Recent Advances Fermentation Technology for Bioethanol Production as One of Potential Energy Sources

Rising the concern of energy security and the instability in fossil fuels price in addition to the adverse effect of these fossil fuels on the environment, made the world searching for alternative energy sources that are sustainable and clean to the environment. One of these alternative energies is bioethanol. Bioethanol is produced by microbial fermentation either from sugar crops or starchy grain crops depending on their availability as first-generation carbon sources for bioethanol production. These carbon sources are edible in nature and could lead into food-vs-fuel conflict and famine specially in developing countries. Inedible lignocellulosic biomass such as abundant agriculture byproducts and forestry waste are developed as second-generation carbon sources for bioethanol production. However so far, the excessive production cost of bioethanol from these lignocellulosic biomasses limiting the application of this technology for commercialization on large scale. In addition to the first and second generations of bioethanol technologies, there is third generation of carbon sources that currently under investigation for bioethanol production by gasification a wide verities of biomass sources into syngas (SG). Syngas is a mixture of carbo dioxide, carbon monoxide, and hydrogen. This syngas can be utilized as a carbon source for microbial fermentation using anaerobic bacteria such as Clostridium sp. to convert syngas into bioethanol and organic acids. In general, the interest in bioethanol as an alternative energy to fossil oil is due to its favorable properties as energy source.