Current status and challenges on microalgae-based carbon capture

Worldwide concern on the negative effect of climate change towards human and environment has synergized the development of CO2 capture technologies. Currently, culturing of microalgae for CO2 bio-fixation has gained a huge momentum due to their high photosynthetic rate that allows bio-fixation of CO2 more efficient than terrestrial plants. In addition, lipid from microalgae biomass can be converted to biodiesel; a renewable fuel that emits less CO2 compared to fossil-diesel when combusted. However, several recent life cycle assessment (LCA) studies have revealed that enormous energy input is required to cultivate microalgae and also for the harvesting and drying processes. The energy required (in the form of electricity) is normally generated from burning coal or natural gas that emits substantial amount of CO2 to the atmosphere and this could entirely eliminate all the positive effect of culturing microalgae for CO2 bio-fixation and biofuel production. Thus, in this review, critical assessment and comparative study of CO2 bio-fixation rate by microalgae and CO2 emission rate during cultivation and processing of microalgae biodiesel were carried out. In addition, the prospects and limitations of using flue gas to culture microalgae and several possible strategies to enhance CO2 utilization by microalgae will also be discussed extensively. (c) 2012 Elsevier Ltd. All rights reserved.