Energy is essential and vital for development and presently, the growth of global economy completely depends on energy. The use of fossil fuel as a source of energy is now widely accepted as unsustainable due to depleting resources and accumulation of greenhouse gases in the environment. Renewable and carbon neutral biofuels are necessary for environmental and economic sustainability. All over the world, governments have initiated the use of alternative sources of energy for ensuring energy security, generating employment, and mitigating CO2 emissions. Biofuels have emerged as an ideal choice to meet these requirements. Biofuel production using microbes is a totally renewable and environmental friendly way of alternative fuel production. Presently, bioethanol is produced at the industrial scale with the help of microbes and used as a transport fuel in many countries. Biomethane is also produced on large scale but it is not yet utilized for transportation. Hydrogen, biobutanol and biodiesel are in high priority agenda of several companies and may be used in near future as a supplement of gasoline, diesel, and kerosene. This paper reviews microbially synthesized biofuels which have potential to replace the present fossil fuels, either alone or by blending. The current article attempts to summarize the present scenario of global biofuel profile.
Keywords: Biofuel; Fermentation; Biomass; Energy; Substrate; fossil fuel