Dr Kok Siew Ng

Kok Siew Ng

Research Fellow



Kok Siew Ng joined the Centre for Environmental Strategy as Research Fellow in May 2015. His current research project is primarily focused on resource recovery from wastewater using bioelectrochemical systems. The project is funded by Natural Environment Research Council (NERC) and led by Dr. Jhuma Sadhukhan. This multidisciplinary project is carried out in partnership with academic institutions (Newcastle University, University of South Wales and The University of Manchester) and industrial companies (Tata Steel and Magneto).

Kok Siew completed his MEng Chemical Engineering with Chemistry at the University of Manchester in 2008. He later gained his PhD from the Centre for Process Integration (CPI), The University of Manchester in 2011. Kok Siew has industrial experience as a consultant in Process Integration Limited, UK, 2011-2013. He has involved in a diverse range of consultancy projects in the UK, Europe and China including refrigeration system for LNG processes, upgrading of gasoline feedstock into chemicals, water system integration in refinery and steel plant. He had also taken up a lead role in an EU-funded project on water system in steel plant. Kok Siew's expertise lies predominantly in conceptual process design, process integration, simulation modelling, techno-economic analysis and optimisation.

Kok Siew is the co-author of the advanced engineering textbook, “Biorefineries and Chemical Processes: Design, Integration and Sustainability Analysis”, published by Wiley in 2014. He was awarded the IChemE Junior Moulton Medal in 2011 for the best publication for his work on clean coal technologies.

Research interests

My research interests cover a broad range of chemical engineering fields:

  • Resource recovery and utilisation from waste
  • Biorefinery systems design and integration
  • Cogeneration and Polygeneration through thermochemical platform (gasification, pyrolysis, Fischer-Trospch and methanol synthesis, CHP)
  • Clean coal technologies
  • Carbon dioxide utilisation
  • Energy integration


Research Activities

  • A member of the organizing committee for biorefinery research workshop funded by British Council and CONACyT, 18th-22nd May 2015, Instituto Mexicano del Petróleo, Mexico City, Mexico.
  • Guest Editor of special issue journal on Biorefinery Value Chain Creation in Chemical Engineering Research and Design (IChemE journal), 2015
  • Guest Editor of special issue journal on Sustainable Availability and Utilisation of Wastes in Sustainable Production and Consumption (IChemE journal), 2015.
  • Co-supervised a PhD student for an industrial based research project related to water system integration in the steel plant, 2012-2013.
  • Co-supervised a PhD student for a sago starch biorefinery project (collaborating with University of Nottingham Malaysia), 2014.





IChemE Junior Moulton Medal “Ng, K.S., Lopez, Y., Campbell, G.M., Sadhukhan, J., 2010. Heat integration and analysis of decarbonised IGCC sites. Chem Eng Res Des., 88 (2): 170-188.”



Overseas Research Scholarship (ORS), Manchester Alumni Funds, Process Integration Research Consortium (PIRC) Research Funds, School of Chemical Engineering and Analytical Science Scholarship


The School of Chemical Engineering and Analytical Science Postgraduate Conference Poster Competition - 3rd Prize (PhD Year 1 category)


MEng Chemical Engineering with Chemistry Specialist Subject Course Prize

My publications


Ng KS, Zhang N, Sadhukhan J (2013) Techno-economic analysis of polygeneration systems with carbon capture and storage and CO2 reuse, Chemical Engineering Journal 219 pp. 96-108
Several decarbonised polygeneration schemes exploiting carbon capture and storage (CCS) or CO2 reuse technologies for the generation of clean fuels, chemicals, electricity and heat have been systematically analysed for techno-economic feasibility. Process simulation, energy integration and economic analysis were undertaken to analyse the effect of process configurations and operating conditions on the economic potential (EP) and risks. CO2 capture and reuse producing methane using Sabatier's reaction shows less favourable economics compared to the counterpart CCS based scheme, both producing electricity, hydrogen, acetic acid and methanol in common. Post-combustion CO2 tri-reforming into methanol production in addition to electricity generation shows overall favourable economics compared to the counterpart integrated gasification combined cycle (IGCC) with CCS scheme. Thus, increasing product portfolio from energy products in a cogeneration plant to chemical products evolved from thermodynamic and process integration synergies increases the techno-economic viability. Bio-oil can be processed as an alternative low carbon feedstock. While bio-oil creates environmental incentives, its economic competitiveness can be enhanced by introducing credits on product prices. © 2013 Elsevier B.V.
Wan YK, Sadhukhan J, Ng KS, Ng DKS (2015) Techno-economic evaluations for feasibility of sago-based biorefinery, Part 1: Alternative energy systems, CHEMICAL ENGINEERING RESEARCH & DESIGN 107 pp. 263-279 INST CHEMICAL ENGINEERS
Ng KS, Lopez Y, Campbell GM, Sadhukhan J (2010) Heat integration and analysis of decarbonised IGCC sites, CHEMICAL ENGINEERING RESEARCH & DESIGN 88 (2A) pp. 170-188 INST CHEMICAL ENGINEERS
Design of clean energy systems is highly complex due to the existence of a variety of CO 2 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 flowsheet configurations with different decarbonisation strategies. The fundamental aspect of the proposed methodology lies in thermodynamic feasibility assessment as well as quantification of CO 2 emission treatment intensity using a graphical approach (CO 2 emission balance diagram) for energy and economic performance analyses of integrated decarbonised systems. The relationship between the graphical representation 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 polygeneration and cogeneration systems, incorporating either of carbon capture and storage (CCS) or CO 2 reuse options. © 2012 Elsevier Ltd.
Sadhukhan J, Ng KS, Shah N, Simons HJ (2009) Heat Integration Strategy for Economic Production of Combined Heat and Power from Biomass Waste, ENERGY & FUELS 23 pp. 5106-5120 AMER CHEMICAL SOC
Ng K, Martinez Hernandez E (2016) A systematic framework for energetic, environmental and economic (3E) assessment and design of polygeneration systems, Chemical Engineering Research and Design 106 pp. 1-25 Elsevier
The replacement of traditional process design approach by a more holistic approach is exigent in view of developing sustainable industrial systems and effectively reducing the energy and emission intensities in the process industries. Polygeneration systems are flexible and integrated multi-product systems that can potentially enhance energy efficiency, minimise financial risk and mitigate environmental impact. This paper presents a systematic conceptual process design and decision-making framework for facilitating multi-criteria analysis and selection of design options by considering three major criteria at process level?energy, environment and economy (3E). In this framework, three major steps are carried out: (i) defining system boundary, (ii) performance evaluation on the inner and outer system boundaries, (iii) 3E performance evaluation. 3E metric is proposed and it is derived from the relative economic worthiness associated with process energy intensity, greenhouse gas intensity and energy recovery which collectively indicates the techno-economic and environmental performances of a system with respect to the base case system. The methodology has been demonstrated through methanol and electricity production system with eight alternative configurations. Among the configurations under consideration, high offgas recycle for methanol production followed by electricity generation in series configuration has been found to carry the best 3E performance.
Sadhukhan J, Ng KS (2011) Economic and European Union Environmental Sustainability Criteria Assesment of Bio-Oil-Based Biofuel Systems: Refinery Integration Cases, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 50 (11) pp. 6794-6808 AMER CHEMICAL SOC
Ng KS, Zhang N, Sadhukhan J (2012) Decarbonised coal energy system advancement through CO 2 utilisation and polygeneration, Clean Technologies and Environmental Policy 14 (3) pp. 443-451
Development of clean coal technology is highly envisaged to mitigate the CO 2 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 CO 2 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 317 M¬/y (3.6 ¬/GJ). The results have demonstrated promising prospects of employing CO 2 reuse technology into IGCC system, as an alternative to CCS system. © 2011 Springer-Verlag.
Ng KS, Sadhukhan J (2011) Techno-economic performance analysis of bio-oil based Fischer-Tropsch and CHP synthesis platform, BIOMASS & BIOENERGY 35 (7) pp. 3218-3234 PERGAMON-ELSEVIER SCIENCE LTD
Sadhukhan J, Ng KS, Martinez Hernandez E (2014) Biorefineries and Chemical Processes: Design, Integration and Sustainability Analysis, pp. 1-625 Wiley
As the range of feedstocks, process technologies and products expand, biorefineries will become increasingly complex manufacturing systems. Biorefineries and Chemical Processes: Design, Integration and Sustainability Analysis presents process modelling and integration, and whole system life cycle analysis tools for the synthesis, design, operation and sustainable development of biorefinery and chemical processes.

Topics covered include:

Introduction: An introduction to the concept and development of biorefineries.

Tools: Included here are the methods for detailed economic and environmental impact analyses; combined economic value and environmental impact analysis; life cycle assessment (LCA); multi-criteria analysis; heat integration and utility system design; mathematical programming based optimization and genetic algorithms.

Process synthesis and design: Focuses on modern unit operations and innovative process flowsheets. Discusses thermochemical and biochemical processing of biomass, production of chemicals and polymers from biomass, and processes for carbon dioxide capture.

Biorefinery systems: Presents biorefinery process synthesis using whole system analysis. Discusses bio-oil and algae biorefineries, integrated fuel cells and renewables, and heterogeneous catalytic reactors.

Companion website: Four case studies, additional exercises and examples are available online, together with three supplementary chapters which address waste and emission minimization, energy storage and control systems, and the optimization and reuse of water.

This textbook is designed to bridge a gap between engineering design and sustainability assessment, for advanced students and practicing process designers and engineers.

Sadhukhan J, Martinez-Hernandez E, Murphy R, Ng D, Hassim M, Ng K, Kim W, Jaye I, Leung M, Hang P, Andiappan V (2017) Role of Bioenergy, Biorefinery and Bioeconomy in Sustainable Development: Strategic Pathways for Malaysia, Renewable & Sustainable Energy Reviews 81 (Part 2) pp. 1966-1987 Elsevier
Malaysia has a plethora of biomass that can be utilized in a sustainable manner to produce bio-products for circular green economy. At the 15th Conference of Parties in Copenhagen, Malaysia stated to voluntarily reduce its emissions intensity of gross domestic product by upto 40% by 2020 from 2005 level. Natural resources e.g. forestry and agricultural resources will attribute in achieving these goals. This paper investigates optimum bio-based systems, such as bioenergy and biorefinery, and their prospects in sustainable development in Malaysia, while analyzing comparable cases globally. Palm oil industry will continue to play a major role in deriving products and contributing to gross national income in Malaysia. Based on the current processing capacity, one tonne of crude palm oil (CPO) production is associated with nine tonnes of biomass generation. Local businesses tend to focus on products with low-risk that enjoy subsidies, e.g. Feed-in-Tariff, such as bioenergy, biogas, etc. CPO biomass is utilized to produce biogas, pellets, dried long fibre and bio-fertilizer and recycle water. It is envisaged that co-production of bio-based products, food and pharmaceutical ingredients, fine, specialty and platform chemicals, polymers, alongside biofuel and bioenergy from biomass is possible to achieve overall sustainability by the replacement of fossil resources. Inception of process integration gives prominent innovative biorefinery configurations, an example demonstrated recently, via extraction of recyclable, metal, high value chemical (levulinic acid), fuel, electricity and bio-fertilizer from municipal solid waste or urban waste. Levulinic acid yield by only 5 weight% of waste feedstock gives 1.5 fold increase in profitability and eliminates the need for subsidies such as gate fees paid by local authority to waste processor. Unsustainable practices include consumable food wastage, end-of-pipe cleaning and linear economy that must be replaced by sustainable production and consumption, source segregation and process integration, and product longevity and circular economy.
Ng K, Head I, Premier G, Scott K, Yu E, Lloyd J, Sadhukhan J (2016) A Multilevel Sustainability Analysis of Zinc Recovery from Wastes, Resources, Conservation & Recycling 113 pp. 88-105 Elsevier
As waste generation increases with increasing population, regulations become stricter to control and mitigate environmental emissions of substances, e.g. heavy metals: zinc and copper. Recovering these resources from wastes is the key interest of industries. The objective of this paper is the sustainability and feasibility evaluations of zinc recovery from waste streams. Sustainability and feasibility of a resource recovery strategy from wastes in a circular economy are governed by avoided environmental impacts and cost-effective transformation of an environmental contaminant into a valuable resource, e.g. as a coproduct by making use of an existing infrastructure as much as possible. This study, for the first time, gives a comprehensive overview of secondary sources and processes of recovering zinc, its stock analysis by country, regional and global divisions by a Sankey diagram, policies to regulate zinc emissions and avoided environmental impacts by zinc recovery. Two representative cases are further investigated for economic feasibility analysis of zinc recovery from 1) steelmaking dust and (2) municipal solid waste (MSW). The amount and value of zinc that can be generated from dust emitted from various steelmaking technologies are estimated. Additional revenues for the steelmaking industrial sector (with electric arc furnace), at the plant, national (UK), regional (EU) and global levels are 11, 12, 169 and 1670 million tonne/y, or 19-143, 20-157, 287-2203 and 2834-21740 million ¬/y, respectively. The second case study entails an integrated mechanical biological treatment (MBT) system of MSW consisting of metal recovery technologies, anaerobic digestion, refuse derived fuel (RDF) incineration and combined heat and power (CHP) generation. An effective economic value analysis methodology has been adopted to analyse the techno-economic feasibility of the integrated MBT system. The value analysis shows that an additional economic margin of 500 ¬ can be generated from the recovery of 1 tonne of zinc in the integrated MBT system enhancing its overall economic margin by 9%.