XIAODAN WU, RONGSHENG RUAN, ZHENYI DU, and YUHUAN LIU

1.1 INTRODUCTION

In recent years, increasing consumption of conventional energy has caused serious concerns about energy security and environmental degradation. Therefore, renewable, non-polluting biomass energy has been receiving more and more attention from both the academic community and indus­tries. Biomass derived from photosynthesis includes a variety of organ­isms, such as plants, animals and microbes. As photosynthetic microor­ganisms, microalgae can use and therefore remove nitrogen, phosphorus in wastewater, sequester CO2 in the air, and synthesize lipids which can be converted into biodiesel. The declining supply of conventional fossil fuel and concern about global warming make microalgae-based biodiesel a very promising alternative. Although the potential and advantages of microalgae-based biodiesel over conventional biodiesel have been well recognized [1-3], broad commercialization of microalgae biodiesel has not yet to be realized, chiefly because of the techno-economic constraints, particularly in the areas of mass cultivation and downstream processing. The objectives of the present paper are to review recent development in microalgae production, especially in high density cultivation and down­stream processing, and identify technological bottlenecks and strategies for further development.