ABSTRACT
Rapid growth of population coupled with urbanization and industrialization is responsible for a high degree of environmental deterioration due to excessive consumption of fossil fuels. The emission of greenhouse gases, a natural consequence of the combustion of fossil fuels, can further exacerbate the situation because it can stimulate a global climate transformation and also cause adverse effects on human health. Consequently, development of clean, renewable, and sustainable alternative energy sources has garnered widespread attention across research communities. Among the potential renewable energy resources, eco-friendly biofuels hold a high degree of promise. Extracts or derivatives from a plethora of edible and nonedible crops, for instance soybeans, vegetable oils, animal fats, and agricultural and forest wastes, have been exploited for biofuel production. In spite of this, concerns such as competition with food crops and the usage of cultivable land for the production of first- and second-generation biofuel feedstocks persist. This necessitates and signifies the applicability of the third-generation biofuels, specifically derived from microalgae, which have been touted to be viable and promising feedstocks for biofuel production. The fact that microalgae have higher growth rates due to their high photosynthetic efficiencies ensures high yields of lipid oil and high biodiesel productivity, and thus pose a distinct advantage over other feedstocks. In the context of environmental issues, microalgae can mitigate the land-usage challenge to a great extent and hence alleviate subsequent deforestation, loss of biodiversity, and environmental pollution. Here, we review the in-place process technologies for biofuels production, including cultivation and harvesting technologies for microalgae biomass production, and conversion technologies from microalgal biomass to biofuels. Furthermore, we focus on the biochemical characteristics of various algal species, as well as the production of biodiesel, bioethanol, and biogas from algae biomass. This chapter collates useful information that may drive development of feasible, economical, and efficient technologies for biofuel production from microalgae with an eye on the coming era. Also, few recommendations are made for additional improvements in biofuel production technologies from microalgae in order to achieve economic feasibility for pilot-scale industrial applications.
