Jeng Shiun Lim

A multi-period model for optimal planning of an integrated, resource-efficient rice mill

Abstract Rice is one of the worlds most important staple foods. Previous studies have focused on the yield improvement for an individual rice mill. There is a need to develop a framework to address the multitude of variables influencing the design of a rice mill complex, which include fluctuating thermal and electrical energy demands, diverse energy supply options, fluctuating product demands, resource availability and product degradation. The objective of this study is to develop a framework for the optimal design and planning of the product portfolio and processing route of an integrated, resource-efficient (IRE) rice mill complex. The objective function is to maximise the profitability of the rice mill by using the developed multi-period mathematical model. Sensitivity analysis was performed on the case study to evaluate the impact of fluctuating product demands, product prices and electricity cost on the production throughput, process configuration and profitability of the IRE rice mill complex.

Optimal operation of a distributed energy generation system for a sustainable palm oil-based eco-community.

Abstract The palm oil industry potentially can be environmentally sustainable through utilizing the vast availability of biomass residues from palm oil mills as renewable energy sources. This work addresses the optimal operation of a combined bioenergy and solar PV distributed energy generation system to meet the electricity and heat demands of an eco-community comprising a palm oil mill and its surrounding residential community. A multiperiod mixed-integer linear programming planning and scheduling model is formulated on an hourly basis that optimally selects the power generation mix from among available biomass, biogas, and solar energy resources with consideration for energy storage and load shifting. A multiscenario approach is employed that considers scenarios in the form of many possible weather conditions and various energy profiles under varying mill operation modes and residential electricity consumption. The proposed approach is demonstrated on a realistic case study for a palm oil mill in the Iskandar Malaysia economic development region. The computational results indicate that biomass-based resource is the preferred renewable energy to be implemented due to the high cost associated with solar PV. As well, load shifting and energy storage can be feasibly deployed for demand peak shaving particularly for solar PV systems.

Review of microalgae growth in palm oil mill effluent for lipid production

Wastewater treatment using microalgae is an eco-friendly process without secondary pollution. During the process, the wastewater produced is reused, which allows efficient nutrient recycling. This review provides constructive information to enable progress of competent technology for microalgae based productions in palm oil mill effluent (POME). The characteristics of POME that will be described in this paper would be a source of pollution in water if discharged directly. Since microalgae have great potential to be isolated and cultivated in POME, previous studies to improve POME based culture media are still limited. Microalgae are highly competent in diminishing CO2 emissions and reducing the organic components in POME. In conclusion, biological treatments by using microalgae discussed in this paper and the lipid production from microalgae biomass can be used as an alternative for energy production. The POME treatment with microalgae may meet the standards or limits before being discharged into the water body.

Integrated biomass and solar town concept for smart eco-village

Integrated Biomass and Solar Town Concept for Smart Eco-Village Haslenda Hashim*, Wai Shin Ho, Jeng Shiun Lim, Sandro Macchietto Process System Engineering Center (PROSPECT), Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia Centre for Process Systems Engineering , Imperial College London, Roderic Hill Building, South Kensington Campus, London, SW7 2AZ haslenda@cheme.utm.my

Towards low carbon society in Iskandar Malaysia: Implementation and feasibility of community organic waste composting

Rapid population growth and urbanisation have generated large amount of municipal solid waste (MSW) in many cities. Up to 40-60% of Malaysias 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.

Power Pinch Analysis supply side management: strategy on purchasing and selling of electricity

Pinch analysis concept has been recently stepped into the realm of design and optimisation of power systems. One well-established pinch analysis that has been used in power systems design and optimisation is called Power Pinch Analysis (PoPA). In PoPA, both graphical and numerical approaches have provided an insight on the systematic approach to target and design various power systems. By only visualising the minimum amount of outsource energy required by the power system, the graphical PoPA method as a whole does not show the purchasing of outsource energy based on the exact time intervals. Using graphical PoPA, the objective of this study is to determine a proper strategy to buy and sell outsource electricity to improve the overall performance of a hybrid power system comprising renewable power generators and energy storage system. The strategies are made based on three design parameters: energy-related capacity, power-related capacity of energy storage and maximum grid power rating between centralised grid and hybrid power system. While deciding on the best strategy and heuristics to be implemented, the effects on system operation and economy are indirectly analysed. It is experimented that the output can benefit electricity consumers or producers.

Superstructure-based synthesis and optimisation of an oil palm eco-industrial town: a case study in Iskandar Malaysia

Malaysia is one of the world’s top edible oil producers, having more than 5.23 million hectares of palm oil plantations and more than 400 palm oil mills. The oil palm industry produces millions of tonnes of biomass waste during harvesting and mill processing. This paper presents an oil palm eco-industrial town (EIT) that integrates a palm oil mill with nine downstream oil palm-based industries, as well as a community. The downstream industries produce various types of products such as crude palm oil, bio-fertiliser, bio-gas, bio-diesel, bio-pellet, medium-density fibreboard (MDF), and are also involved in the paper industry, and livestock production. Through the concept of industry symbiosis, the oil palm EIT promotes energy and material sharing among the industries and the community to reduce energy consumption, virgin material consumption, and waste generation. Therefore, this concept could provide economic and environmental benefits to upstream industries (utilisation of biomass), downstream industries (conversion of biomass to valuable products), and the community (job creation). In this work, a multi-objective linear programming model is formulated to maximise economic performance, while minimising waste generation in the oil palm EIT. The applicability of the model is demonstrated using a case study in Iskandar Malaysia (IM). The optimised model suggests that the most efficient way to utilise abundant oil palm biomass is via the production of crude palm oil, MDF, bio-paper, paper, bio-gas, and bio-diesel. The model could assist decision makers to identify the sub-industries in the EIT that would promote sustainability in the oil palm industry.

Cost-Benefit and Greenhouse-Gases Mitigation of Food Waste Composting: A Case Study in Malaysia

Waste generation nowadays is rising in the world and it seems hard to prevent it. Municipal Solid Waste (MSW) has been a major problem worldwide, especially in the fast growing cities and towns in the developing countries. This study aims to estimate the cost benefit and mitigation of greenhouse gases (GHGs) by converting the on-campus food and green waste generated in Universiti Teknologi of Malaysia (UTM) campus to compost. This study calculated the costing which includes the transportation, operating and equipment costs if green and food waste were converted into compost. The analyses were made with the basis of the pilot scale operation in Phase I operation. Extrapolation was made to project the further four phases of composting with higher amount of waste to estimate the potential profit. The results obtained from this study indicated that composting has the potential to generate a significant profit of Malaysia Ringgit (MYR)1.6 M/y based on 2,700 t/y of food and green waste composted. At the same time, the total solid waste supposedly to be sent to the landfill can be reduced by at least 47 %. Moreover, this study revealed that the composting process is able to reduce the GHGs emission rate by 90 %, i.e. the GHGs produced by the composting process is shown to be only 10 % of the total GHGs produced by landfill dumping given the same amount of solid waste to be disposed at the landfill site.

A Linear Programing Approach for Landfill Gas Utilization for Renewable Energy Production

Landfill gas (LFG) is a mixture of gases mainly CH4 and CO2 which are the most problematic of the greenhouse gases (GHGs) due primarily to their highest rate of accumulation in the environment. These two main GHGs are emitted from most landfills in developing countries. As a mitigation measure, the gases can be collected and utilized as renewable energy source. This research therefore aimed at planning the utilization of LFG for renewable energy production using linear programing approach executed in general algebraic modeling system (GAMS) and applied to Seelong landfill in Johor, Malaysia as the case study. GAMS (the optimizer) selects the most profitable LFG utilization technology from a number of options such as: gas engine, gas turbine and steam turbine for electricity or combined heat and power production; steam boiler for steam production; direct LFG distribution to residences/industries as substitutes to natural gas. The results from the optimizer gave a maximum profit of USD2.54 million per year. This included revenues from product sale and carbon credit. The results also revealed that GHG reduction of about 9,000 tons CO2eq were accomplished, and thus this is environmentally and economically beneficial environmentally (in terms of carbon credit). Furthermore, the optimization results revealed that steam turbine running on low grade LFG is the most feasible option in terms of profitability and environmental consideration. This approach can be applied to any sanitary landfill as a means of simultaneously curbing GHG emission and generating revenue.

A review on the impacts of compost on soil nitrogen dynamics

With the depletion of soil quality, the increased use of inorganic fertiliser is required to cope with the increasing food demand. The increasing use of inorganic fertiliser has become a burden to both the economy and environment. The overuse of nitrogen fertiliser can cause the leaching of NO3- to the surrounding water source and the emissions of N2O and NO to the atmosphere. Besides the environmental issues associated with conventional farming, more attention has been drawn to the rapid population growth and urbanisation that has led to the production of abundant municipal solid waste (MSW). To overcome these problems, composting can be an alternative option to both managing MSW and replacing inorganic fertiliser. As a biological process, composting can utilise the organic fraction of MSW as the raw material to produce compost, a stable form of organic matter that can be used as soil amendment or organic fertiliser. Although the utilisation of compost as an organic fertiliser is quite well studied, less research had focused on the nitrogen dynamic after compost application to soil. It is essential to figure out the correlation between compost application and soil nitrogen dynamic in order to prevent further nitrogen loss as a pollutant after compost application. This paper reviews the soil nitrogen cycle and the potential of nitrogen loss prevention with the application of compost. The application of compost is providing some promising effects in term of soil organic carbon and nutrients replenishment and soil microbial population enhancement. The effects of compost to soil are highly dependent on the characteristics of the raw materials for composting. The presence of high nutrient in compost is not always a good thing since it also increases the risk of nutrient loss through leaching or gas emission. The combination between nutrient rich and nutrient poor compost can be an alternative way to prevent nutrient loss. N2O emission from soil is always associated with high nitrogen content and anaerobic condition in soil. The mitigation of N2O emission can be achieved by compost application, and the addition of biochar during composting process can further enhance the effect.