Well, you're probably not going to get anything that divulges ready-to-go commercial technology, because that is what everybody is still working on intently, behind closed doors.
I'd recommend searching SAE.org for publications on the subject. But beware, most items will be quite esoteric and not constituted to give a beginner's introduction.
If you're looking for free material, try searching NREL.gov
These papers will be high level for the most part, I'm guessing, and deal with status updates and achievements rather than detailed methods.
"Schiefgehen will, was schiefgehen kann" - das Murphygesetz