Next Generation Hydrocarbon Biorefineries 3 rates, and the much smaller process footprints can also lead to lower biofuel costs than are possible using currently available biological pathways for producing cellulosic ethanol. To articulate the essential role of chemistry, chemical catalysis, thermal processing, and engineering in the conversion of lignocellulosic biomass into green gasoline, green diesel and green jet fuel, the National Science Foundation and the Department of Energy convened a workshop entitled "Breaking the Chemical and Engineering Barriers to Lignocellulosic Biofuels" on June 25-26, 2007 in Washington D.C., ancillary to the 2007 ACS Green Chemistry and Engineering Conference. Over 70 participants from 24 academic institutions, 20 petroleum, chemical and biofuel companies, and 7 national laboratories contributed expertise in chemical catalysis, chemistry, petroleum refining, nanotechnology, quantum chemistry, and engineering. This document is the result of that workshop. This roadmap to "Next Generation Hydrocarbon Biorefineries" outlines a number of novel process pathways for biofuels production based on sound scientific and engineering proofs of concept demonstrated in laboratories around the world. Roadmap highlights are as follows: Selective thermal processing of lignocellulosic biomass to produce liquid fuels (bio-oils) in distributed biorefineries (Chapter 1). Utilization of petroleum refining technology for conversion of biomass-derived oxygenates within existing petroleum refineries (Chapter 2).