BIOFUELS: Biodiesel giant enters petroleum business Amanda Peterka, E&E reporter Published: Friday, February 14, 2014 Renewable Energy Group Inc., the country's largest biodiesel company, is expanding into the petroleum business. Please subscribe to Greenwire to read the full story. Username: Password: Forgot your access codes? Recover them. Not a subscriber? Sign up for a trial. Ready to subscribe? Click here.