Valorization of Mixed Lignocellulosic Residues in the UAE using a Biorefinery Concept

  • Muhammad Tahir Ashraf

Student thesis: Doctoral Thesis

Abstract

Envisioning a biorefinery in an arid region, like the UAE, starts with the challenge of a sustainable supply of biomass feedstock. Biorefinery based on multi-feedstock lignocellulosic residues can be viable where the sustainable supply of a single substrate is limited. Lignocellulosic residues can be obtained from trees, grasses, and agricultural crops and are non-food biomass, categorized as second generation feedstocks. For the prospects of a biorefinery in the UAE, this study has focused on utilizing UAE's local lignocellulosic residues. Lignocellulosic residues selected here are date palm fronds, trimmings of Bermuda grass, and trimmings of Jasmine hedges. Different lignocellulosic residues vary in composition and anatomical features and there is a lack of knowledge about the technical and economic feasibility of processing the multi-specie lignocellulosic residues in a biorefinery concept. First part of this study attempts to fill this knowledge gap by experimental validation of the multi-specie lignocellulose processing in the framework of biochemical pathway biorefinery. Then, an economic evaluation is made to highlight the best processing approach for the multi-feedstock lignocellulose to produce monomeric sugars (C6+C5). Sugar monomers are intermediate chemicals and precursor to a range of products via chemical and biochemical processing. Targeting an intermediate product splits the biorefinery process into modules. This modular approach of focusing on sugar platform makes the results of this study applicable for the both fuel (ethanol) and non-fuel applications. Bioprocessing of lignocellulosic feedstock to produce marketable products constitutes a series of processing steps. There are several technological options available for each of the processing steps. Finding the best series of technologies and marketable product is a process network synthesis (PNS) problem. Due to processing complexity and geologically disperse feedstock availability and product market, it might be feasible to distribute the biorefining process into different sections operated by independent companies or actors. A conventional biorefinery process, analogues to an oil refinery, decomposes feedstock to intermediate platform chemicals, and then these chemicals are upgraded to marketable products. A biorefinery can be naturally decomposed on the basis of intermediate platform chemicals, where independent companies produce the intermediate platform chemicals and separate companies utilize the intermediates to produce marketable products. In such a scenario most of the intermediate chemicals will be a new entrant to the market, and establishing their market price is imperative for a feasible synthesis of the overall biorefinery. The conventional PNS solution approaches do not take into account this feature that each technology or processing step is operated as a separate company. However, for the described distributed manufacturing scenario a framework is needed that takes into account the competing economics of the interacting actors and assigns the feasible price to the new entrant intermediate chemicals. In the second part of this study, a game theory based framework is developed to solve this PNS problem and to evaluate the price of intermediate products, where the biorefinery process is carried out by independent multiple companies with competing economics.
Date of AwardDec 2017
Original languageAmerican English

Keywords

  • biorefinery process
  • sustainable supply
  • lignocellulosic residues
  • multi-feedstock lignocellulose.

Cite this

'