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The aviation sector is looking to replace conventional metals for aircraft structures with composite materials due to the latter's potentially favourable combination of mechanical properties and low weight. However, relatively little is known about the environmental impacts and economic costs associated with composite materials displacing conventional metal in aircraft applications, and the relevant analysis models have not been well established. An integrated life cycle assessment (LCA) and life cycle costing (LCC) framework is proposed for assessing environmental and cost performances. The framework and relevant analysis models developed provide a systematic assessment of environmental and economic respective aspects associated with a given product or process. A graphical tool was developed to represent an eco-efficiency (EE) comparison based on the integration of the LCA and LCC results, which is a sustainability measure combining environmental and economic performances for comparing the different alternatives to support material selection. The displacement of a conventional aluminium aircraft door by a composite door on a life cycle basis is presented as an example of the use of this framework. The scenario analysis, sensitivity analysis and Monte Carlo Simulation as support analyses are carried out to address the data uncertainty. The graphical visualisation tool demonstrates the integrated environmental and economic performances of this displacement. The research found that composite aircraft doors could increase both environmental and financial impacts by 77% over conventional doors across the entire life cycle. The study recommended that the composite door would become favoured if a weight reduction of 45% could be achieved for the future composite door after optimisation and continuous improvement. The EE analysis result demonstrated that, among all the composite door scenarios with various composite waste recycling methods, the pyrolysis recycling with equal quality carbon fibre substitution scenario presented the best environmental and economic performances. This study presents the pioneering application of a comprehensive framework for analysing aircraft components, while also introducing novel cost and environmental impact models. Notably, this research focuses on addressing the end-of-life recycling challenges specific to composites. This study contributes a new database for inventory datasets and demonstrates a potential improvement method for future aircraft door production. The research looks at the whole aircraft supply chain with a holistic view of the materials and processes, providing a better understanding of the trade-offs and achieving sustainable decisions.

Bahrain was the first Gulf Cooperation Country (GCC) to discover oil. Since then, oil has become the keystone of the country's economic development, reflecting on all sectors, particularly power generation. This underlines the difficulty of shifting from well-established oil-based power production to renewable energy. Nevertheless, a significant milestone was achieved in January 2017, when the Sustainable Energy Unit (SEU) launched the National Renewable Energy Action Plan (NREAP). The plan sets the roadmap for identifying the most appropriate renewable resources for Bahrain and its best technologies. Special attention should be paid to Sustainable Generation Expansion Planning (GEP) for Bahrain's electrical system with renewables. This is because Bahrain's government is committed to the Sustainable Development Goals (SDG) and has incorporated them into its action plan since 2015. The sustainability theme in the energy system interacts with different research areas, and it requires a multidimensional approach to cover its impact on the national grid, environment, economy and other sectors. This study aims to assist Bahrain's policymakers in evaluating the renewable energy technologies for sustainable growth of the generation sector by suggesting an Intelligent Decision Support System (IDSS) based on a combination of the Analytical Hierarchy Process (AHP) and Artificial Neural Networks (ANN). After evaluating the derived indicators from seventy-three studies by experts and applying the selection principles, fifteen indicators are selected for constructing the AHP model. The AHP model outcomes revealed that wind turbines are the most appropriate technology for Bahrain. Then, the ANN model is structured based on the generated cases from the AHP model. The Levenberg-Marquardt algorithm is used for processing the data with a hyper tangent sigmoid and a linear function for the hidden layer and output layer of the ANN model. The scenario analysis demonstrates that the IDSS can be used with confidence to explore the effect of each criterion and sub-criterion on the sustainable growth of the electrical grid in Bahrain.

Life cycle Assessments (LCAs) of crude oil derived products such as fuels, petrochemicals and polymers benefit from robust inventories of emissions and consumptions of the specific ways in which the crude oil can be extracted and processed. It is known that there is variation of up to 30% or more in the Greenhouse gas (GHG) ‘footprint’ of different crude oils depending upon the different crude types, production systems, geographic location etc. It is also known that in a number of comparative LCA analyses between petrochemical products and bio-based alternatives there can be rather small differences (e.g. 10 – 20%) in the GHG emissions or other environmental impacts. The large potential range in emissions profile per unit of crude oil and the sometimes-small margin of difference between crude-oil based products and alternatives suggests that the specific route of crude production (and processing) will be an important factor in decision-making and policy centred on environmental criteria. The research in this thesis was conducted to examine the site-specific air emission data, with emphasis on VOCs, for crude oil production and how this could affect the results of LCAs of petrochemical products in comparison with the use of generic LCA database data to characterize the environmental profiles of such products. Company specific air emission data was collected from an upstream crude oil & gas company in Kuwait. The data collected was company available modelled data and new field measurements collected via the use of a mobile laboratory. This emission data was converted to specific substance emission values via Gaussian plume modelling and relating it to crude oil flows in the upstream facilities. Thereby new, specific LCI datasets for the air emissions of Kuwaiti crude oil were developed and deployed in LCAs to assess their effects on the environmental profiles of such crude oil and its end products. These LCAs demonstrated considerable heterogeneity in aspects of the environmental profile of the crude oils and example downstream end products driven by the specific LCI datasets for the various production systems examined.

The potential for generating renewable electricity from palm oil mill residues (POMR) has received policy support from the Malaysian Government for almost two decades. However, uptake of the technology is still relatively low. A significant issue dominating the discussion for many years is how to translate the renewable electricity generation potential from POMR into actual implementation. The research seeks to understand the opportunities and barriers for the use of POMR for a Renewable Electricity System (POMR-RES) in Peninsular Malaysia by assessing the technical, techno-economic and environmental feasibility of generating renewable electricity from palm oil mill residues focusing mainly on empty fruit bunches (EFB) and biogas. A combination of mathematical analysis and simulation using Aspen PlusTM software was employed to assess the technical feasibility of the system. Techno-economic analysis was combined with Life Cycle Assessment (LCA) to integrate the environmental impact perspective into the POMR-RES evaluation. The results show that EFB has better technical and techno-economic performance than the biogas. Furthermore, the on-site POMR-RES with an installed capacity of 5.70 MW or greater is technically feasible, economically viable and environmentally favourable. The electricity generated from a POMR-RES of this scale is sufficient to meet a mill's operational electricity demand, the parasitic load of the POMR-RES and provide surplus electricity to the national grid. An economically feasible size POMR-RES are expected to provide: 1. a 20% return on investment (ROI) with five to seven-year payback period (PP). 2. a positive net present value (NPV) with break-even point (BEP) of five to seven-year. The electricity generated in POMR-RES emits 95% less GHG emissions compared with current Malaysian electricity grid average when the emission from LUC is excluded from the electricity generation process. Thirty-five mills in Peninsular Malaysia were identified as having sufficient EFB supply to operate at or above this economically feasible size with the total accumulated generation capacity of 200 MW. This accumulated capacity would account for 25% of the 2020 target for palm oil biomass under National Renewable Energy Policy and Action Plan. This research provides a positive case for generating local, renewable electricity from EFB that can be used as evidence and practical recommendations for various actors such as prospective investors, analysts, stakeholders, mill owners and policymakers and government agencies such as the Sustainable Energy Development Authority Malaysia (SEDA) for efficient and sustainable utilization of POMR. This study also makes a positive contribution towards achieving the national renewable energy target for additional renewable power supplies and as a contribution towards improved global sustainability.

Global consumption for confectionery products are growing and is exerting enormous pressures on confectionery supply chains across the world to efficiently utilise natural resources towards becoming environmentally sustainable. However, there are a disparate range of studies investigating the environmental impacts of confectionery products, and more importantly how to improve environmental sustainability performance. In this thesis, the aim was to improve knowledge of opportunities for reducing environmental impact in confectionery manufacturing – from factory to supply chain – by developing methodological tools based on heat integration and Life Cycle Assessment (LCA). A range of novel methodologies were developed to advance heat integration and LCA knowledge, including (1) a heat integration framework combining direct and indirect heat exchange from zonal to multiple zones, possibly incorporating heat pump technology to enhance low grade heat recovery; (2) methodologies for systematically improving Life Cycle Inventory (LCI) data based on the role of multinational companies and for conducting effective LCA for confectionery products; and (3) a methodology to assess and quantify the environmental life cycle impacts of multi-product food factories. These methodologies have been applied at a multi-product confectionery factory, which has revealed significant findings: (1) combining direct and indirect heat integration from zonal to multiple zones can reduce factory energy by 4.04–6.05%, (2) heat pump technology can reduce factory energy by up to 29.2% but imposes design complexity and long economic paybacks up to 6.62 years, (3) fine bakery ware products on average was found to have the highest aggregated environmental life cycle impacts (higher than chocolate products by 7.1%, milk-based products by 18%, and sugar by 51.9%), and (4) combined improvement strategies of 50% energy reduction with 100% renewable energy, zero food waste to landfill (inc. 50% food waste reduction), and raw material changes to lower impacts can potentially reduce: Global Warming Potential by 65.82%, water depletion by 43.02%, abiotic depletion potential by 20.66%, land use by 17.45% and ecosystem quality by 7.24%. Overall, this research has culminated in several contributions to knowledge which substantially increases understanding of how to improve the environmental sustainability of confectionery manufacturing across the product, factory and supply chain level. The research will serve as a guide for future improvements, research and policies of confectionery manufacturers, supply chain actors, policy makers, and research institutes.

It is well accepted that the technical, financial and environmental performance of a chemical process is largely determined during design. Therefore, the development of tools that integrate environmental considerations would enable the design of more environmentally friendly processes at a lower cost. This research investigates how Life Cycle Assessment (LCA) can be applied at any stage in the design process to produce useful information for design, not just after the plant is operating, which is the norm for LCA. The tools have been applied to the development of a novel process (the RT7000): thermal cracking of mixed plastic waste to produce several hydrocarbon products with the potential to displace crude oil, naphtha, or refinery wax or be used as a fuel. To allow LCA to guide the design process, a toolkit methodology was developed including comparisons of design changes, hotspot analysis, identification of key impact categories, environmental break-even analysis, and decision analysis using ternary diagrams. The results of applying these tools justified continuing with the development by confirming that the novel process is likely to be a better environmental option than landfill or incineration. At the later stages of design, advanced tools such as process simulations become attractive and allow a more accurate estimation of material and energy flows. A simulation of the RT7000 in Aspen Plus® was developed that provided data for a wide range of feed compositions. The RT7000 continued to have lower environmental impact to incineration offering a saving equivalent to 969-1305 kgCO2/tonne plastic processed. It was also ascertained that variation in feed composition does influence environmental performance, but not enough to affect the outcomes of decision making. The general approaches used in this work to assess the RT7000 should be applicable to the development of any new process. Benefits and insights similar to those obtained in the case study can realistically be expected when these methodologies are applied to any new processes. Therefore the results have been published in the Journal of Cleaner Production (Gear et al., 2018).

Energy based on non-renewable resources such as gas, oil, coal and nuclear fission, even with their serious problems of pollution, contributes to 86% of the global energy consumption. Oil will remain the dominant transport fuel: about 87% of transport fuel in 2030 will still be petroleum-based. Discoveries of conventional sources of light easy-to-access crude oil are becoming less common and current oil production levels are struggling to match demand, it is necessary to develop new non-conventional sources of oil in order to supplement conventional oil supply, whose demand is increasing continuously. A possible clue to solve this situation could be to take advantage of the extensive reserves of heavy crude oils existing in different places around the world, which could be an excellent source of more valuable hydrocarbons. In this context, some facilities called upgraders are used to process theses heavy crude oils to both increase the hydrogen-carbon ratio and improve their quality, reducing their density and decreasing their viscosity, sulphur, nitrogen and metals. The main objective in this work is to study the heavy crude oil upgrading processes in order to identify new operation schemes which explore different opportunities of integration between the upgraders and other processes or new schemes for upgraders that can sustain on its own through the production of a wide range of products. Each design alternative has been modelled with state-of-the-art commercial software packages. The crude oil dilution process was evaluated using naphtha and a light crude oil as diluents. Sensitivity analyses were done with the purpose of selecting the type and flow rate of diluent. Once the best diluent was selected, the integration of an upgrader to a refinery was studied. Heavy ends from both the upgrader and the refinery were taken as feedstocks to an integrated gasification combined cycle (IGCC). The best operation schemes for IGCC, in order to achieve the requirements of power and hydrogen for the upgrader and the refinery was determined. Different schemes for heavy crude oil processing to produce transportation fuel instead of syncrude were proposed, too. Finally, economic evaluation of all the schemes was performed to find the best solution for heavy crude oils. The best results for the dilution process of heavy crude oils were obtained when naphtha was used as diluent. The configuration proposed for the upgrader allows producing a synthetic crude oil with 35.5 °API. The integration of the upgrader to a refinery allows the treatment of the heavy streams of the refinery and transforms them into products of higher qualities. The integration of the IGCC to the upgrader and the refinery permits a complete elimination of the heavy residues produced in these units and produces hydrogen and power to be used in the site or to export. Economic evaluation shows that all the proposed processing schemes studied are economically attractive. The proposed processing schemes chosen include the integration between upgrader refinery and IGCC unit with CCS.

Utilisation of biomass resources and CO2 abatement systems in currently exploited fossil resource based energy systems are the key strategies in resolving energy sustainability issue and combating against global climate change. These strategies are affected by high energy penalty and high investment. Therefore, it is imperative to assess the viability of these energy systems and further identify niche problem areas associated with energy efficiency and economic performance improvement. The current research work has two parts. The first part presents techno-economic investigation of thermochemical conversion of biomass into the production of fuels (Fischer-Tropsch liquid or methanol) and electricity. The work encompasses centralised bio-oil integrated gasification plant, assuming that the bio-oil is supplied from distributed pyrolysis plant. Bio-oil is a high energy density liquid derived from biomass fast pyrolysis process, providing advantages in transport and storage. Various bio-oil based integrated gasification system configurations were studied. The configurations were varied based on oxygen supply units, once-through and full conversion configurations and a range of capacities from small to large scale. The second part of this thesis considers integration of various CO2 abatement strategies in coal integrated gasification systems. The CO2 abatement strategies under consideration include CO2 capture and storage, CO2 capture and reuse as well as CO2 reuse from flue gas. These facilities are integrated into cogeneration or polygeneration systems. The cogeneration concept refers to the production of combined heat and power while polygeneration concept is an integrated system converting one or more feedstocks into three or more products. Polygeneration is advocated in this work attributed to its high efficiency and lower emission. Furthermore, it can generate a balanced set of products consisting of fuels, electricity and chemicals. It is regarded as a promising way of addressing the future rapidly growing energy demands. A holistic approach using systematic analytical frameworks comprising simulation modelling, process integration and economic analysis has been developed and adopted consistently throughout the study for the techno-economic performance evaluation of decarbonised fossil and bio-oil based systems. Important design methodology, sensitivity analysis of process parameters and process system modifications are proposed. These are to enhance the efficiency as well as lower the economic and environmental impacts of polygeneration systems. A shortcut methodology has also been developed as a decision-making tool for effective selection from a portfolio of CO2 abatement options and integrated systems. Critical and comprehensive analyses of all the systems under considerations are presented. These embrace the impact of carbon tax, product price evaluation and recommendations for sustainability of low carbon energy systems.