Water-Energy Nexus Cascade Analysis (WENCA) for simultaneous water-energy system optimisation

This paper presents a new numerical method called the Water-Energy Nexus Cascade Analysis (WENCA), developed based on the principal of Pinch Analysis. Water and energy are both valuable resources that are majorly used in industrial processes. Both water and energy are interdependent where increasing water demand will increase the energy demand and vice versa. In this paper, WENCA is introduced to simultaneously optimise both water and energy system that is interdependent. The methodology applies Cascade Analysis to individually optimise both system. As both systems are interdependent, altering one of the system will result in a change to the other system. An iterative method is then introduced to converge the analysis to obtain the optimal result for both systems. A case study comprising of both electricity and water demand of 6,875 kWh and 3,000 m3 from a residential area with 1,000 unit of houses is applied in this work. The electricity demand is met using fuel cell where hydrogen is produced through coal gasification (which utilised water as it raw material), a water treatment plant (WTP) is also introduced for water treatment to fulfil the water demands. The optimal result reveals that the WTP capacity is 3,200.73 m3, its corresponding water storage tank capacity is 175 m3, hydrogen power plant is 9 MW and its corresponding energy storage capacity is 4.13 MW

Multiple-resources targeting using water-energy nexus cascade analysis and mathematical modelling

Energy and water are two valuable resources that are mainly utilized in all sectors, from residential consumption to industrial processes. As conservation of resources are crucial, optimisation of energy and water system is becoming important. Pinch technology is an outstanding methodology and well known for its simplicity among the various targeting techniques. Previous targeting problems which are solved using the pinch analysis only focused on optimisation of single resource which may lead to under-sizing of system, as systems may rely on one another to operate. The water-energy nexus cascade analysis is introduced with the purpose to concurrently target both water and energy system. A case study involving a residential community comprising of 50,000 household unit with daily electricity demand of 343,750 kWh and water demand of 150,000 m3 is adapted. An integrated gasifier fuel cell is used to meet electricity demand while a water treatment plant is used to meet clean water demand. The results show the highest difference of 9.1% of the system capacities compared to methodology using single resource targeting method such as electric system cascade analysis. Sensitivity analysis is also performed to study the significance of capacity differences if higher water or energy conversion rate is imposed. Nevertheless, water-energy nexus cascade analysis, similar with other pinch and cascade analysis, it lacks the capability to consider other variables such as cost in its analysis. As such, a mathematical model is developed to provide a more holistic approach to the targeting problem. It‘s revealed that using the mathematical modelling, the capacity of the system is larger. The resulting cost of the system is MYR 516.65 million. Apart from identifying the optimal capacity of the system, the study concluded that the higher the interdependency of resources, the differences becomes more significant. Therefore, when analysing system that shows an inter-dependent nature, it is important to consider both resources and target them simultaneously to prevent the system from being under-designed

Carbon Emission Pinch Analysis: an application to the transportation sector in Iskandar Malaysia for 2025

The energy sector has grown significantly over the years, causing an increase in carbon emission that has led to serious global warming problems. Consequently, electric vehicles (EVs) have become a favourable solution in the transportation sector due to their green technology attributes. This paper aims to apply the Carbon Emission Pinch Analysis (CEPA) method to the transportation sector in Iskandar Malaysia. The modified CEPA method is applied by constructing a composite curve for transportation modes and the total carbon emission was plotted in order to study the minimum electricity requirement that needs to be generated to implement the use of EVs. Road and rail transportation were considered in the transport composite curve based on the current policies available and to achieve the new carbon emission target by the year 2025. The alternatives available to reduce carbon emission in Iskandar Malaysia include increasing public transport modal share; fuel switching from petrol and diesel to natural gas and biofuels; and increasing transport efficiency via plug-in hybrid and EVs. Four scenarios were established and evaluated based on economic and environmental aspects. As a result, Scenario 4 which considered all policies available (transport management, fuel switching and fuel efficiency) have showed the most promising fuel mix for future transportation demands. An estimated total amount of 0.25 TJ of electricity is needed for EV implementation with a total estimated cost of RM 1.3 billion. The total carbon emission for this scenario is 1101.96 kt-CO2. This research can benefit the Government, town planners, or policy makers, for preliminary energy planning

Circular economy (CE): A framework towards sustainable low carbon development in Pengerang, Johor, Malaysia

Under the Malaysia’s National Key Economic Area (NKEA), Pengerang is set to become the largest regional petroleum refinery and trading hub in South East Asia and will be the focus centre in Asia and globally. This paper relates the basic theory of CE with Pengerang’s background, which is in the construction phase towards becoming the centre of integrated petrochemical refinery industry in Johor, Malaysia. CE in the petrochemical industry in Pengerang is briefly exposed in terms of overall constitutional framework, industrial management, energy cycle usage, and wastewater and sludge treatment. This paper outlines the reviews of current movements for Circular Economy (CE) based on the work of literature gathered in 2000 till 2017, its definitions, current best practices, and policy framework towards its implementation especially in highly industrialised petrochemical refinery industries in Europe and China. These mechanisms of CE are then synthesised and implementation framework for CE in Pengerang is produced. Despite this early investigation and literature exposure of CE in Pengerang, there is a need for further specific research to be conducted extensively, to acquire more understanding especially in the context of potential implementations, stakeholders’ involvement and awareness towards low carbon development in Pengerang, Johor, Malaysia via CE implementation

Palm Oil Mill Effluent (POME) biogas techno-economic analysis for utilisation as bio compressed natural gas

The production of palm oil will continue to rise with increasing demand of fats and oils. The increase of palm oil production will result in high production of palm oil mill effluent (POME). POME is polluting due to its high chemical oxygen demand (COD) and biological oxygen demand (BOD). High COD and BOD of POME has the advantage to produce large amount of biogas through anaerobic digestion (AD). As upgraded biogas has equal composition to natural gas, it can be potentially used as compressed natural gas (CNG) or also known as bio-CNG. Bio-CNG at its current state is too expensive for implementation where subsidies are required to enable the technology, especially for countries where energy price is low such as in Malaysia. This paper studies on the economic potential of the bio-processing technology which consists of an anaerobic digester, purification unit, and compression up to 20 MPa as the biogas will be utilised as CNG. The parameter that is considered in the economic analysis includes the cost of the AD, purification unit, compression of biogas (based on the outlet pressure of the purification unit up to 20 MPa), transportation cost of bio-CNG, and lastly the profit obtained from the sales of bio-CNG. It is revealed that the system that utilises membrane separation technology has the lowest payback period and hence is most economical