Synthesis of Sustainable Circular Economy in Palm Oil Industry Using Graph-Theoretic Method

The P-graph approach in optimal synthesis and planning of waste management towards achieving sustainable development goals: A systematic review

Effective waste management remains a challenge in global environmental sustainability, underlining the urgent necessity for innovative solutions. This review explored waste management strategies, focusing on the role of P-graph frameworks in achieving sustainable development goals (SDGs). P-graphs offer a systematic approach across domains including, chemical reaction routes, carbon management networks, economic systems and resource planning to waste management synthesis and planning. Through a systematic search and analysis of relevant P-graph approaches, 28 articles meeting the inclusion criteria were selected for review. The study reveals that P-graph approach is a systematic methodology that can streamline decision-making processes, which ultimately lead to more efficient and effective waste management strategies and solutions. This research also highlighted the absence of previous studies on the application of the P-graph approach to various types of waste, underscoring its significance and originality in the field. This study seeks to advance the achievement of SDGs and promote sustainable waste management practices through the integration of the P-graph framework with waste management solutions.

Analysis of current state, gaps, and opportunities for technologies in the Malaysian oil palm estates and palm oil mills towards net-zero emissions

Malaysia is the second largest producer and exporter of palm oil. Though several works have explored achieving emissions reduction in the palm oil sector, there existing gaps in analysing pathways for achieving net-zero emissions. Moreover, there are limited studies that evaluate the potential of palm oil biomass utilisation pathways based on emissions reduction capabilities, the cost of emissions reduction, and the technology readiness for implementation. Therefore, this study analysed decarbonisation pathways for the upstream and midstream segments of the palm oil sector in Malaysia, encompassing oil palm plantations and palm oil mills. Various sources of greenhouse gas emissions in oil palm plantations and palm oil mills were identified and estimates of emissions were determined as theoretical emissions. The current emissions were established based on the current best practice in the plantation and mill. Several biomass conversion technologies for the recovery of palm-based by-products and conversion into value-added products to decarbonise the palm oil sector and evaluated strategies to attain net-zero status are considered. In this work, the analysis considered both the existing technologies that are adopted by plantations and mills as well as the emerging technologies that have scope for implementation. With the proposed approach, the current emissions level for crude palm oil (CPO) production in Malaysia is estimated as 1121.49 kg CO2-eq/t CPO. In current industry practice, empty fruit bunch (EFB) is underutilised as mills are typically located at rural areas with lack of suitable transportation. Besides, the lack of accessibility to the grid also limits the potential of converting EFB into electricity as supply for national grid. This work examined various pathways for EFB utilisation under different scenarios evaluating their contribution potential towards net-zero target in an energy self-sustained CPO production. As shown in the results, converting EFB to briquettes and pellets are able to achieve the net-zero objective. Furthermore, EFB-biochar and EFB-syngas pathways also exhibit the potential to accomplish the net-zero target. Note that this work also assessed the technologies' readiness levels, identified challenges in implementation, and proposed several recommendations.

A holistic mitigation model for net zero emissions in the palm oil industry

Achieving net zero emissions to ensure a sustainable future has become increasingly urgent in light of climate change. The palm oil industry in Malaysia plays a significant role in the country's economy but has faced criticism for its environmental impact, particularly in terms of sustainability and greenhouse gas emissions. While the government has implemented policies and initiatives to promote sustainable palm oil production and reduce emissions, there remains a need for a comprehensive and integrated mitigation strategy to help make an informed decision to improve the performance. To address the limitations of the current framework, this study proposes an Integrated Mitigation Strategy Model which incorporates established frameworks of Palm Oil Mill Carbon Accounting (POMCFA) and Sustainability Index (POMSI). This model has been developed based on the superstructure approach, considering a set of mitigation options to improve weak indicators identified through assessments. The selection of these options is informed by a theoretical review of existing literature on factor changes and their impact on emissions reduction. The model is further validated through case studies, ensuring its robustness and reliability. Based on the case study, it reveals that palm oil mill effluent, diesel consumption, and water consumption contribute the most to carbon dioxide equivalent emissions. In terms of sustainability scoring, the environmental aspect obtains the lowest scores compared to social and economic aspects. Weaknesses identified include dust concentration, palm oil mill effluent, and boiler emissions. Using the heuristics of factor changes equation, the mitigation model suggests implementing high-technology boilers as the optimal solution for these weaknesses. With the theoretical and empirical support behind the choice of variables, our model provides a valuable tool for decision-making in achieving net-zero emissions and sustainable palm oil production.

Synthesis of Integrated Flower Waste Biorefinery: Multi-Objective Optimisation with Economic and Environmental Consideration

The improper disposal of flower waste from cultural activities is one of the main challenges in certain countries such as India. If the flower waste is not managed properly, it causes a number of environmental issues. Therefore, various technologies have been developed to transform flower waste into value-added products. To integrate multiple technologies holistically to maximise the energy and material recovery, an integrated flower-waste biorefinery is required. Since there are a wide range of technologies available that can convert the waste into multiple products, there is a need to develop a systematic approach to evaluate all the technologies. This research proposes a systematic approach to synthesise an integrated flower-waste biorefinery based on different optimisation objectives, e.g., maximum economic performance and minimum environmental impact. Due to the conflicting nature between the two objectives, a fuzzy optimisation approach has been adapted to synthesise a sustainable integrated flower-waste biorefinery that satisfies both objectives at once. The efficacy of the proposed approach is demonstrated through a case study in India based on the optimised results with fuzzy optimisation—a synthesised flower-waste integrated biorefinery with economy performance of $400,932 and carbon emission of 46,209 kg CO2/h.

Logistics and Supply Chain Modelling for the Biobased Economy: A Systematic Literature Review and Research Agenda

One way to mitigate the negative impacts of climate change, is for society to move towards a biobased economy, where fossil resources are replaced by biobased ones. This replacement requires the development of biobased supply chains that differ significantly from the conventional supply chain. For example, seasonality and variability of the feedstocks create specific challenges for biobased systems and call for customized solutions for the design and operation of biobased chains. As a result, the modelling efforts to support decision-making processes for biobased logistics and supply chains have some different requirements. This paper presents a systematic literature review on logistics and supply chain modelling studies for the biobased economy published in a period of 2011–2020. The literature analysis shows that most modelling studies for the biobased economy are strategic optimization models aiming to minimize economic impact. As biomass source, forest and agricultural residues are mostly used, and fuel and energy are the most common biobased applications. Modelling strategies, biomass sources and applications are however diversifying, which is what we encourage for future research. Also, not only focusing on economic optimization but also optimizing social and environmental performance is an important future research direction, to deal with the sustainability challenges the world is facing.

Circular Economy Indicators for the Assessment of Waste and By-Products from the Palm Oil Sector

A circular economy (CE) promotes the reuse, reincorporation and valuation of waste and by-products under the framework of sustainable development through models and indicators that evaluate scenarios of second use and reduction in non-incorporated outputs to reduce negative externalities and pressures on the dimensions of development. A CE model applied to the transformation process of RFF in agro-industries is developed, which consists in the identification of the residue coefficients of EFB (22.48% ± 0.8), fiber (15.58% ± 0.49), husk (6.03% ± 0.66) and ash (0.55% ± 1.67). Subsequently, the valuation trends of potential second use were verified through a systematic review, which allowed the construction of the scenario of avoided costs of USD 678,721.5, a product of the total use of the outputs under bioenergy and nutrient source approaches. Finally, the RRSFM indicator was constructed, which can reach the level of 72% and a degree of improvement of 26% by 2026. In parallel, the HCRRS indicator revealed a reduction of 57.1%, 59.6% and 82.8% in emissions of t CO2-eq product in the comparison of scenarios for the use of residues and by-products of palm oil from agro-industries in the Casanare Department.

The Effects of Subsidies on MSW Treatment Companies: Financial Performance and Policy Implications

Companies that provide public services usually receive subsidies from municipalities as compensation for replacing the latter in their functions as public service providers. However, the managers of those companies are not always interested in maintaining an economically sustainable company, as this implies turning off the tap on exploration subsidies. This article investigates the effect of subsidies on the financial performance of municipal solid waste collection and treatment companies for 2016–2020 and across NUTS II regions. The accounting data of 680 companies retrieved from the SABI database, make it possible to assess the economic sustainability of the companies through financial ratios and operational data. The results show that the financial structure and management of companies in the Centro, Lisbon, and the Azores allowed to take advantage of exploration subsidies to achieve economic sustainability. In the remaining regions these subsidies proved to be ineffective. These results have implications for managers and policy makers insofar as it sheds a light on the conditions under which subsidies contribute to the economical sustainability of companies in the sector.

A Review of Process Systems Engineering (PSE) Tools for the Design of Ionic Liquids and Integrated Biorefineries

In this review paper, a brief overview of the increasing applicability of Process Systems Engineering (PSE) tools in two research areas, which are the design of ionic liquids and the design of integrated biorefineries, is presented. The development and advances of novel computational tools and optimization approaches in recent years have enabled these applications with practical results. A general introduction to ionic liquids and their various applications is presented followed by the major challenges in the design of optimal ionic liquids. Significant improvements in computational efficiency have made it possible to provide more reliable data for optimal system design, minimize the production cost of ionic liquids, and reduce the environmental impact caused by such solvents. Hence, the development of novel computational tools and optimization tools that contribute to the design of ionic liquids have been reviewed in detail. A detailed review of the recent developments in PSE applications in the field of integrated biorefineries is then presented. Various value-added products could be processed by the integrated biorefinery aided with applications of PSE tools with the aim of enhancing the sustainability performance in terms of economic, environmental, and social impacts. The application of molecular design tools in the design of integrated biorefineries is also highlighted. Major developments in the application of ionic liquids in integrated biorefineries have been emphasized. This paper is concluded by highlighting the major opportunities for further research in these two research areas and the areas for possible integration of these research fields.