Microalgae to biofuels: 'Promising' alternative and renewable energy, review

The rapid growth of human population has led to mounting energy demands, which is projected to increase by 50% or more by 2030. The natural petroleum can not catch-up the current consumption rate, which is already reported to be 105 times faster than nature can create. Besides, the use of fossil fuels is devastating to our environment through greenhouse gas emissions and consequent global warming. Therefore, the search for 'clean' energy has become the most overwhelming challenges. Currently, several alternatives are being studied and implemented. Biofuels, fuels from living organisms, provide environmental benefits, since their use leads to a decrease in the harmful emissions of CO2 and hydrocarbons and, to the elimination of SOx emissions, with a consequent decrease in the greenhouse effects. Unfortunately, the present biofuel projections are based on feed-stocks that are also food commodities and resources suitable for conventional agriculture. One possibility to overcome the problem is the cultivation of micro-algae and switching to third generation biofuels, which seem to be a promising source since algae are able to efficiently convert sunlight, water, and CO2 into a variety of products suitable for renewable energy applications. Therefore, this review is intended to recapitulate current works on micro-algal biofuel production potential and discuss possible ways to put it into practice. This review starts by highlighting the advantages and various forms of micro-algal biofuels. Some of the micro-algal species proved to be suitable for biofuel production so far are considered, with particular emphasis on Scenedesmus obliquus. The recent attempts and achievements in improving the economies of production through genetic and metabolic engineering of micro-algal strains are also addressed. Other potential applications such as wastewater treatment and CO2 mitigation that can be coupled with biofuel production are described. Finally, the promises and challenges of algae to biofuel industry are uncovered.