Subcritical water is considered as an environmentally attractive solvent for organic matters and it can be used to convert biomass to liquid form (biocrude), which is a mixture of oxygenated hydrocarbons with a wide molecular weight distribution. The biocrude produced at the biomass production site can be pumped through pipelines to a centralized bio-refining facility for the production of variety of chemicals and renewable fuel.

Studies have been conducted on the liquefaction of switchgrass in sub-critical water in a flow through reactor. Effect of heterogeneous catalyst K2CO3, and temperature on the liquefaction of switchgrass is studied. The finely grounded switchgrass (40-60 mesh size) is packed in a tubular reactor, and preheated compressed water / K2CO3-water solution is passed through the packed bed at constant pressure. Reactor temperature is increased using electrical furnace. Studies have been conducted for the temperature range 230-260 °C. Liquid product is analyzed for total organic carbon (TOC) content and yields phenols, monomers, degradation products of glucose and organic acids.