Biological conversion technologies for the production of biofuels cover a range of fermentative and biological processes. These basic technologies have also been employed for decades in the production of ethanol (e. g. wine) from sugars via a two-step process of saccharification (hydrolysis of sugars)/fermentation using yeast (Scheme 1.2), followed by distillation of the alcohol produced to obtain a higher degree of alcohol purity.

Bioethanol is therefore the most common biofuel prepared by biological conversion.13 It is the most employed biofuel on a world level, with the USA currently being the world’s largest producer and Brazil the largest exporter, accounting together for 70% of the world’s production and 90% of ethanol used

as fuel.13

The common feedstocks employed for the production of bioethanol are energy food crops, including sugar cane, corn, wheat, maize and sugar beet, although research on lignocellulosics and woody biomass is under way and these feedstocks have a great potential for future biofuel production.

Through various steps, a wide variety of biofuels can be obtained, including bioethanol, biobutanol and other bioalcohols, biogas and biohydrogen. Biological conversion processes and technologies will be fully addressed in Part III of the book (Chapters 9-11), so we refer the readers to these chapters for further reading on biological conversion processes.