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

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

Palm oil mill effluent (POME) biogas off-site utilization Malaysia specification and legislation

Biogas generated from anaerobic digestion of palm oil mill effluent (POME) is one of the highly potential renewable energy (RE) sources in Malaysia that can be used for a variety of application including electricity generation, heating and as fuel for vehicular transportation. While POME biogas can contribute a substantial amount of energy to the nation, POME biogas plants are usually located in rural area thus hindering wide application of the biogas. Supply of biogas is commonly higher than its demand in rural area and excess biogas is flared. It is proposed that excess biogas should be transported to location with higher energy demand. Biogas can be transported via truck (in a form of compressed biogas) or via existing natural gas pipeline. As biogas often consist only of approximately 60 % bio-methane, it is crucial to upgrade the biogas by scrubbing and compressing to make biogas transportation and distribution economical. The specification of biogas is different for different storage system as well as for different distribution by truck and pipeline. Considering the factor of safety and quality, the specification of biogas need to comply with the Malaysian Standards and Regulations which function to monitor the welfare and quality of biogas. This paper emphasised the options of POME biogas for off-site utilization that follow the requirement of Malaysian Standards and Regulations

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

Mathematical optimisation of biogas production and utilisation

Palm oil mill effluent (POME) is a source of biogas generation that can be a substitute for fossil fuel. High content of biological oxygen demand (BOD) and chemical oxygen demand (COD) of POME has the advantage to produce large amount of biogas through anaerobic digestion. The purpose of this research is to develop a mathematical model to determine the optimal process pathway of biogas, covering from the purification technology to mode of transportation and utilization. A hypothetical case study is conducted to run and test the model, in which different target location with different utilization mode was chosen. The model chose membrane separation of biogas, pipeline transportation to the targeted site, and electricity generation as the optimal pathway for biogas processing and utilization. Sensitivity analysis is performed to determine the impact of product price on the biogas process pathway selection. The sensitivity analysis revealed that the price of Bio-CNG has an impact on the model. Sensitivity analysis suggested the Bio-CNG sales price should be at least 10.4 USD/GJ to be economically feasible