Bioenergyindicates to sustainable power source generated from biomass. Biomass is anynatural organic material which has the capability to stored sunlight in theform of chemical energy. Increase in energy consumption and depletion of fossilfuel reserves has necessitated the demand for alternative energy fuel sources.Biofuels are another option to petroleum products, which can be utilized aloneor in blend with other petroleum products, for example, petrol.
Biofuels aregrouped into in the first, second, third and fourth generation biofuels (Joshiet al. 2012). Firstgeneration biofuels, which have been chiefly extracted from food and oil cropsincluding rapeseed oil, sugarcane, sugar beet, and maize (FAO, 2008) as well as vegetable oils and animal fats usingconventional technology (FAO, 2007). It is anticipated that the development ingeneration and utilization of biofuels will proceed, but their effects towardsmeeting the energy demands will remain limited due to competition with food andfiber production by using the agricultural land, absence of well managedagricultural practices and high water and manure requirement. Usually, firstgeneration biofuels has great impact on global food market and food securitywhich generated a lot of controversy. This question marks their potential toreplace fossil fuels and sustainability of their production (Moore 2008). The startof second generation biofuels is projected to produce fuels from theagricultural residues, forest harvesting residues or wood processing waste (Joshi,,2012), rather than from food crops.
However, the conversion technologies arenot so successful and have not reached the scales for commercial exploitationwhich has so far inhibited any significant exploitation.Conditionsfor a technically and economically viable biofuel energy resource are that(Khosla 2009): it should be competitive in price than petroleum fuels; it shouldrequire non-agricultural land for production; it should help in CO2sequestration and it should use low water. Biofuels from microalgae may wellmeet these conditions and for that reason make a valuable contribution toachieving the primary energy demand, and at the same time giving environmentalbenefits (Wang et al. 2008).Microalgaeproductivity is high and have faster growth rate as compared to terrestrialenergy crops and can be easily cultivated on non-agricultural land withoutgiving any competition to food crops and security. As we know, microalgae arephotosynthetic organisms using CO2 for their production, it alsohelps in decreasing the greenhouse gases.
There are so many species ofmicroalgae which can grow on fresh, brackish, sea and even in the sewage water.Microalgae can accumulate approximately up to 60% oil per dry weight of biomassunder such conditions (Chisti, 2007). The algal oil extracted from biomass candirectly be converted into biodiesel which is an environment friendly and alsorenewable biofuel (Pandey et al. 2016). In this way, microalgae have gainedattention as a possible producer of biodiesel and offer strong contention as afavorable feedstock for the production of biodiesel along with other lipidbased biofuels and numerous other byproducts (Wijffels and Barbosa, 2010;Scott, et al. 2010).
Microalgae also have the ability to producedifferent types of renewable fuels that is capable of meeting our future needsfor transportation fuels. These include biodiesel derived from microalgal oil(Banerjee et al. 2002; Gavrilescu and Chisti, 2005); methane produced byanaerobic digestion of the algal biomass (Spolaore et al. 2006); andphotobiologically produced biohydrogen (Fedorov et al. 2005; Kapdan and Kargi,2006).
This chapter emphasize on the technologies underneathmicroalgae-to-biofuels systems, concentrating on the biomass production,improvement in algae for increasing yield, processing and the extraction ofbiofuels.