If you are interested in fuel cells, I would suggest materials science, as that field, and to a lesser extent chemical engineering, is where most of the research regarding fuel cells comes from. The materials engineers develop different microstructures for the anodes and cathodes needed to make more stable and efficient fuel cells.

Mythos was made by a couple of the old D2 devs and has very similar play style to Diablo. It's free right now, but I think only the European version is technically live. Things are in English, but some of the translations aren't so great, and there is only one half-decent website with info on finding items, though it happens to be in German. http://www.mythos-europe.com/