The plant is in Karlskoga - Ripley's Believe it or Not! featured this a couple weeks ago.
“The plant's supplier, Konvex, a company that produces biofuels from animals...is a subsidiary of Danish group Daka Biodiesel which says on its Web site that it produces and markets biodiesel and bio fuel oil using animal fat extracted from ‘by-products from slaughterhouses and primary agriculture.’”
Their website:
Not going to get a lot of fat from rabbits.