Kok Siew Ng

Novel integrated mechanical biological chemical treatment (MBCT) systems for the production of levulinic acid from fraction of municipal solid waste: A comprehensive techno-economic analysis.

This paper, for the first time, reports integrated conceptual MBCT/biorefinery systems for unlocking the value of organics in municipal solid waste (MSW) through the production of levulinic acid (LA by 5wt%) that increases the economic margin by 110-150%. After mechanical separation recovering recyclables, metals (iron, aluminium, copper) and refuse derived fuel (RDF), lignocelluloses from remaining MSW are extracted by supercritical-water for chemical valorisation, comprising hydrolysis in 2wt% dilute H2SO4 catalyst producing LA, furfural, formic acid (FA), via C5/C6 sugar extraction, in plug flow (210-230°C, 25bar, 12s) and continuous stirred tank (195-215°C, 14bar, 20min) reactors; char separation and LA extraction/purification by methyl isobutyl ketone solvent; acid/solvent and by-product recovery. The by-product and pulping effluents are anaerobically digested into biogas and fertiliser. Produced biogas (6.4MWh/t), RDF (5.4MWh/t), char (4.5MWh/t) are combusted, heat recovered into steam generation in boiler (efficiency: 80%); on-site heat/steam demand is met; balance of steam is expanded into electricity in steam turbines (efficiency: 35%).

Decarbonised coal energy system advancement through CO2 utilisation and polygeneration

Development of clean coal technology is highly envisaged to mitigate the CO2 emission level whilst meeting the rising global energy demands which require highly efficient and economically compelling technology. Integrated gasification combined cycle (IGCC) with carbon capture and storage (CCS) system is highly efficient and cleaner compared to the conventional coal-fired power plant. In this study, an alternative process scheme for IGCC system has been proposed, which encompasses the reuse of CO2 from the flue gas of gas turbine into syngas generation, followed by methanol synthesis. The thermodynamic efficiency and economic potential are evaluated and compared for these two systems. The performances of the systems have been enhanced through systematic energy integration strategies. It has been found that the thermodynamic and economic feasibilities have attained significant improvement through the realisation of a suitably balanced polygeneration scheme. The economic potential can be enhanced from negative impact to 317xa0M€/y (3.6xa0€/GJ). The results have demonstrated promising prospects of employing CO2 reuse technology into IGCC system, as an alternative to CCS system.

A graphical CO2 emission treatment intensity assessment for energy and economic analyses of integrated decarbonised production systems

a b s t r a c t Design of clean energy systems is highly complex due to the existence of a variety of CO2 abatement and integration options. In this study, an effective decision-making methodology has been developed for facilitating the selection of lowest energy or lowest cost intensity systems, from a portfolio of flow- sheet configurations with different decarbonisation strategies. The fundamental aspect of the proposed methodology lies in thermodynamic feasibility assessment as well as quantification of CO2 emission treatment intensity using a graphical approach (CO2 emission balance diagram) for energy and economic performance analyses of integrated decarbonised systems. The relationship between the graphical rep- resentation and performances is established using blocks and boundaries on integrated systems. The effectiveness of the methodology has been demonstrated through a range of coal gasification based poly- generation and cogeneration systems, incorporating either of carbon capture and storage (CCS) or CO2 reuse options.

Value-Added Products from Wastes Using Extremophiles in Biorefineries: Process Modeling, Simulation, and Optimization Tools

This chapter provides an overview of value-added production using extremophiles as well as the advantages and challenges for process development in a biorefinery concept. The chapter then shows a modeling framework that includes metabolic flux modeling, growth kinetics, and bioreactor models as well as process simulation. The model results are the basis for optimization, economic analysis, and life cycle assessment. The tools are applied to the production of poly-3-hydroxybutyrate (PHB) by using the halophilic bacteria Halomonas sp. The results highlighted the importance of relating models at the various scales and to look at the whole process picture to optimize the economic and environmental performances of the resulting biorefinery process. In the optimized process, the minimum PHB selling price was

Design of biorefinery systems for conversion of corn stover into biofuels using a biorefinery engineering framework

7.05 per kg and the reduction in greenhouse gas emissions was 90%, with 0.708 kg CO-eq per kg of PHB. These results showed the potential for using halophilic bacteria to make PHB production competitive in terms of economics and environmental impacts. This also shows how extremophile processing will play a key role in making biorefineries more profitable and sustainable.

Process integration and economic analysis of bio-oil platform for the production of methanol and combined heat and power

Unlocking the potential and value of lignocellulosic residues is an important step in making biorefineries economically and environmentally promising. This calls for a holistic and systematic approach in designing sustainable industrial systems. In this work, biorefinery systems via biochemical route (acetone–butanol–ethanol or ABE system) and thermochemical route (gasification and mixed alcohols or GMA system) for converting corn stover into biofuels have been designed using a Sustainable Engineering Framework. The framework involves eight main steps: (1) design problem definition, (2) data collection, (3) process synthesis and simulation, (4) process integration, (5) resource recovery from residues, (6) utility system design, (7) economic and environmental modelling and (8) economic value and environmental impact margin analysis for decision making. Consideration of resource recovery from biorefinery waste streams has proven to be the key in making biorefineries self-sustaining and withxa0low environmental impacts. Simultaneous economic and environmental feasibility assessment at the early stage of process design is highly envisaged. The cost of biofuel production in the ABE system has been found to be 49.2 US

Techno-economic performance analysis of bio-oil based Fischer-Tropsch and CHP synthesis platform

/GJ and 69.9 US

Techno-economic analysis of polygeneration systems with carbon capture and storage and CO2 reuse

/GJ in the GMA system. The greenhouse gas emissions are 46.2xa0gxa0CO2-eq/GJ for ABE and 19.0xa0gxa0CO2-eq/GJ for GMA, lower than gasoline (85xa0gxa0CO2-eq/GJ). The GMA system is not economically compelling though with high environmental benefit, while the ABE system has shown to be both economically and environmentally feasible.