**5.2 Physico-chemical means**

This involves the mechanical extraction of oil from lignocellulosic and algae biomass, where the oil produced is further esterified to produce biodiesel. Biodiesel is

**Figure 6.** *Biomass conversion techniques.*

usually blended with conventional diesel to be used as fuel for motor vehicles. The oil extracted from the biomass is highly viscous with polyunsaturated characteristics; therefore, transesterification processes which utilize either acids, bases, or enzymes as catalysts, convert the oil into fatty acid methyl esters (FAME) or fatty acid alkyl esters with glycerol as by-product. The esters produced from the transesterification process have lower viscosities and are comparable to conventional fuels [51].
