Accepted 16th November, 2014
As the world hunts eagerly for alternative fuel sources, microalgae are attracting wide interest. Lipids derived from algae hold great promise as a biofuel feedstock. The high-lipid content found in some species is a fundamental edge. So are algae’s high per-acre productivity and its ability in thriving in areas not already used for food production. Therefore, there are vigorous research initiatives aimed to develop alternative renewable and potentially carbon neutral solid, liquid and gaseous biofuels as alternative energy resources. However, alternate energy resources akin to first generation biofuels derived from terrestrial crops such as sugar beet, sugarcane, rapeseed and maize place an enormous strain on world food markets, contribute to water shortages and precipitate the destruction of the world’s forests. Second generation biofuels derived from lignocellulosic agriculture and forest residues; however there is a serious concern over competing land use or required land use changes. Therefore, on the base of current knowledge and technology projections, third generation biofuels specifically derived from microalgae are considered to be a technically viable alternative energy resource that is devoid of the major drawbacks associated with first and second generation biofuels. Microalgae are photosynthetic microorganisms with very simple growing requirements (sugars, light, N, P, CO2, and K) that can produce lipids, proteins and carbohydrates in large amounts over short periods of time. These products can be processed into both biofuels and valuable co-products. This study reviewed the technologies underpinning microalgae-to-biofuels systems, focusing on the biomass production, harvesting, conversion technologies, and the extraction of useful co-products. It also reviewed the synergistic pairing of microalgae propagation with carbon sequestration and wastewater treatment potency for mitigation of environmental impacts associated with energy conversion and utilisation. It was found that, whereas there are outstanding issues related to photosynthetic efficiencies and biomass output, microalgae-derived biofuels could progressively substitute a significant proportion of the fossil fuels required to meet the growing energy demand.
Key words: Bioenergy conversion, biomass recovery, photobioreactor, microalgae