Techno-economic Assessment of Pretreatment of Lignocellulosic Date Palm (Phoenix dectylifera L.) Residues

  • Chuanji Fang

Student thesis: Doctoral Thesis

Abstract

High worldwide demand for energy and concern over global climate change have led to a resurgence in the development of alternative energy. Geopolitical factors have strongly driven the research in biofuel and value-added products from lignocellulosic biomass, as has commercialization of cellulosic biofuels in North and South America, Europe, and China. However, the bioprocessing of lignocellulosic biomass native in the Middle East is still in its infancy. In this thesis, lignocellulosic date palm (Phoenix dactylifera L.) residues native in the UAE with bioenergy potentials was used as the biorefinery feedstock. Technoeconomic evaluations of leading hydrothermal, novel seawater-based, and new combined hydrothermal and deep eutectic solvents (DESs) pretreatment were performed. These pretreatment technologies were additionally evaluated based on energy return on investment (EROI), and alignment to UAE's energy policy. Although hydrothermal pretreatment showed promising potential in processing lignocellulosic date palm residues because of the production of high enzymatically digestible and fermentable solids, and low toxic pretreatment liquids to the yeast (Saccharomyces cerevisiae) in this study, high water consumption (1.9-5.9 m3 water/m3 of biofuel) required by a biomass processing plant is a major concern in the arid regions. The technical feasibility of using seawater as the alternative to fresh water was validated in this thesis. A novel approach of combining hydrothermal and DESs treatment proposed in this thesis showed significant enhancement of enzymatic digestibility of biomass (1.7 times of that obtained when using hydrothermal pretreatment only). Techno-economic analyses show that the biorefinery process using seawater-based pretreatment has higher total capital investment (TCI) but lower annual operating cost (AOC), resulting in more net profit compared with that when using hydrothermal pretreatment. Moreover, energy return on investment (EROI) for biorefinery process using seawaterbased pretreatment (1.08:1) is only slightly lower than that when using hydrothermal pretreatment (1.13:1). Based on the studies in this thesis, the alignments of cellulosic biorefinery development with UAE Vision 2021 were proposed: 1) Date palm residues is a good lignocellulosic biomass native in the UAE for renewable energy production; 2) Biorefinery using seawater shows promising potential to substitute that using fresh water in coastal and arid areas like UAE.
Date of AwardMay 2017
Original languageAmerican English

Keywords

  • Date palm residues
  • Hydrothermal pretreatment
  • Seawater
  • Deep Eutectic
  • Solvents (DESs)
  • Bioethanol
  • Biorefinery
  • Techno-economic analysis.

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