Innovative biological solutions to challenges in sustainable biofuels production

The rising prices, declining supplies, and concerns about environmental safety and energy security associated with the use of fossil fuels are driving the development and use of biofuels (Gonzalez-Garcia et al., 2010; Markevicius et al., 2010; Singh et al., 2010; Sahin, 2011). Biofuels in general can be defined as liquid, gas and solid fuels predominantly produced from biomass (Demirbas, 2008). In this chapter, we will specifically focus on liquid biofuels which have attracted world-wide attention due to their renewability, sustainability, common availability, reduction of greenhouse gas (GHG) emissions, and biodegradability (Demirbas, 2009; Gonzalez-Garcia et al., 2010; Balat, 2011). Currently there are two major types of liquid biofuels, bioalcohol and biodiesel, as alternatives to gasoline and diesel fuel, respectively. Among the various bioalcohols, bioethanol is currently the most widely used and biobutanol has great growth potential in the future due to its significant properties including high energy content, hydrophobicity, blending ability, compatibility with combustion engines, and octane rating (Kumar & Gayen, 2011). To date, liquid biofuels have been mainly produced in the U.S., Brazil and several European countries (Fig. 1A). Furthermore, there is a regional difference in the preference for biofuels types, with bioethanol preferentially produced in the American and Asian countries (e.g., U.S., Brazil, China, and Canada) while biodiesel is preferentially produced in European countries (e.g., Germany, France) (Fig. 1B). Bioethanol can be produced from three categories of raw materials: simple sugars, starch, and lignocelluloses (Balat, 2011). Biomass feedstock for biodiesel production is under active development worldwide, with rapeseed and sunflower oils predominating in Europe, palm oil in tropical countries, and soybean oil and animal fats in the United States; and development of additional feedstocks such as Jatropha oil and algae for biodiesel is also underway (Dyer et al., 2008; Knothe et al., 2009). In particular, microalgal oil is one of the major renewable biofuels with great potential for replacing petroleum-based liquid fuels (Cooper et al., 2010).