power's fuel cells, the site explains how fuel cells work and why they are important to us very well. There are diagrams with explanations, photos, and videos.
Fuel Cells are an important energy source for our future and we should be educating our students about them.
Other Resources on Fuel Cells: