Introduction to Biofuels

The world obtains 86% of its energy from fossil fuels, 40% from petroleum, a majority of which goes to the transportation sector (www.IEA.gov). Well-recognized alternatives are fuels derived from renewable sources known as biofuels. There are a number of biofuels useful for transportation fuels, which include ethanol, biobutanol, mixed alcohols, biodiesel and hydrogen. These biofuels are produced from biologically derived feedstock, almost exclusively being plant materials, either food or feed sources or inedible plant material called lignocellulose or biomass. This chapter discusses technologies for production of liquid transportation biofuels from renewable feedstocks that can use existing infrastructure, so hydrogen will not be included. In addition, a specific emphasis will be placed upon the research opportunities and potential for application of system biology tools to dissect and understand the biological processes central to production of these biofuels from biomass and biological materials.
There are a number of technologies for production of each of these biofuels that range from fully mature processes such as grain-derived ethanol, the emerging technologies for cellulose-derived ethanol, biobutanol and thermochemical conversion technologies and immature processes such as production of hydrogen from renewable biological feedstocks. Conversion of biomass by various thermochemical and combustion technologies to produce thermochemical biodiesel or steam and electricity provide growing sources of bioenergy. However, like hydrogen, these technologies are outside of the scope of this chapter, as is the use of biological processing for upgrading and conversion of fossil fuels. Therefore, this chapter will focus on the current status of production of biofuels produced from biological-derived feedstocks using
biological processes.
Regardless of the status of development of the biological process for production of the biofuels, each process can benefit from research and resulting development activities using the latest biological research tools and techniques. Among the most recently evolving research tools is what is collectively known as ‘omics’ techniques, such as genomics, transcriptomics, proteomics, metabolomics and fluxomics, plus an ever growing omics word generation.1 These and other similar methodologies are central to understanding the interactive functioning of gene expression, resulting protein/enzyme production, which impacts the cellular metabolism and carbon and metabolite flow. These emerging system biology ‘omics’ tools are just beginning to be applied to understand and improve the biological processes involved in conversion of renewable plant and animal material to biofuels.