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Decentralized energy generation (DEG) system which characterizes local power generation and utilization are recently getting more attention in energy system planning and implementation because it produces cleaner energy from renewable resources and is capable to avoid significant energy losses during the power transfer from the centralized power plants. These DEGs are however scattered in locations and have intermittent power supply, making it difficult to self-sustain. In this study, a novel integrated energy system consisting of multiple DEGs connected to the existing CEG is proposed. New aspects that are included in the model include the distribution and transmission losses as well as impact of operating load on the heat rate of power plants. Energy storage system were also modelled to operate within the DEG and CEG network. Through a case study demonstration, the capacities of the integrated system were optimized using superstructure-based mixed integer non-linear programming (MINLP) mathematical modelling. The system was also optimized based on economic and energy efficiency to study the effects and trade-off between the two parameters. The results revealed that the optimal system can be obtained with levelized cost of electricity of MYR 0.44/kWh. The result also revealed that biomass and wind energy favours industrial users. Image 1 • Decentralized energy generation (DEG) system prioritizing intermittent sources. • Scheduling of the DEG and CEG is modelled separately considering changes in heat rate. • Combination of wind and biomass-based electricity for industrial use is recommended. • A single powered solar PV is recommended for residential users. • The model suggests to build a larger natural gas power plant with energy storage. [ABSTRACT FROM AUTHOR]

Abstract Heavy fossil fuels consumption has raised concerns over the energy security and climate change while hydrogen is regarded as the fuel of future to decarbonize global energy use. Hydrogen is commonly used as feedstocks in chemical industries and has a wide range of energy applications such as vehicle fuel, boiler fuel, and energy storage. However, the development of hydrogen energy in Malaysia is sluggish despite the predefined targets in hydrogen roadmap. This paper aims to study the future directions of hydrogen economy in Malaysia considering a variety of hydrogen applications. The potential approaches for hydrogen production, storage, distribution and application in Malaysia have been reviewed and the challenges of hydrogen economy are discussed. A conceptual framework for the accomplishment of hydrogen economy has been proposed where renewable hydrogen could penetrate Malaysia market in three phases. In the first phase, the market should aim to utilize the hydrogen as feedstock for chemical industries. Once the hydrogen production side is matured in the second phase, hydrogen should be used as fuel in internal combustion engines or burners. In the final phase hydrogen should be used as fuel for automobiles (using fuel cell), fuel-cell combined heat and power (CHP) and as energy storage. Highlights • Biomass and solar pathways for hydrogen production could be feasible in Malaysia. • Hydrogen can be used as transportation fuel, heating fuel and energy storage. • Hydrogen economy in Malaysia faces technical, economic and social challenges. • Renewable hydrogen could be commercialized in 3 phases via the proposed framework. [ABSTRACT FROM AUTHOR]

The difference in electricity pricing based on the time of power use has led to load shifting from peak to off-peak hours in hybrid power systems (HPS). Apart from optimising electricity cost, shifting of the load may also change the capacity of storage in the system. Power Pinch Analysis has been recently applied to guide load shifting aiming to minimise the cost of electricity, considering the peak and off-peak electricity pricing. The HPS was assumed to be ideal with 100% efficiency, which is not achievable in actual operational condition. This work extends the study by scrutinising the effects of peak-off-peak load shifting on the capacity of storage in HPS. The effects of energy losses due to the inefficiency during power conversion, transfer and storage in the HPS are considered in developing shifting heuristics to ensure optimal storage size is achieved. Implementation of the proposed load shifting strategy on a case study demonstrates that a reduction of up to 30% in the storage size can be achieved, which led to a minimum storage cost. The distribution of peak hours' demand to off-peak hours also successfully provide significant savings in the electricity bill. [ABSTRACT FROM AUTHOR]

The development of renewable energy is of paramount importance towards the energy security and environment integrity of Malaysia. The Malaysia government has been implementing various policies that could facilitate the advancement of renewable energy technology and increase its contribution to the national energy mix to reduce the country dependency on fossil fuels. On the other hand, due to rapid urbanization and population growth, there is also increasing concern over the high production rate of organic waste. Among the renewable energy available, biogas is of great interest due to its ability to treat organic waste and generate power addressing both concerns simultaneously. This paper aims to review some of the important policies on renewable energy followed by the emphasis on solid waste management policies towards effective implementation of biogas generation from municipal solid waste. The biogas network is divided into three phases on a life cycle basis, namely MSW as feedstock, biogas production and biogas utilization. Under each phase, several important stages were identified. Analysis was performed to identify the role of currently implemented policies as well as the lacking support and challenges. It was envisioned that with proper SWM policies, in terms of waste collection, waste segregation and allocation of resources, which can be further complemented with more financial initiatives and technical support under the RE policies, the biogas development in Malaysia can progress more efficiently. Several supportive actions needed were derived from the analysis and presented in three figures, representing each of the phase, which could constitute a solid biogas framework. [ABSTRACT FROM AUTHOR]

Improper waste management happened in most of the developing country where inadequate disposal of waste in landfill is commonly practiced. Apart from disposal, MSW can turn into valuable product through recycling, energy recovery, and biological recovery action as suggested in the hierarchy of waste management. This study presents a method known as Waste Management Pinch Analysis (WAMPA) to examine the implication of a dual-objective – landfill and GHG emission reduction target in sustainable waste management. WAMPA is capable to identify the capacity of each waste processing strategy through graphical representation. A general methodology of WAMPA is presented through a demonstration of a SWM case followed by a detailed representation of WAMPA for five waste types. Application of the WAMPA is then applied on a case study for sustainable waste management planning from year 2015 to 2035. Three waste management strategies are incorporated into the case study – landfill, Waste-to-Energy (WtE), and reduce, reuse, and recycle (3R). The results show a 13.5% of total GHG emission reduction and 54.6% of total reduction of landfill are achieved. The major contributor of GHG emission which are from food waste (landfill emission) and plastic (WtE emission) is reduced. [ABSTRACT FROM AUTHOR]

Valorisation of organic waste can lead to cleaner production in the energy sector. One factor affecting the decision for organic waste valorisation to value-added products through biological processes is the carbon-to-nitrogen (C/N) ratio. All biological processes have preferential C/N ratios for optimum performance, while organic waste comes with a wide range of C/N ratios. The mismatch of the C/N ratio between the supply stream (organic waste) and the demand stream (biological process) can lead to suboptimal process performance and affect resource allocation. In this study, a new graphical C/N ratio Pinch Analysis approach was proposed by plotting cumulative carbon mass flowrate versus the cumulative nitrogen mass flowrate as x- and y-axes for the supply and demand sides. A series of graphical Supply Composite Curve (SCC) shifting, namely SCC right-shifting, SCC end-shifting, SCC detaching, and SCC down-shifting, were developed explicitly tackling different supply stream conditions in the hypothetical case studies while satisfying the demand streams with the aid of external supply. The external supply was determined by filling the gaps formed after the SCC was shifted to the right of the Demand Composite Curve (DCC). Specific heuristics were established to assess the range of C/N ratio for the external supply that is eligible and preferred to satisfy the demand streams. Stepwise procedures for mass flowrate allocation to mix the supply and match the demand were introduced. In this study, the demands for Case Study 1 were satisfied by 59.15% OWLA with 40.83% ES 3. For Case Study 2, the demands were satisfied by 76.19% OWLA with 23.81% ES 1. For Case Study 3, the demands were satisfied by 91.54% OWLA with 8.46% ES 1. The integration of the C/N ratio element in the Pinch-based Analysis of SCC shifting and exploring new optimisation scope can act as an advising tool for any individual, party, or organisation to optimally valorise the organic waste found within a local region. • Valorise organic waste via Pinch Analysis focusing on the carbon-to-nitrogen ratio. • Introduction of heuristics to determine the eligible and preferred external supply. • Stepwise procedures for mass flowrate allocation from supply to demand. • Majority of the demand mass flowrates satisfied by organic waste locally available. • Developed methodology applicable to any bioprocesses by valorising organic wastes. [ABSTRACT FROM AUTHOR]

Energy storage (ES) is an important device to ensure operation stability and efficiency of a renewable energy based distributed energy generation (DEG) system. As such, many researchers have modelled the operation (scheduling) of energy storage in a DEG system, where it is mostly portrayed to operate on a daily cycle. In this paper, an analysis of the operation mode of energy storage is presented. Two modes of operation are defined, daily mode (DM) (ES operates in daily cycles) and weekly mode (WM) (ES operates in weekly cycles) which are modelled accordingly. This paper then attempts to analyse and compare between both modes in term of operation and cost. The analysis is performed through a mixed integer linear programming (MILP) model programmed via the General Algebraic Modelling System (GAMS). In general, with high capital cost of ES, it is advisable to program the ES to operate in a DM. The reason to this conclusion is mainly due to three factors, intermittency of renewable resources, varying weather conditions, and discharge rate of ES(s). [ABSTRACT FROM AUTHOR]

The utilisation of municipal solid waste (MSW) for energy production has been implemented globally for many decades. Malaysia, however, is still highly dependent on landfills for MSW management. Because of the concern for greenhouse gases (GHG) emission and the scarcity of land, Malaysia has an urgent need for a better waste management strategy. This study aims to evaluate the energy, economic and environmental (3E) impact of waste-to-energy (WTE) for municipal solid waste management. An existing landfill in Malaysia is selected as the case study for consideration to adopt the advanced WTE technologies including the landfill gas recovery system (LFGRS), incineration, anaerobic digestion (AD), and gasification. The study presented an interactive comparison of different WTE scenarios and followed by further discussion on waste incineration and AD as the two potential WTE options in Malaysia. The 3E assessment reveals incineration as the superior technology choice when the production of electricity and heat were considered; however, AD is found to be more favourable under the consideration of electricity production only. [ABSTRACT FROM AUTHOR]

Highlights: [•] Advancement of ESCA method for designing and sizing of solar PV system [•] Influenced of weather variability and system configuration on cascade analysis. [•] Optimize the size of mains units in the system. [ABSTRACT FROM AUTHOR]

Despite the ability of renewables to decarbonize energy use, their intermittent nature causes inconsistent energy generation, thus energy storage is required to tackle the supply-demand mismatch. While the use of hybrid battery-hydrogen energy storage for microgrids has been extensively studied, there is a lack of study on the integration of electricity and hydrogen supply systems. In other words, the concurrent targeting of hydrogen and electrical loads in a microgrid with hybrid battery-hydrogen storage is lacking. This study presents an optimization framework for the design and operation of a standalone microgrid with electrical and hydrogen loads. Two energy management strategies have been proposed and the optimization model is solved using particle swarm optimization algorithm. The proposed methodology was demonstrated through a case study and the levelized cost of energy ranges from 0.4551 USD/kWh to 0.4572 USD/kWh for the base case scenario. The optimal microgrid design in base case scenario is found to have a high value of potential energy waste possibility, indicating that the solar panel is oversized to reduce energy storage requirement. Sensitivity analysis results showed that a significant cost reduction can be achieved when only 95% of loads are targeted. [Display omitted] • Optimization of microgrid using particle swarm optimization method. • Design of microgrid considering fluctuations in energy profiles. • Integrated hydrogen and electricity supply systems. • Evaluation of the cost-effectiveness of solar tracking system. • Results proposed the most appropriate energy management strategy for microgrid. [ABSTRACT FROM AUTHOR]

Renewable energy is the key to decarbonize energy use despite the growing global energy demand. However, energy storage is required to tackle the supply-demand mismatch caused by the intermittent nature of renewable energy sources. As each type of energy storage has a distinct discharge duration, a hybrid energy storage system can be more cost-effective than a single energy storage system. While various process integration tools have been employed for the optimization of microgrid with hybrid energy storage, a graph theoretic algorithm known as P-graph allows the identification of optimal and near-optimal solutions for practical decision making. P-graph involves modelling by graphs and the embedded accelerated branch-and-bound algorithm enables efficient determination of optimal solution. This study proposes a multi-period P-graph optimization framework for the optimization of photovoltaic-based microgrid with battery-hydrogen energy storage and the proposed approach is demonstrated through two case studies. Results showed that the optimal cost of microgrid with hybrid battery-hydrogen storage is 704,990 USD/y, a carbon price of 1000 USD/t and above is required to make it more economical than conventional electricity use. Replacing the hydrogen storage system with grid support reduces the total cost and required carbon price to 262,334 USD /y and 300 USD /y respectively. [Display omitted] • A multi-period P-graph optimization framework for renewable energy system. • Targeting of battery and hydrogen storage in microgrid. • The proposed methodology is demonstrated using two case studies. • Economic feasibility of microgrid and suitable rates of carbon pricing are studied. • The method is useful for the targeting of microgrid with intermittent energy source. [ABSTRACT FROM AUTHOR]

Abstract: Effective policies and incentive on renewable energy (RE) is critical to promote low carbon economy and society in the future. RE was first introduced in the country''s energy mix through the Fifth-Fuel Policy which was formulated under the Eighth Malaysia Plan (2001–2005) to reduce dependency on fossil fuel and to address the rising global concern on climate change. This paper addresses the RE progress and achievement over the past 10 years, and discusses the key policies for RE programmes, funding, schemes, and incentives that has been introduced by the government of Malaysia to develop and promote the utilisation of RE. The recent RE mechanisms under the Tenth Malaysia Plan (2011–2015) will also be highlighted. [Copyright &y& Elsevier]

The exploitation of renewable energy sources is crucial in promoting energy transition from fossil-based to renewable-based, but their intermittent nature causes the mismatch of energy supply and demand. This can be resolved using an energy storage to store the excess energy from renewables and release it when the energy supply is in deficit. Hydrogen has a good potential for energy storage as it can tackle the spatial differences in renewable energy supply, but its storage in compressed gas or cryogenic liquid form incurs high investment cost. Liquid organic hydrogen carrier offers a cheaper and more convenient way of storing hydrogen as compared to conventional means. This paper proposes a cascade analysis approach for the targeting and scheduling of a self-sufficient standalone energy system that is fully supported by renewables and with liquid organic hydrogen carrier as energy storage. The fraction of hydrogen and electricity consumed for the system self-requirement is first determined before cascade analysis is performed to identify the optimal capacity of the energy system. Results indicated that 255,020 m2 of solar panel is required for a region with 45.1 MWh daily electricity demand. If the system energy requirement is neglected, most equipment would be undersized by about 40%. • Liquid organic hydrogen carrier as energy storage for renewable energy system. • Enhanced cascade analysis for self-sufficient energy system. • Reuse of energy produced to cover the heat and electricity demand of the system. • Targeting of distributed energy generation system for optimal sizing. • Scheduling of energy system operation on hourly basis. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) conversion to energy through waste-to-energy technologies (WtE) is promising in offering sustainable and environmentally friendly answers to MSW disposal problems. This paper proposes a quantitative safety, health and environmental (SHE) index for WtE selection. This technique compares WtE technologies according to SHE hazards posed by the chemicals produced. Scores representing the level of hazards expected is assigned to SHE parameters through the implementation of the logistic function. These scores are then added to produce a single score representing the technologies called the Safety, Health and Environmental Total Score (SHETS). Technologies with a lower score are more preferable than a higher score. This technique was applied to a case study of landfill gas recovery system, incineration, gasification, and anaerobic digestion. Incineration is evaluated as the least preferred technology with SHETS value of 54.74 mainly due to the existence of sulfur dioxide which has high atmospheric toxicity and acidification potential while gasification is the most preferred waste-to-energy technology with SHETS value of 50.82. The developed index provides insight on SHE hazards of the chemicals produced allowing the adoption of preventive measures for the development of WtE technology that is efficient in energy production, safer, healthier and environmentally friendlier. Image 10369 • A quantitative safety, health and environmental index for waste to energy technology selection. • Utilizes logistic function for scores construction of each parameters. • Incorporates three safety parameters, three health parameters and five environmental parameters in the assessment. • The technique proposed focus on the impact of chemicals in term of safety, health and environmental (SHE) domains. [ABSTRACT FROM AUTHOR]

The hybrid power system (HPS) that integrates diesel/biodiesel plant with renewable energy (RE) technologies has become increasingly popular to alleviate greenhouse gases emissions issue of the sole diesel/biodiesel power system. Integrated diesel-RE power system offers cleaner power supply while minimising cost of diesel fuel and diesel system maintenance. The use of Power Pinch Analysis (PoPA) method for the integration of diesel plants and RE systems into HPS with the objective to minimise fuel requirement and operational time of diesel generator has been presented. This work aims to achieve the same objective via probability theory utilisation, to simplify the PoPA procedure involving the matching of various routes for power flows. The extended technique called the Probability-Power Pinch Analysis (P-PoPA) can give accurate results as those established from the PoPA method within a shorter analysis time because it replaces the tedious manual matching step with correction factors. All probable routes of power from RE and diesel generators to demands are considered in computing the correction factors, in order to target the minimum diesel power in the integrated system. The result of a Case Study demonstrates that 19% saving in diesel fuel consumption can be realised if the present diesel station is supported with renewable solar power in an HPS. The result of the P-PoPA method is accurate with a very minor deviation to that from the conventional PoPA technique. [ABSTRACT FROM AUTHOR]

Energy is widely used in industry for heating and cooling, with natural gas (NG) being the largest primary energy source in Malaysia, closely followed by coal. Renewable energy, such as biogas upgrading to biomethane, could cut the use of fossil fuels by supplementing NG usage due to their similar physicochemical and thermochemical characteristics. Biogas production plants in Malaysia are more commonly seen in waste-to-energy scenarios, with the technology anaerobic digestion, and their deployment is supported via feed-in tariffs (FiT) for power generation. Other potential applications such as the conversion of biogas into biomethane, injection into the natural gas grid or transportation through a virtual pipeline may still need further technical development. This paper presents spatial techno economic optimisation modelling using BeWhere to determine decentralised biomethane production plants using feedstock from multiple sources of biogas, including palm oil mill effluent (POME), food waste, cattle manure and chicken manure. This model considered potential configurations and sizes of the biomethane plants, the transportation of biomethane using a virtual pipeline (at 250 psig) and demand in one of the states in Malaysia, namely Johor. It was found that two to four biomethane plants with capacities ranging between 125 and 700 m3/h were located in densely populated areas or heavier industrial consumers when the carbon tax was implemented at 167.71 EUR/tCO 2 (800 MYR/tCO2). Sensitivity analysis suggested that biomethane production increases with the increasing country renewable energy share target to beyond 2080 MW. It is recommended that specific policy regulations and Feed-in Tariff (FiT) mechanisms are used to expand the biomethane market share in the country. • A spatially explicit optimisation model is extended for biomethane injection. • Highly populated and heavy industry areas are selected for plant construction. • Carbon price and subsidy rationalisation are crucial to promote biomethane injection. [ABSTRACT FROM AUTHOR]

Total Site (TS) analysis for incorporating short-term or daily energy variation has been introduced in the previous studies as an extension of the Time Slice Model for the Heat Integration of batch processes. However, the energy supply and demand fluctuation could also be affected by changing customer demands due to seasonal climate variations, economic downturn, maintenance, plant turn-around, plant operability issues and raw material availability. This paper extended the cascade energy targeting methodology for TSHI incorporating long- and short-term heat energy supply and demand variation problem. The methodology aims to estimate the energy requirements of the TS system considering seasonal energy storage system as a feasibility study for energy efficiency project. A newly extended algebraic tool, known as Seasonal Total Site Heat Storage Cascade (Seasonal TS-HSC), is introduced in the methodology for modelling the energy flow between process units and storage facilities. The general tool could be used for different storage systems. This proposed tool includes the estimation of energy losses through self-discharge, charge and discharge process based on the energy storage system performance. The methodology is illustrated by a case study, which integrates batch processes, community buildings and space heating system. Implementation of the developed methodology on the case study resulted in 93.4% (low-pressure steam - LPS) and 38.2% (hot water - HW) heating requirement reduction via seasonal energy storage system application at two utility levels. The result shows the energy requirement reduction, which contributes to profitability margin improvement, greenhouse gas emission reduction potential and regional sustainability enhancement, through seasonal energy storage system in the industrial energy system. [ABSTRACT FROM AUTHOR]

The airflow distribution in an operating room plays a vital role in preventing surgical site infection by diluting and removing particles released by medical staff, lowering particle settlement on a patient. This study aims to computationally examine the efficiency of a ceiling-mounted air curtain in reducing particle distribution in a surgical zone. A computational fluid dynamic (CFD) software simulated an operating room's airflow and particle movements using the corresponding Re-Normalisation Group (RNG) k-ε model and a Lagrangian model. The baseline case and case 1 simulations were equipped with air supply diffusers, while cases 2 to 5 utilised combined air supply diffusers and air curtains. The results revealed that an air curtain fails to reduce particle settlement on a patient. In fact, the use of air curtain in cases 2, 3, 4, and 5 led to an unwanted 3.3-, 4.3-, 3.0-, and 6.7-fold increased particle settlement, respectively. On a positive note, the study found that increasing the area of the air supply diffuser from 4.32 to 7.74 m2 favourably reduced the number of particles by 33.3%. [ABSTRACT FROM AUTHOR]

Biomethane, a renewable gas (RG), is gaining popularity globally since the advocacy for greenhouse gas (GHG) emission reductions. Biomethane includes upgraded biogas and upgraded landfill gas. Upgraded biogas is generated and upgraded from biomass, for example, energy crops or agricultural waste through anaerobic digestion, while upgraded landfill gas is collected and upgraded directly from gas released from a landfill site. In Malaysia, biogas and landfill gas are usually used on site. The potential for transporting upgraded biogas for off-site utilisation through pipeline injection is yet to be explored. This paper presents economic models, spatial analysis and scenario analysis to identify an appropriate biogas supply chain to different demand: industrial area, commercial area and residential area at different pressures: 20 psig, 4.3 psig and 0.43 psig through injection into the natural gas grid. The trade-off between the compression pressure and the distance of transportation is assessed and the results reveal that injection of biogas into the natural gas gate for industrial usage at 20 psig is the best option, with associated costs of 2.07 × 10 9 MYR/y. The cost is higher than supplying the demand with natural gas, which has an annual cost of MYR 985.87 M. Therefore, incentives for sales of biogas and turning the environmental liability of methane gas emitted from the landfill into an economic opportunity is essential so that the biogas can be sold at a competitive price as natural gas. The methodology can be applied at regional and country level to support policy makers to define and implement a strategy for future landfill gas to be injected into the natural gas grid in order achieve the country's renewable energy target of 30% in 2025. [ABSTRACT FROM AUTHOR]

Development of Power Pinch Analysis (PoPA) for the design and optimisation of Hybrid Power Systems (HPS) is steadily progressing. Even though PoPA has been developed for a wide range of applications in HPS design and analysis, the economic aspect still needs more attention. Screening of various renewable energy (RE) technologies in HPS is crucial as different technologies may have different cost and efficiencies, and affect the overall system economics. This work presents a novel framework for the design of a cost-effective HPS by incorporating PoPA with a cost-screening tool known as the Systematic Hierarchical Approach for Resilient Process Screening (SHARPS). SHARPS, which was originally developed to screen various process changes options in water networks is adapted to perform economic analysis and RE technology screening in power networks. Two strategies namely substitution and intensification have been proposed, in order to customise a cost-effective HPS. The presented framework provides a handy and effective measure to visualise the trade-off between the performance and cost of various potential RE technologies for HPS. Application of the framework on a case study demonstrates that the HPS design has been successfully customised with the RE technology scheme and capacity acceptable to the owner, while meeting its targeted payback period of 10 y. [ABSTRACT FROM AUTHOR]

Electric buses are getting more interest to be implemented in the public transport sector by different countries as a carbon mitigation strategy. However, there are a few issues with electric buses such as limited driving range and long recharging time compared to the conventional diesel bus. Due to its limited energy storage, estimation of the energy consumption for the electric buses becomes a crucial research area to prevent sufficient energy for electric buses during the service. The long recharging time of the electric buses requires a vehicle and a charging scheduling to ensure fulfilling the passenger demand without compromising the energy demand. The paper will review the state-of-the-art model for the energy forecasting model of the electric buses and electric bus charging scheduling models. The paper then compares the parameter in the energy forecasting model, the optimization objective, the charger technology, the charging pattern, and the constraint in the electric bus scheduling model. The purpose is to provide a well-structured comprehensive review on these energy forecasting and electric bus charging scheduling for engineers, researchers, investors, policy makers, bus depot companies, and other interested parties. • A comprehensive review of electric bus forecasting and scheduling model is provided. • Electric bus energy forecasting models and their parameters are reviewed. • Electric bus charging scheduling models and their model constraints are reviewed. • Variables and objectives in charging scheduling optimization model are reviewed. • Overall suggestions for forecasting and scheduling model are recommended. [ABSTRACT FROM AUTHOR]

With the rapid population growth and industrial development in the fast developing countries, there is a significant increase in the production of waste. For instance, the municipal solid waste in Malaysia is expected to exceed 9 Mt/y by 2020 based on the current production rate of 1 kg − 1 person −1 . Approximately 90% of the waste is channelled into the landfill that can release a significant amount of greenhouse gases, mainly the methane gas and nitrous oxide gases, due to the anaerobic decomposition of organic matter. Composting is a cleaner alternative to landfilling for managing organic waste. Its main advantage lies in its capability to recycle nutrients through compost utilisation. The life cycle assessment has been widely used as a mean of comparison for impact assessment, such as global warming potential, among different waste management technologies. The common inventories accounted for composting include transportation, operational machineries, fugitive emissions during maturation and curing as well as the end production utilisation. There is inconsistency in the methodology adopted to assess its environmental impact. This study discusses on the variations of life cycle assessment that contributed to the different global warming potential of composting. It also discusses on the mitigation strategies to reduce the global warming potential for composting. The highlight of the study is to examine the variation in the inventory analysis for composting, and its underlying mechanism and the critical inventory for a more representative assessment. The second part of the paper reviews the mitigation strategies for reducing the greenhouse gas emissions, i.e. the use of the bulking agent, aeration system, chemical additives and use of the cover material. This study found that the direct greenhouse gas emissions during composting contribute more significantly to the global warming potential than other direct emissions. The use of bulking agent is desirable to reduce the global warming potential. This study concludes that the assessment of the global warming potential for composting is dependent on the system boundary and the defined functional unit. The environmental impact should be assessed based on the operational mode and the input feedstock to generate a basis with minimised discrepancies among studies. Continuous effort is needed to quantify the long-term benefits of composting on environment, health and soil to further assess its impact as a cleaner process. [ABSTRACT FROM AUTHOR]

In a typical operation of palm oil mill, oil palm residues and palm oil mill effluent (POME) would be produced. While the oil palm residues have been well harnessed as biomass fuel, regional planning of efficient POME utilisation via biogas recovery and upgrading, coupled with possible biogas compressed natural gas (bioCNG) transshipment among the palm oil mill cluster, deserves more research and development. In this study, the objective is to design a modelling tool for optimising the oil palm biomass and POME utilisation pathway as well as bioCNG distribution network for a palm oil mill cluster with maximum simultaneous economic satisfaction level. Fuzzy optimisation approach was applied for this proposed multiple-objective modelling problem. Two case studies were simulated by the developed mathematical tool to examine the economic benefit of POME utilisation pathway in multiple-site palm oil processing complex (POPC) design. Moreover, the impact of feed-in-tariff (FIT) quota variation on POPC and bioCNG transshipment pathway designs was examined. From the simulation, it was found that POME utilisation pathway incorporation had increased the overall annual worth by MYR 15,049,096 per year due to additional revenues from bioCNG and biogas-derived electricity sales as well as utility saving. [ABSTRACT FROM AUTHOR]

An overview of numerical and mathematical modelling-based distributed generation (DG) system optimisation techniques is presented in this review paper. The objective is to compare different aspects of these two broad classes of DG optimisation techniques, explore their applications, and identify potential research directions from reviewed studies. Introductory descriptions of general electrical power system and DG system are first provided, followed by reviews on renewable resource assessment, load demand analysis, model formulation, and optimisation techniques. In renewable resource assessment model review, uncertain solar and wind energy resources are emphasised whereas applications of forecasting models have been highlighted based on their prediction horizons, computational power requirement, and training data intensity. For DG optimisation framework, (solar, wind and tidal) power generator, energy storage and energy balance models are discussed; in optimisation technique section, both numerical and mathematical modelling optimisation methods are reviewed, analysed and criticised with recommendations for their improvements. In overall, this review provides preliminary guidelines, research gaps and recommendations for developing a better and more user-friendly DG energy planning optimisation tool. [ABSTRACT FROM AUTHOR]

Anaerobic digestion of renewable feedstocks has been known as a prospective technology for the production of clean energy in the form of biogas. Biogas is a sustainable energy carrier which is mainly composed of methane (60%) and carbon dioxide (35–40%). Among the raw substances, organic matters obtained from farm animal waste are pivotal sources for biogas production. In recent years, the number of animal husbandry has drastically grown in Malaysia. Accordingly, a large amount of animal waste including manure, blood and rumen content are produced which provide a tremendous source of biogas generation. This paper presents biogas potential from the organic waste obtained from the farm animals and slaughterhouses in Malaysia. The findings of this study indicated that biogas potential of 4589.49 million m 3 year − 1 could be produced from animal waste in Malaysia in 2012 which could provide an electricity generation of 8.27×10 9 kWh year −1 . [ABSTRACT FROM AUTHOR]

Clean electricity is generated by the anaerobic digestion of biomass waste. The environmental impacts of various biomass waste feedstocks vary, while co-digestion has been reported to improve anaerobic digestion performance. A consequential life-cycle assessment (LCA) and techno-economic analysis (TEA) are carried out for cow manure waste management for a cow farm. Three scenarios are considered in this study: (S1) mono-digestion of cow manure, (S2) co-digestion of cow manure and maize silage, and (S3) co-digestion of cow manure with cow feed waste, sewage sludge, and returned dairy products. The LCA aims to quantify the environmental impact of each MWh of electricity generated, assuming the plant is located in Malaysia, using OpenLCA software. The TEA economic parameters are quantified and compared between the three scenarios. Net present value (NPV), Internal Return Rate (IRR), and Return of Investment (ROI) are examined. Among the three scenarios, S2 with maize cultivation has a higher environmental impact due to its higher energy requirements. With the integration of closed digestate storage and renewable energy-powered electricity, S3 has the best environmental performance in global warming, eutrophication and acidification. S3 is found to be most economically viable, with MYR 1.28 million NPV, 14% IRR, and 15% ROI, and a Payback Period of 6.56 years with an OPEX of MYR 3491.82/MWh. [ABSTRACT FROM AUTHOR]

An operating room is a healthcare facility used to perform surgical operations on a patient. The OR demands high-air cleanliness and sterile conditions to reduce the risk of patients contracting surgical site infections. However, previous research stated that noticeable particle concentrations were identified near the surgery area. This scenario could elevate the tendency of particles to settle on the patient’s wound and subsequently cause SSIs. Therefore, this study examines the effectiveness of innovative localised exhaust and air curtains in reducing the number of particles settling on the patient. An OR model was constructed using computer-aided design (CAD), while the airflow and particle simulation were performed using computational fluid dynamics (CFD). The reliability of the present work was verified and validated using established data before the case study. A Re-Normalisation Group (RNG) k–ε model based on the Eulerian approach was used to simulate the airflow. In contrast, a discrete phase model (DPM) based on the Lagrangian approach was used to simulate the airborne particle dispersion. Results showed that the activation of the localised exhaust located on the two sides of the operating table could reduce the total particle settlement on the patient by 26% when compared to the baseline ventilation system. The installation of an additional air curtain showed the best performance in terms of reducing the particle settlement, followed by the installation of both an additional air curtain and a localised exhaust outlet. The particle concentration settled on a patient showed a positive relationship with the body surface area, which is expressed by equation y = 0.1088x + 0.2528 with a coefficient of determination, R2 value = 0.8764. This study suggests that adopting localised exhaust and air curtain systems in ORs could greatly improve infection control, enhance patient safety and elevate healthcare quality and outcomes. [ABSTRACT FROM AUTHOR]

Airborne Microplastics (MPs), an emerging environmental issue, have gained recent attention due to their newfound presence in indoor environments. Utilizing the Web of Science database for literature collection, the paper presents a comprehensive review of airborne MPs including emission sources, assessment methods, exposure risks, and mitigation strategies. This review delves into the diverse sources and mechanisms influencing indoor airborne MP pollution, underscoring the complex interplay between human activities, ventilation systems, and the characteristics of indoor environments. Major sources include the abrasion of synthetic textiles and the deterioration of flooring materials, with factors like carpeting, airflow, and ventilation significantly impacting MP levels. Human activities, such as increased movement in indoor spaces and the intensive use of plastic-based personal protective equipment (PPE) post-pandemic, notably elevate indoor MP concentrations. The potential health impacts of airborne MPs are increasingly concerning, with evidence suggesting their role in respiratory, immune, and nervous system diseases. Despite this, there is a scarcity of information on MPs in diverse indoor environments and the inhalation risks associated with the frequent use of PPE. This review also stresses the importance of developing effective strategies to reduce MP emissions, such as employing HEPA-filtered vacuums, minimizing the use of synthetic textiles, and enhancing indoor ventilation. Several future research directions were proposed, including detailed temporal analyses of indoor MP levels, interactions of MP with other atmospheric pollutants, the transport dynamics of inhalable MPs (≤10 μm), and comprehensive human exposure risk assessments. [Display omitted] [ABSTRACT FROM AUTHOR]

• High air change rate caused swirling airflow and particle recirculation. • Ceiling-mounted air supply diffuser and low-level exhaust promotes particle removal. • RNG k-ε turbulence is the most suitable model for simulating airflow in an elevator. An elevator is a machine that vertically transports people between different levels of a building. It is a typical confined space for contracting airborne diseases, such as coronavirus disease 2019 (COVID-19). The purpose of this study is to examine the dispersion of sneeze particles on the infection risk among passengers in a public elevator. A computational fluid dynamics (CFD) model representing an elevator was constructed. A CFD model was verified and validated based on the onsite measurement data. Renormalization Group (RNG) k-ε turbulence model developed based on the Eulerian tracking approach was used to simulate the airflow, while the discrete phase model (DPM) developed based on the Lagrangian tracking approach was used to simulate the particle dispersion during sneezing process. Simulation results show that particle concentration increased by 10 % and 2 % in case 2 (ceiling-mounted air supply diffuser and one low-level exhaust outlet) and case 3 (ceiling-mounted air supply diffuser and exhaust outlet), respectively. In contrast, case 4 shows that integration of the ceiling-mounted air supply diffuser with two-sided low-level exhaust outlet) minimized the particle adherence by 34 % on the manikin, from the time of 0 s – 5 s. Thus, ventilation strategy demonstrated in case 4 is sufficient to minimize particle dispersion and has a particle reduction rate of 0.006 kg/m3 ∙ s. Although case 1 (ceiling-mounted air supply diffuser and ceiling-mounted exhaust outlet) could prevent the particles trapped on the manikin from 0 s to 5 s, it does not perform well from the time of 5 s – 10 s. [ABSTRACT FROM AUTHOR]

Utilisation of palm oil mill effluent (POME) appears to be a promising source of bioenergy production specifically biogas. Biogas products have different spatial structure varying on the level of centrality and dispersion of palm oil mill (POM), significantly impacting the transportation and total cost of biogas production. Pinch analysis provides systematic solution to industrial energy planning. However, the current pinch analysis lacks the ability to simultaneously consider CO 2 emission target and to minimise cost for bioenergy supply chain. This study presents an integrated spatial and pinch analysis to determine the least cost energy mix to satisfy industrial energy demand and GHG emission target. The selection of cost-competitive energy substitution is evaluated based on supply cost factor constructed with spatial consideration, emission reduction to cost increase (ECI) ratio and emission reduction with cost decrease (ECD) values. To demonstrate the proposed framework, a case study to meet 120 MW of industrial energy demand in the state of Johor, Malaysia was presented. The results indicated that natural gas from grid extension and bio-compressed natural gas (BioCNG) with upgrading were required to achieve 30% GHG emission reduction. The total cost of energy mix was reduced significantly from 25.16 M USD/y to 17.56 M USD/y. • Cost and emission factor of energy supplies are considered simultaneously. • Natural gas and biogas based energy supplies contribute to optimum energy mix. • Optimised energy mix results to a total of 27.3% cost reduction. [ABSTRACT FROM AUTHOR]

Lately International Energy Agency (IEA) highlighted the vital role the biogas and anaerobic digester (AD) in the advent of circular economy. Organic residues or waste will be converted into high-value products, power, heating and fuel in the future of bio-economy. This study look specifically into the institutional and market factor, of a Feed-in Tariff (FiT) mechanism as a policy instrument to promote integration of biomethane into existing gas grid. In the circumstance where market is not in the favour of bioenergy/biogas, with fossil fuels are subsidised under national economic policy of the case study in Malaysia; this study found that under the current piped natural gas price, the proposed FiT, 34.02–141.79 MYR/GJ (7.13–29.73 EUR/GJ) is economically incompetent for biomethane to be injected into the grid without other policy and mandate support. However, natural gas price rationalisation may close the price gap, this is especially for biomethane derived from palm oil mill effluent (POME) and food waste at 4 MW size. Through Net Present Value (NPV) approach, among the four locally available feedstock assessed in this study: POME, food waste, chicken manures and cattle manures; POME and food waste show lower levelised cost due to minimal competing utilisation value in addition to their higher biogas conversion rate. POME prevails as a feedstock choice for its uniform composition and on-site production advantage. Discussion and recommendations based on the current policy scenarios in Malaysia are provided in the section following results and findings. • Four feedstocks are studied: palm oil mill effluent, food waste, chicken manure, cattle manure. • Proposed Feed-in Tariff ranges between 34.02 and 141.79 MYR/GJ (7.13–29.73 EUR/GJ). • Palm oil mill effluent prevails as a feedstock choice for its uniform composition and on-site production advantage. [ABSTRACT FROM AUTHOR]

Global depletion of fossil fuels, growing awareness on the effects of carbon emissions and greenhouse gases and, the need for renewable energy, has increased the attention towards biocoke research and active engagement with various research groups and industrial players. Biocoke production and utilisation is crucial as it contributes to the efficient management of agricultural residue and municipal solid waste. The technologies involved in the biocoke production and the viability of Malaysia's agricultural waste as a feedstock was described in this paper. In addition, the paper provided background information about the biocoke characteristics and the feedstocks that dictate quality. Comparisons of commercial coal coke and biocoke production technologies that may be applicable to Malaysia were also addressed. Moreover, the paper demonstrated the challenges towards Malaysia's biocoke commercialisation despite its viability from biomass feedstocks characteristics, availability, and evidence of calorific value estimations. [ABSTRACT FROM AUTHOR]

Rapid development and population increment over the past decades have led metropolises in the tropical regions such as Kuala Lumpur (KL) city to the issue of surging local energy demand, especially cooling energy demand. Most commercial and office buildings install conventional air-conditioning (AC) at individual premises for space conditioning. AC constitutes an average high of 58% of the total energy consumption in a building. In the meantime, the amount of municipal solid waste produced is also proliferating. KL as a city with compact population and limited land mass for waste disposal, the implementation of a large-scale centralised district cooling system (DCS) fuelled with biogas energy seems to be more sustainable. This study aims to assess the performance of various possible cooling system schemes in providing cooling service to office buildings in tropical urban, including the existing AC system and the newly proposed DCS technology integrated with biogas energy. Three parameters which are energy consumption, greenhouse gas emission and economic viability are analysed on a yearly basis. With a total cooling load of 4008 kW to be supplied to five similar buildings in KL, seven case scenarios involving different cooling schemes of AC and DCS are studied and compared. The result determines that biogas-fuelled cooling systems are as attractive as the grid-electrified systems. Currently, AC unit operating with on-site biogas-generated electricity is the most desirable cooling scheme for KL city, with an annual worth of MYR -1.004 M/y and greenhouse gas avoidance of 41.1 kt CO 2 eq./y. DCS may not be a preferred option yet due to its high investment and operation costs. A sensitivity analysis conducted shows that there is a need to increase the current electricity tariff (up to at least MYR 1.49–1.56/kWh) in order to make DCS more economically attractive as the conventional AC units. [ABSTRACT FROM AUTHOR]

Transboundary haze has been a critical environmental concern in the region of Southeast Asia in the recent decades. The smoke occurred by land clearing through burning activities for agricultural cultivation and urban development is a significant contributors to haze issue which has affected countries within the region and beyond. Instead of ‘slashing and burning’ the biomass residues, there is the possibility of utilising the biomass residue produced either by land-clearing or on plantations to become higher value bio-products,with monetary returns to the plantations and farmers. Due to the diffuse nature of biomass which leads to high transportation costs, effective spatial planning is required for cost-effectiveness and sustainable biomass supply. This study focuses on mitigation of transboundary haze by moving away from the conventional activities of biomass ‘slash and burn’ through its conversion to energy. A spatial optimal biomass allocation networks has been developed to address the issue of transportation distance of biomass to the centralised bioenergy facility by taking into account the geographical locations of the biomass, biomass availability, distances, and transportation cost. Five optimal centralised biomass facilities were identified in Peninsular Malaysia. The results indicated that the cost of electricity generated from oil palm trunk (OPT) and oil palm frond (OPF) was USD 0.13/kWh which is comparable with current Feed-in-Tariff (FiT). The result suggests that the conversion of biomass–to-energy could create economic benefits and ultimately reduce open burning practices, and prevent the transboundary haze issue in Malaysia and other ASEAN countries. [ABSTRACT FROM AUTHOR]

Anaerobic digestion is one of the major biological-based technologies for converting organic waste to energy. The end-product of the process is the production of biogas that can be harvested as renewable energy and a nutrient-rich digestate that can be transformed as biofertiliser. Food waste varies seasonally and geographically, leading to a variation of biogas potential among different studies. There is still a lack of study on the relationship among the variation of food waste characteristic, its effect on the operational parameters and their inhibition value and its effect on the efficiency of the methods for improving biogas production. This paper reviews the anaerobic digestion of food waste in three sections: the characteristic of food waste reported in the literature, mono-digestion of food waste and co-digestion of food waste with other feedstocks. This review aims to relate the characteristics of food waste to biogas potential and to propose process improvement for enhanced biogas production. Food waste showed variation in terms of bromatological analysis, where the carbohydrates was reported to be around 11.8–74%, protein was 13.8–18.1% and lipid was 3.78–33.72%. The biogas yield for mono-digestion of food waste was 0.27–0.642 m 3 CH 4 /kg VS and for the co-digestion of food waste with other substrates was 0.272–0.859 m 3 CH 4 /kg VS. It has been concluded that the variation in the characteristic of food waste, in terms of physical and biochemical properties, can affect the efficiency of the applied treatment for process improvement, including nutrient balance, mechanical treatment, thermal treatment and two-stage configuration. Co-digestion remains an effective method for biogas production from food waste. Thermal treatment can significantly increase biogas production but excessive treatment can reduce the biodegradability of food waste. Mechanical treatment is more effective in treating waste rich in cellulosic material. [ABSTRACT FROM AUTHOR]

Abstract: Rapid population growth and urbanisation have generated large amount of municipal solid waste (MSW) in many cities. Up to 40–60% of Malaysia’s MSW is reported to be food waste where such waste is highly putrescible and can cause bad odour and public health issue if its disposal is delayed. In this study, the implementation of community composting in a village within Iskandar Malaysia is presented as a case study to showcase effective MSW management and mitigation of GHG emission. The selected village, Felda Taib Andak (FTA), is located within a palm oil plantation and a crude palm oil processing mill. This project showcases a community-composting prototype to compost food and oil palm wastes into high quality compost. The objective of this article is to highlight the economic and environment impacts of a community-based composting project to the key stakeholders in the community, including residents, oil palm plantation owners and palm oil mill operators by comparing three different scenarios, through a life cycle approach, in terms of the greenhouse gas emission and cost benefit analysis. First scenario is the baseline case, where all the domestic waste is sent to landfill site. In the second scenario, a small-scale centralised composting project was implemented. In the third scenario, the data obtained from Scenario 2 was used to do a projection on the GHG emission and costing analysis for a pilot-scale centralised composting plant. The study showed a reduction potential of 71.64% on GHG emission through the diversion of food waste from landfill, compost utilisation and significant revenue from the compost sale in Scenario 3. This thus provided better insight into the feasibility and desirability in implementing a pilot-scale centralised composting plant for a sub-urban community in Malaysia to achieve a low carbon and self-sustainable society, in terms of environment and economic aspects. [ABSTRACT FROM AUTHOR]

• Higher walking velocity induced significant secondary airflow. • Walking velocity of 1.0 m/s reduced the number of particles settled on patient. • Higher walking velocity potentially reduces the infection risk on a burn patient. An isolation ward requires a highly controlled and contamination-free environment since the settling of bacteria-carrying particles (shed by medical staff) on patients' wounds could cause infections. The present study examines the effect of medical staff's walking movement on airflow distribution and particle dispersion. Three different walking speeds of 0.25 m/s, 0.5 m/s, and 1.0 m/s were assigned to the medical staff. An RNG k-ɛ model based on the Reynolds-Averaged Navier-Stokes (RANS) equation was adopted to predict the airflow, while a Lagrangian tracking approach was selected to track particle dispersion. The reliability of the selected airflow turbulent model and particle tracking approach was validated using published data. The present study showed that the low-pressure region behind the moving medical staff's body has induced wake. The higher walking speed of 1.00 m/s produced a significant secondary airflow of 1.12 m/s, while 0.25 m/s and 0.5 m/s generated lower secondary airflow of 0.41 m/s and 0.53 m/s, respectively. The number of particles settled on the patient at 0.25 m/s, 0.50 m/s, and 1.00 m/s were 31, 18 and 5, respectively. Present finding indicated that a higher walking speed reduces the number of particles settled on the burn patient, therefore potentially reducing the associated nosocomial infection risk. [ABSTRACT FROM AUTHOR]

Hydrogen is seen as the future energy that will help decarbonise the emissions of global energy use. Hydrogen-related technologies have recently attracted considerable attention due to their relatively low emissions and high energy yield. Even then, little attention was given to hydrogen's use in energy distribution networks. A renewable-based multi-energy system (RMES) considers power, cooling, heating, and hydrogen energy as utility systems for integrated urban and industrial areas to achieve urban-industrial symbiosis. This paper formulates the RMES as a multi-period mixed-integer nonlinear programming (MINLP) model to optimise the RMES, which minimises the financial implications and environmental impacts. Renewable solar energy is provided to the system using the photovoltaic solar system for electrical generation and the solar thermal collector for heat generation. Thermal, battery and hydrogen energy storages are integrated into the RMES to mitigate the energy supply and demand fluctuations and intermittency. A comparative analysis is conducted to individually identify the performance of different energy storage systems for economic and environmental objective functions. The comparison findings indicate that ESS performs better with 45% usage increases under objective environmental functions. The multi-objective optimisation using the ϵ-constraint method obtains the Pareto optimal solutions to the proposed multi-objective problem, which the 4th solution (ATC: 782,500 USD/y; ACE: 2,777.03 kg CO 2 -eq/y) appears to be the most viable. The solution maintains a high-profit level without sacrificing many opportunities for carbon emissions reduction while satisfying both objective functions simultaneously to a degree of satisfaction of 0.75. Overall, the proposed RMES is proven economical and environmentally friendly for implementation; however, the model is needed to optimise the system based on the specific situation. This study provides the optimisation model for energy recovery and technology optimisation in the multi-energy system for urban-industrial symbiosis, which minimises carbon emission and energy cost. This could lead the energy sector to achieve the Sustainable Development Goals, considering the economically and environmentally viable. • Renewable-based multi-energy system for urban-industrial symbiosis. • Heating, electricity, cooling and hydrogen energy demands are considered. • Multi-period optimisation based on economic and environmental factors. • Thermochemical, battery and hydrogen storages are compared. • Multi-objective optimisation for obtaining the non-dominating Pareto optimal. [ABSTRACT FROM AUTHOR]

Biofuel is an attractive vehicular fuel option for the transportation sector. Diverse biofuel blends can be produced from biomass. Complexity arises when optimum biofuel blends need to be designed to comply with fuel regulation standards as well as generate less emission. This paper discusses an integrated computational and experimental technique to design economically viable and environmentally friendly tailor-made biofuel blends from palm biomass that is abundant in Malaysia. An experimental based trial-and-error method is time consuming and uses up resources. Computational approaches adopt a systematic blend formulation methodology that assists focused experimental work. The biofuel design problem has been formulated as a Non-Linear Program to satisfy specified target properties such as density, kinematic viscosity, cetane number, gross calorific value, distillation temperature, and sulphur content. Target properties predicted through mixture property models were experimentally validated according to ASTM standard test methods. Five optimum tailor-made biofuel blend formulations were generated based on cost, gross calorific value and emission limitations. The result indicates that biofuel blends with butyl levulinate could increase the price of biofuel up to 80% from the retail price of B5 diesel. However, cleaner biofuel with less cost and highest calorific value can be achieved for biofuel blends that contain B5 diesel, butanol and ethanol. The application of this model yields about 26% CO 2 emission reduction and about 22% less sulphur content as well as comply with the EN590 fuel regulation standard. [ABSTRACT FROM AUTHOR]

Biogas decentralised energy system is an important technology in developed countries nowadays as one of the energy efficient and eco-friendly techniques for production of bioenergy besides giving significant impact towards reduction of disposed waste volume and greenhouse gas (GHG). The aim of this article is to present a new numerical method, i.e., Gas System Cascading Analysis (GASCA), based on Time Based Pinch Analysis (TBPA) principle. GASCA is capable of targeting the biogas supply-demand chain, as well as optimal capacities of anaerobic digestion (AD) and biogas storage systems for a known total demand profile, with the consideration of energy conversion efficiency for different biogas qualities, charging and discharging efficiencies and losses. In the illustrative case study, the optimal capacity of AD was 4629.52 MJ/h, with initial energy content and maximum energy capacity at biogas storage of 8737.19 MJ/h and 16,988.61 MJ/h. The simulation study also revealed that application of GASCA-optimised biogas energy system could potentially reduce carbon emission by up to 138 t CO 2 eq /d. Moreover, a sensitivity analysis was conducted to examine the impacts of demand variations on biogas system design and regional feedstock selection. [ABSTRACT FROM AUTHOR]

Power Pinch Analysis is an established method to target the design parameter of a Hybrid Power System. This study aims to develop an extended tool known as Probability-Power Pinch Analysis (P-PoPA) using probability theory to simplify the process of Power Pinch Analysis in considering efficiency losses. The method targets for a Hybrid Power System with various current type from generation to demand, generation to storage, or storage to demand. The procedure of the method is illustrated using an electricity-deficit scenario where both AC–DC generation and AC–DC demand are present. The new methodology which adapts the same concept as the Stand-Alone Hybrid System Power Pinch Analysis utilizes data extracted from an ideal (considering no efficiency losses) graphical Power Pinch Analysis and Power Cascade Table and multiplying the extracted data with a probability factor to obtain an estimated target (considering efficiency losses) for the power system. In this study, three design parameters are determined for a system with 208 kW h AC source and 50 kW h DC source and 170 kW h AC demand and 98 kW h DC demand. The external energy that is needed for the system is identified as 38.93 kW h and the energy capacity of energy storage is 42.20 kW h and power capacity of energy storage is 8.79 kW. The result is then compared with the existing cascade analysis, Power Cascade Table and Storage Cascade Table. The determined sizing values have a close estimation to that from cascading analysis (considering efficiency losses), with a maximum percentage difference of 2.3%. [ABSTRACT FROM AUTHOR]

The application of on-grid hybrid power system (HPS) has been effective for harnessing renewable energy resources and ensuring environmental sustainability. A number of algebraic and mathematical modeling approaches have been introduced for the optimisation of on-grid HPS. While algebraic power pinch analysis (PoPA) tools have been developed to enable the selection of cost-effective energy storage technology, the available mathematical modeling approaches have yet to consider the economics and storage system selection in the design of an optimal on-grid HPS. This work presents a mixed-integer linear programming (MILP) for the optimal design of an on-grid HPS with the minimum net present value (NPV) of the overall electricity production cost and the selection of the optimum energy storage technology. Two case studies are presented in this work. In the former, the differences between the developed MILP model and previous methods are highlighted, with sensitivity analysis to investigate the impact of electricity tariff on the on-grid HPS. In the second case study, the developed MILP model was applied to an Eco-Industrial Park (EIP) case study with energy storage technology selection. Lead-acid battery system was found to be the optimal choice due to its low investment requirement. [ABSTRACT FROM AUTHOR]

Global warming issue, which increasingly aggravates over time, necessitates the carbon capture and storage (CCS) technology for its efficient mitigation. Among the major CCS technologies, post-combustion capture is the most established and commonly employed. However, it poses several energy and environment-related problems. As such, research and development of the pre-combustion carbon capture has been conducted to overcome the drawbacks of this conventional approach, and incorporation of ionic liquid (IL) has been increasingly given attention. This paper intends to review the carbon dioxide separation technologies and those related to IL in pre-combustion capture, pre-combustion capture research progress, pilot plant and commercial facilities, as well as modelling approach with special focus on the computer-aided molecular design (CAMD). In the last aspect, emphasis is given to the IL-based UNIFAC model, and key research gaps are identified from the review as general guidelines for the future research work and development in this particular field. [ABSTRACT FROM AUTHOR]

Ineffective waste management that involves dumping of waste in landfills may degrade valuable land resources and emit methane gas (CH 4 ), a more potent greenhouse gas than carbon dioxide (CO 2 ). The incineration of waste also emits polluted chemicals such as dioxin and particle. Therefore, from a solid waste management perspective, both landfilling and incineration practices pose challenges to the development of a green and sustainable future. Waste-to-energy (WtE) has become a promising strategy catering to these issues because the utilisation of waste reduces the amount of landfilled waste (overcoming land resource issues) while increasing renewable energy production. The goal of this paper is to evaluate the energy and carbon reduction potential in Malaysia for various WtE strategies for municipal solid waste (MSW). The material properties of the MSW, its energy conversion potential and subsequent greenhouse gases (GHG) emissions are analysed based on the chemical compositions and biogenic carbon fractions of the waste. The GHG emission reduction potential is also calculated by considering fossil fuel displacement and CH 4 avoidance from landfilling. In this paper, five different scenarios are analysed with results indicating a integration of landfill gas (LFG) recovery systems and waste incinerator as the major and minor WtE strategies shows the highest economical benefit with optimal GHG mitigation and energy potential. Sensitivity analysis on the effect of moisture content of MSW towards energy potential and GHG emissions are performed. These evaluations of WtE strategies provides valuable insights for policy decision in MSW management practices with cost effective, energy benefit, environmental protection. [ABSTRACT FROM AUTHOR]

Abstract: Ineffective management of municipal solid waste (MSW) may cause degradation of valuable land resources and create long-term environmental and human health problems. A sustainable and efficient waste management strategy is needed to balance the need for development, the quality of human life and the environment. This study aims to synthesis a MSW processing network to produce energy and value-added products for achieving economic and environmental competitiveness. An optimisation model that integrates four major utilisation technologies was incorporated to facilitate a cost-effective processing network. The model is able to predict the best mix of waste treatment technologies, forecast the production of by-product from waste treatment process, estimate the facility capacity, forecast the greenhouse gas (GHG) emission of the system, and eventually generate an optimal cost-effective solution for municipal solid waste management (MSWM). Four scenarios for MSWM were considered to analyse the economic impact of different waste utilisation alternatives: i) the business as usual (BAU) scenario as a baseline study, ii) the waste-to-energy (WTE) scenario, iii) the waste-to-recycling (WTR) scenario, and iv) the mixed technology (MIXTECH) scenario. The MIXTECH scenario was able to provide the best mix of waste utilisation technologies. The optimal waste allocation in terms of percentage involved landfill gas recovery system (LFGRS) (14%), mass burn incineration (3%), material recycling facilities (MRF) (56%), and composting (27%). The optimal scenario would be able to achieve the renewable energy (RE) target, achieve the recycling target and promote composting as the waste reduction alternative for the region being studied. Sensitivity analyses were conducted for the optimal or MIXTECH scenario to examine the effect of the RE target and GHG emission reduction target with respect to the system cost and waste allocation to each technology. The proposed mixed integer linear programming (MILP) model was applied for Iskandar Malaysia (IM) as a case study. [Copyright &y& Elsevier]

The concept of industrial symbiosis that promotes energy/material exchanges among different industrial enterprises has received growing attention. Industrial symbiosis synergistically engages traditionally separate entities to gain competitive advantages and efficiency in the consumption and utilisation of resources, utilities and wastes. Process integration is a powerful tool to optimise processes and identify scope for industrial symbiosis. Numerous studies have investigated the application of process integration in regard to the management of material resources. Previous works to guide systematic industrial symbiosis planning has only focused on low-carbon emission sites. There is a need to develop a systematic guideline for industrial site planners to use for the systematic planning of integrated industrial sites that also considers other resources such as waste and water. This research presents a framework for the systematic planning of an integrated industrial site using process integration tools. The framework comprises eight main stages and includes six process integration tools to systematically guide the planning and design of industrial sites to minimise energy, water, waste and emissions. A 95.58% reduction of waste disposal through landfilling, a 33.4% reduction in carbon emissions from waste disposal, a 45.70% reduction in steam, a 27.48% cooling water savings, 100% power reduction, a 49.10% reduction in CO 2 emissions, 100% fresh CO 2 savings, and a 100% freshwater savings for water headers 1 and 2 are obtained from the case study applying the framework proposed. The framework application will provide insights on how all the utilities and materials streams in the involving industries can be comprehensively integrated, hence reducing the need for fresh resources and promoting sustainability. [Display omitted] • Integrated industrial site planning framework for synergising multiple process integration tools. • An integrated guideline for industrial site planners to conserve resources. • Guideline to target minimum resources utilisation in industrial site. • Efficient industrial site planning towards a circular economy. • The physical arrangement of industries for maximisation of the materials exchange. [ABSTRACT FROM AUTHOR]

Sustainability and Industrial Ecology (IE) are the main drivers of industrial symbiosis (InSys) and eco-industrial parks (EIPs). InSys, therefore, extends the idea of industrial ecology (IE) to the industrial sector by adopting a resource-efficient approach where one firm uses the unused or residual resources (materials, energy, water, assets, logistics, and expertise) of another firm. The aim is to enhance a sustainable and cleaner production in an environmentally friendly way, one in which generation of wastes and emission of greenhouse gases (including CO 2) is minimized. Although previous literatures have investigated existing InSys tools, the utilization of the process integration (PI) tools for InSys design and planning has mostly operated in isolation of each other and thus concentrated on individual resources which makes the it hard for InSys designers to select the best tools. Furthermore, there is a dearth in research on comprehensive and integrated resource optimization, which considers the integration of all resources (such as energy, water, power, carbon and wastes) within InSys simultaneously. Therefore, this study investigated and surveyed available literatures in order to identify and develop a more comprehensive description of InSys tools, through the analysis of related methodologies and applications by integration of various resources optimization tools together for the design and establishment of EIPs. The tools are inclusive of both insight-based Pinch Analysis and mathematical optimization models approaches. The review also conducted a bibliometric analysis of some keywords using Scopus over a span of twenty-two years (1998–2019). Through the insights and understanding gained from the review, designers will be more equipped to make a more informed choice of working tools to utilize. Finally, suggestions were offered on some tools that will enhance the integration of eco-industrial parks to minimize fresh water/wastewater, minimize fuel use and reduce GHGs emissions and the minimization of cooling, heating and power requirements in Total Sites. The review of integrated resource optimization tools is then followed by identifying future research directions and development. Image 1 • Process integration (PI), mathematical optimization (MO) methods and other models are reviewed in this work. • A bibliometric analysis of industrial symbiosis (InSys) concept and tools are conducted. • A better understanding of InSys tools for the design and establishment of eco-industrial parks (EIPs) is enhanced. • A valuable insight for researchers, planners and other stakeholders. [ABSTRACT FROM AUTHOR]