Biomass is the renewable energy source of choice for the production of liquid transportation fuels. Significant quantities of ethanol are currently being produced from corn and sugar cane via fermentation. Utilizing lignocellulosic biomass as a feedstock is seen as the next step towards significantly expanding ethanol production capacity. However, in addition to substantial technical challenges that still have to be overcome before lignocellulose-to-ethanol becomes commercially viable, any ethanol produced by fermentation has the inherent drawback that it needs to be distilled from a mixture, which contains 82 to 94% water. Instead, direct thermochemical conversion of lignocellulosic biomass to a crude bio-oil has been proposed as an alternative, which does not require distillation, thus resulting in less energy input/unit energy output.

Polyhydroxyalkanoates (PHA) have received considerable interest as renewable resource based, biodegradable, and biocompatible plastics with a wide range of potential applications. More than 150 different hydroxyalkanoic acids have been identified as PHA constituents. These PHA monomers can be synthesized in a variety of configurations to produce a wide range of material properties. Physiological data and enzymatic studies have shown that there are two distinct classes of PHAs based on the number of carbons in the monomers. Scl-PHA (short chain length) polymers are comprised of monomers containing 3-5 carbon atoms, whereas mcl-PHA (medium chain length) polymers are comprised of monomers containing 6-14 carbon atoms.