A hybrid hydrogen-carbon (H2CAR) process for the production of liquid hydrocarbon fuels is proposed wherein biomass is the carbon source and hydrogen is supplied from carbon-free energy. To implement this concept, a process has been designed to co-feed a biomass gasifier with H 2 and CO2 recycled from the H2-CO to liquid conversion reactor. Modeling of this biomass to liquids process has identified several major advantages of the H 2CAR process. (i) The land area needed to grow the biomass is <40% of that needed by other routes that solely use biomass to support the entire transportation sector. (ii) Whereas the literature estimates known processes to be able to produce Ϸ30% of the United States transportation fuel from the annual biomass of 1.366 billion tons, the H 2CAR process shows the potential to supply the entire United States transportation sector from that quantity of biomass. (iii) The synthesized liquid provides H 2 storage in an open loop system. (iv) Reduction to practice of the H 2CAR route has the potential to provide the transportation sector for the foreseeable future, using the existing infrastructure. The rationale of using H 2 in the H2CAR process is explained by the significantly higher annualized average solar energy conversion efficiency for hydrogen generation versus that for biomass growth. For coal to liquids, the advantage of H 2CAR is that there is no additional CO2 release to the atmosphere due to the replacement of petroleum with coal, thus eliminating the need to sequester CO 2. biofuels ͉ coal ͉ hydrogen ͉ oil