Design of biomass value chains that are synergistic with the food-energy-water nexus: strategies and opportunities

Humanity’s future sustainable supply of energy, fuels and materials is aiming towards renewable sources such as biomass. Several studies on biomass value chains (BVCs) have demonstrated the feasibility of biomass in replacing fossil fuels. However, many of the activities along the chain can disrupt the food–energy–water (FEW) nexus given that these resource systems have been ever more interlinked due to increased global population and urbanisation. Essentially, the design of BVCs has to integrate the systems-thinking approach of the FEW nexus; such that, existing concerns on food, water and energy security, as well as the interactions of the BVCs with the nexus, can be incorporated in future policies. To date, there has been little to no literature that captures the synergistic opportunities between BVCs and the FEW nexus. This paper presents the first survey of process systems engineering approaches for the design of BVCs, focusing on whether and how these approaches considered synergies with the FEW nexus. Among the surveyed mathematical models, the approaches include multi-stage supply chain, temporal and spatial integration, multi-objective optimisation and uncertainty-based risk management. Although the majority of current studies are more focused on the economic impacts of BVCs, the mathematical tools can be remarkably useful in addressing critical sustainability issues in BVCs. Thus, future research directions must capture the details of food–energy–water interactions with the BVCs, together with the development of more insightful multi-scale, multi-stage, multi-objective and uncertainty-based approaches

Ni-based catalyst supported on mesostructured silica nanoparticles (MSN) for methanol oxidation reaction (MOR)

A new catalyst based on mesostructured silica nanoparticle (5wt%, 20wt%, and 30wt% Ni-MSN) were prepared by the wet impregnation method and used for electro-oxidation of methanol. While, MSN as a catalyst support was synthesized using co-condensation and sol-gel method. The synthesized MSN and Ni-MSN were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Fourier Transform Infra-red (FTIR) techniques. Ni-MSN catalysts were successfully prepared by mixing with the conducting graphite in 1:1 ratio which called carbon paste electrode (CPE). Mixing with graphite, in this work, was particular necessary to increase the electrical conductivity of the Ni-MSN materials. For fuel cell applications, the electrochemical measurements for methanol oxidation were investigated using cyclic voltammetry (CV) and chronoamperometry (CA) in 1.0 M NaOH and 1.0 M CH3 OH for modified electrode, Ni-MSNCPE. Among the three samples, 30wt% Ni-MSNCPE exhibits a high current density (~ 8 mA cm-2) and long-term chronoamperometry stability (3600 s) toward methanol oxidation in alkaline solution. This may attribute to the high dispersion of nickel and ordered mesoporous structure which can facilitate the diffusion of methanol and products. 30wt% Ni nanoparticles supported onto MSN catalyst demonstrate better electrocatalytic activity and stability than the 5wt% and 20wt% Ni-MSNCPE catalysts

Microstructure and Discharge Performance of Aluminum Al 6061 Alloy as Anode for Electrolyte Activated Battery

Electrolyte activated battery finds its important use during natural disaster emergencies, such as floods and typhoons. Nevertheless, high corrosion rate will deteriorate the discharge performance of the battery and it is influenced by the type of electrolyte and discharge current. In this study, the corrosion and discharge performance of a commercial Al 6061 aluminum alloy as an anode are investigated at different discharge currents (0.001, 0.01, and 1 mA) and in different electrolytes, namely salt water, urea, and distilled water. Scanning electron microscopy results show that electrode in salt water has the most serious corrosion, followed by that of in urea and in distilled water. These electrodeelectrolyte combinations are further investigated with potentiodynamic polarization, galvanostatic discharge, and electrochemical impedance spectroscopy (EIS) to understand their discharge potential, discharge behavior, and corrosion mechanism. Among all combinations, aluminum in water is found to have the highest discharge performance with discharge potentials ranging from 716 to 744 mV, regardless of discharge current

Optimization of oil palm empty fruit bunches value chain in Peninsular Malaysia

Empty fruit bunches (EFB) are valuable palm oil mill waste that could be used to produce multiple products in the form of energy, chemicals, and materials. Therefore, efficient utilization of these biomass resources is essential to optimize the profitability of the industry while addressing environmental issues. In this study, a decision-support tool is developed to perform economic and environmental analyses of the future expansion of the palm oil industry. The sequential steps in the modeling and optimization of the EFB value chain are discussed. This study consists of four processing stages: converting EFB into intermediates and products, transportation networks, direct sale of products, and further processing of products. The proposed tool includes a mathematical model that considers biomass, production, transportation, and emission treatment costs from transportation and production activities. The model is solved with the Advanced Interactive Multidimensional Modeling System to determine the maximum profit and analyze biodiesel production. Peninsular Malaysia is selected as a case study. Results reveal the significant economic benefits of EFB utilization. The most profitable cases of EFB utilization are Case A, C, and D, which have the same 47 % profit margin. The maximum profit of the selected utilization pathways in Case A is USD 151,822,904 per year based on different ownerships of all EFB processed, which is 79 % lower than the result of a previous study that ignores the capacity limitations of the respective processing facilities. The environment–food–energy–water nexus is also elaborated in this study. The conclusions are obtained based on the limitation, availability, and parameters or data used in this study

Catalytic decomposition of methane into hydrogen and carbon nanotubes over mesostructured silica nanoparticle-supported nickel catalysts

Hydrogen is an alternative source of renewable energy that can be produced by methane decomposition without any COx formation. In this work, an impregnation method was used to prepare a set of Ni-based catalysts (5% to 50%) supported on mesostructured silica nanoparticles (MSNs) for its application in methane decomposition. The use of MSN as an effective support for nickel in methane decomposition was reported here for the first time. The physical, chemical and structural properties of the catalysts was studied and the results indicated that NiO was the active species in the fresh catalyst that were effectively distributed on the mesoporous surface of MSN. The reduction temperature of Ni/MSN catalysts were shifted to low temperatures with increased loading of nickel. The hydrogen yield increased with the increment of Ni amount in the catalysts. The catalytic activity of the 50% Ni/MSN catalyst showed that this catalyst was highly efficient and stable compared with other catalysts. The catalyst showed the highest hydrogen yield of 68% and remained more or less the same during 360 min of reaction. Approximately 62% of hydrogen yield was observed at the end of reaction. Further analysis on the spent catalysts confirmed that carbon nanotubes was formed over Ni/MSN catalyst with high graphitization degree

Modelling and Optimisation of Oil Palm Biomass Value Chains and the Environment–Food–Energy–Water Nexus in Peninsular Malaysia

This study aims to develop a decision model to optimise the oil palm biomass value chains by minimising the environmental impact whiles generating economy value from their bioproducts. The model considers two major components, namely, a fuzzy analytic hierarchy (FAHP) framework and a multi-objective optimisation model. Both components will be used by integrating the priorities of the environmental and economic impacts obtained from experts' judgement with the multi-objective optimisation model to generate an optimal solution based on expert's judgement. The framework used to study different case study for the oil palm industry in Peninsular Malaysia. Results show that a maximum profit of 267,116,398 USD per year can be achieved. However, to minimise the environmental impact, a 34% cut of the profit is needed to reduce 91% of CO2 emissions generated and 97% of water consumption. Moreover, the model generates optimal pathways by selecting the processing facilities that are needed in the value chain to achieve the objectives. The biomass or bio-product distribution networks around Peninsular Malaysia are also presented in this paper. Several scenarios are discussed to observe the effects on the optimal value chain solutions by manipulating the production level. On the basis of the results, the interactions of the environment–food–energy–water nexus are investigated. Therefore, this study can contribute to the improvement of oil palm industry policies while addressing sustainability issues through the proposed value chain model

Sustainable bio-economy that delivers the environment-food-energy-water nexus objectives: the current status in Malaysia

Biomass is a promising resource in Malaysia for energy, fuels, and high value-added products. However, regards to biomass value chains, the numerous restrictions and challenges related to the economic and environmental features must be considered. The major concerns regarding the enlargement of biomass plantation is that it requires large amounts of land and environmental resources such as water and soil that arises the danger of creating severe damages to the ecosystem (e.g. deforestation, water pollution, soil depletion etc.). Regarded concerns can be diminished when all aspects associated with palm biomass conversion and utilization linked with environment, food, energy and water (EFEW) nexus to meet the standard requirement and to consider the potential impact on the nexus as a whole. Therefore, it is crucial to understand the detail interactions between all the components in the nexus once intended to look for the best solution to exploit the great potential of biomass. This paper offers an overview regarding the present potential biomass availability for energy production, technology readiness, feasibility study on the techno-economic analyses of the biomass utilization and the impact of this nexus on value chains. The agro-biomass resources potential and land suitability for different crops has been overviewed using satellite imageries and the outcomes of the nexus interactions should be incorporated in developmental policies on biomass. The paper finally discussed an insight of digitization of the agriculture industry as future strategy to modernize agriculture in Malaysia. Hence, this paper provides holistic overview of biomass competitiveness for sustainable bio-economy in Malaysia

Hydrogen storage alloys for remote area power supply

To supply electricity to a remote area community from national power grids is expensive and technically difficult. One of the possible solutions is to build a self-sustaining power generation system by harvesting the free renewable energy. However, the key issue to address in utilizing renewable energy is its intermittent nature that cannot guarantee a non-interruptible power supply at all time. Hence, this work proposed to store the energy in the form of hydrogen because of its superior energy density. The excess energy from renewable energy source is converted to hydrogen energy via electrolysis. The hydrogen is stored and used by the fuel cells to generate electricity. Nevertheless, hydrogen has a very low density at ambient pressure and temperature, which increases the complexity to store it in safe and economical manner. Metal hydrides can be used to address this issue because of its extremely high volumetric hydrogen storage capacity. The aim of this work was to develop a new type of alloy that can be used in Remote Area Power Supply (RAPS). The designed alloys should have a hydrogen storage capacity of more than 1.00 wt% and have a capability to store and reverse the hydrogen within the pressure range of 0.10 to 1.00 MPa at room temperature. In addition to the fast absorption kinetics (less than 100 s for 1 g of sample), the alloy should also have the capability to retain at least 50% of hydrogen storage efficiency with at least 1.00 wt% of hydrogen storage capacity after 500 charge-discharge cycles. It is expected that the newly designed alloys can save at least 10% of raw materials cost as compared to the AB5 type alloys.In this work, La-Mg-Ni based AB3 type Hydrogen Storage Alloy (HSA) was selected as the candidate. It was found that the hydrogen storage capacity was 1.67 wt%. An AB5 HSA has also been chosen for comparison. The hydrogen storage capacity of the La-Mg-Ni based AB3 was approximately 40% higher than the conventional AB5 type alloys. The effects of partial substitutions of both Ce and Al on the hydrogenation properties of La(0.65-x)CexCa1.03Mg1.32Ni(9-y)Aly were investigated simultaneously using factorial design. Both Ce and Al additions greatly improve the reversibility of hydrogen storage capacity. However, the maximum hydrogen storage capacity and absorption kinetics can be affected by the additions. As Ce and Al give opposite effects on the absorption and desorption plateaus, response surface methodology can be used to tune and optimize the properties of the HSA to the desired operating conditions for fuel cell applications. The Johnson-Mehnl-Avrami-Kolmogorov model was used to understand the kinetics and hydrogen absorption mechanisms of La-Mg-Ni based HSA. Nonetheless, the experimental data cannot fit into the model with a single slope line, demonstrating that there was more than one mechanism operating. Hence the results were split into two regions according to their slopes. The results showed that the dominant rate-limiting step of samples with Al addition were interface-controlled absorption. On the other hand, a diffusion-controlled reaction is applicable to all other fast absorbing samples, as well as the second region of the absorption where hydrides formation are closed to saturation. The effects of Ce and Al on the cycle stability of the La-Mg-Ni based HSA have also been investigated. The cycle stability was mainly enhanced by Al additions; unfortunately excessive addition of Al deteriorated the hydrogen storage capacity unanimously. Hence, even though La-Mg-Ni based HSA is more price-competitive than AB5 type HSA, its commercial readiness is limited by its efficiency. A hybrid system between AB5 type and La-Mg-Ni based HSA could be a solution. This work indicated that a composite with 50 wt% of each type of HSA had a superior cycle stability with a reasonable capacity retention and operating pressure plateaus, as well as, a 10% cost saving in raw materials. This work has successfully demonstrated the viability of HSA as the energy storage medium for RAPS application

Techno-Economic Analysis of an Integrated Bio-Refinery for the Production of Biofuels and Value-Added Chemicals from Oil Palm Empty Fruit Bunches

Lignocellulose-rich empty fruit bunches (EFBs) have high potential as feedstock for second-generation biofuel and biochemical production without compromising food security. Nevertheless, the major challenge of valorizing lignocellulose-rich EFB is its high pretreatment cost. In this study, the preliminary techno-economic feasibility of expanding an existing pellet production plant into an integrated bio-refinery plant to produce xylitol and bioethanol was investigated as a strategy to diversify the high production cost and leverage the high selling price of biofuel and biochemicals. The EFB feedstock was split into a pellet production stream and a xylitol and bioethanol production stream. Different economic performance metrics were used to compare the profitability at different splitting ratios of xylitol and bioethanol to pellet production. The analysis showed that an EFB splitting ratio below 40% for pellet production was economically feasible. A sensitivity analysis showed that xylitol price had the most significant impact on the economic performance metrics. Another case study on the coproduction of pellet and xylitol versus that of pellet and bioethanol concluded that cellulosic bioethanol production is yet to be market-ready, requiring a minimum selling price above the current market price to be feasible at 16% of the minimum acceptable return rate

Investigation of palladium-mesostructured silica nanoparticles (Pd-MSN) as anode electrocatalyst for alkaline direct methanol fuel cell

The commercialization of fuel cells is hindered by the high cost of noble metal electrocatalysts, such as platinum. Mesostructured silica nanoparticles (MSNs), as a novel catalyst support, are added to active palladium nanoparticles to create a Pd-MSN electrocatalyst with low Pd content to improve catalytic efficacy and decrease costs. Wet impregnation method was used to prepare catalysts that comprise palladium nanoparticles supported on MSNs (i.e. 5 wt% Pd-MSN, 10 wt% Pd-MSN, 15 wt% Pd-MSN, 20 wt% Pd-MSN and 20 wt% Pd-C) to enhance electrocatalytic activity for methanol oxidation. The structures of the catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) and Brunauer–Emmet–Teller (BET) surface area analysis, and their electrocatalytic performance towards methanol oxidation was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). Amongst the catalysts, 20 wt% Pd-MSN has the highest electrocatalytic activity (14.3 mA cm−2) and stability (3600 s) for methanol oxidation in alkaline medium at the constant potential of −0.2 V. This result indicates that 20 wt% Pd-MSN may be a promising anode material for direct methanol fuel cells. The improved electrocatalytic activity and stability of the electrocatalyst are attributed to the high specific surface area of MSN and the effective surface structure of Pd nanoparticles. Furthermore, MSN increases catalyst dispersion by producing new active sites, which results in the promotion of Pd utilization