title: An energy analysis of torrefaction for upgrading microalga residue as a solid fuel.
abstract: The torrefaction characteristics and energy utilization of microalga Chlamydomonas sp. JSC4 (C. sp. JSC4) residue under the combination of temperature and duration are studied by examining contour maps. The torrefaction temperature on the contour line of solid yield has a trend to linearly decrease with increasing duration. An index of relative energy efficiency (REE) is introduced to identify the performance of energy utilization for upgrading biomass. For a fixed energy yield, the optimal operation can be found to maximize the heating value of the biomass and minimize the solid yield. The energy utilization under the combination of a high temperature and a short duration is more efficient than that of a low temperature and a long duration. The maximum REE along the contour line of energy yield is always exhibited at the highest temperature (300°C) where the energy efficiency can be enlarged by a factor of at least 2.36.
authors.affiliation: Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan, ROC. Electronic address: weihsinchen@gmail.com.
authors.forename: Wei-Hsin
authors.initials: WH
authors.lastname: Chen
authors.affiliation: Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan, ROC.
authors.forename: Ming-Yueh
authors.initials: MY
authors.lastname: Huang
authors.affiliation: Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC; Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan, ROC; Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC.
authors.forename: Jo-Shu
authors.initials: JS
authors.lastname: Chang
authors.affiliation: Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan, ROC.
authors.forename: Chun-Yen
authors.initials: CY
authors.lastname: Chen
authors.affiliation: Department of Environmental Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC.
authors.forename: Wen-Jhy
authors.initials: WJ
authors.lastname: Lee
mesh_terms: D056804:Biofuels; D018533:Biomass; D001709:Biotechnology / Q000379:methods; D002696:Chlamydomonas / Q000378:metabolism; D058086:Microalgae / Q000378:metabolism*; D013696:Temperature; D013816:Thermodynamics; D013818:Thermogravimetry
chemical_list: D056804:Biofuels
keywords: Contour map; Energy analysis; Microalga residue; Relative energy efficiency; Torrefaction