In this work, we determine the ultimate theoretical limit for the thermodynamic efficiency of the fundamental chemical processes that take place during the conversion of lignocellulosic biomass to liquid biofuels and consumer energy products.  In particular, we compare two idealised production pathways, one biochemical that uses enzymes and one thermochemical.  We find that the biochemical production pathway has approximately half the useful energy loss of the high-temperature thermochemical pathway, providing support for the pursuit of biochemical biofuel production technologies.

We also use a thermodynamic approach to investigate potential biofuel conversion technologies that go beyond the internal combustion engine paradigm, where chemical energy is converted into work via an intermediate heat transfer stage.  Our thermodynamic analysis highlights the inefficiency of the internal combustion engine technology and the need for alternative technological approaches.   We suggest two alternative future technology paradigms that promise significant improvements in the thermodynamic efficiency of converting biomass into useful energy products:  (i) fuel cells and (ii) coupled chemical reactions.  We discuss biotechnological approaches to each of these technology paradigms.