title: Advances in direct transesterification of algal oils from wet biomass.
abstract: An interest in biodiesel as an alternative fuel for diesel engines has been increasing because of the issue of petroleum depletion and environmental concerns related to massive carbon dioxide emissions. Researchers are strongly driven to pursue the next generation of vegetable oil-based biodiesel. Oleaginous microalgae are considered to be a promising alternative oil source. To commercialize microalgal biodiesel, cost reductions in oil extraction and downstream biodiesel conversion are stressed. Herein, starting from an investigation of oil extraction from wet microalgae, a review is conducted of transesterification using enzymes, homogeneous and heterogeneous catalysts, and yield enhancement by ultrasound, microwave, and supercritical process. In particular, there is a focus on direct transesterification as a simple and energy efficient process that omits a separate oil extraction step and utilizes wet microalgal biomass; however, it is still necessary to consider issues such as the purification of microalgal oils and upgrading of biodiesel properties.
authors.affiliation: Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343, Republic of Korea. Electronic address: yearn@kier.re.kr.
authors.forename: Ji-Yeon
authors.initials: JY
authors.lastname: Park
authors.affiliation: Advanced Biomass R&D Center, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors.forename: Min S
authors.initials: MS
authors.lastname: Park
authors.affiliation: Department of BioNano Technology, Gachon University, 1342 Seongnamdae-ro, Sujeong-gu, Seongnam-si, Gyeonggi-do 461-701, Republic of Korea.
authors.forename: Young-Chul
authors.initials: YC
authors.lastname: Lee
authors.affiliation: Advanced Biomass R&D Center, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors.forename: Ji-Won
authors.initials: JW
authors.lastname: Yang
mesh_terms: D018533:Biomass; D004734:Energy Metabolism; D004951:Esterification; D058086:Microalgae / Q000378:metabolism*; D009821:Oils / Q000378:metabolism*; D014867:Water / Q000737:chemistry*
chemical_list: D009821:Oils; D014867:Water
keywords: Biodiesel; Direct transesterification; Energy balance; Wet microalgae; Wet oil extraction