He'll be studying third generation biofuels... that's algae to you and me:
"Extracting oil from algae to produce a more sustainable biofuel is one of the most promising and exciting areas of biofuels research today," said Sayre, formerly a professor in the Department of Plant Cellular and Molecular Biology at The Ohio State University. "Algae have significant potential as a clean, renewable, and economical fuel source. And, because algae are not used as food, they are a biofuel source that does not compete with the food supply."
I've asked Enterprise if it has any details of the average fuel efficiency of its fleet of cars over the past five years and how it has changed over that time. Rental companies with large fleets could have some power in getting car makers to produce vehicles which are more efficient... I'll be asking other rental firms.