The world is currently facing an energy shortage crisis. The steady supply of energy from oil over the last century and a half has already passed its peak and is in exponential decline. The key to solving the crisis and ensuring a sustainable future lies in the development and use of renewable energy. Biofuel is a renewable energy source derived from organic matter and has great potential to replace fossil fuel as an alternative energy source. Humans used biofuels very early in the form of firewood for cooking and heating, but further research and development is needed to produce biofuels in forms more suited to current energy demand and dwindling oil and gas supplies. natural gas has accelerated the study of biofuel production. Much research is underway to find ways to produce biofuels cheaply and efficiently, making their use more feasible as a replacement for current non-renewable energy sources. Generally, biofuels are classified into three main categories: liquid fuel, biogas and solid biomass (refer to Figure 1 in Appendix 1). The first main type of biofuel is liquid fuel. This type of fuel is normally used in internal combustion engines to convert the chemical energy contained in the fuel into more useful mechanical energy. Liquid fuel biofuels are widely used by the transportation sector due to its high energy density and its adaptability for use in current transportation technologies without requiring costly modifications and supporting infrastructure (Jegannathan, Chan & Ravindra, 2011). Liquid fuel is further divided into biodiesel and bioethanol. Biodiesel is used in compression ignition...... middle of paper ......nsen (ed.), Renewable Energy (pp. 359-369). London, UK: Earthscan.John, G.I. (2001). Biomethane. Indiana, United States: Xlibris.Jong, W.D. (2009). Sustainable hydrogen production through thermochemical processing of biomass. In R.B. Gupta (Ed.) Hydrogen fuel: Production, transportation, and storage (pp. 185-226). Florida, USA: CRC Press. Nordic Council of Ministers. (2006). Biological waste treatment in Norway and Sweden: what works well and what can be improved? Copenhagen, Denmark: Nordic Council of Ministers.Oliveria, MDD (2008). Sugar cane and ethanol production and carbon dioxide balances. In D. Pimentel (Ed.), Biofuels, solar, and wind as renewable energy systems (pp. 215-230). New York, USA: Springer.Tester, J.W., Drake, E.M., Driscoll, M.J., Golay, M.W., & Peters, W.A. (2012). Sustainable energy: Choosing among the options (2nd ed.). Massachusetts, United States: MIT Press.