• Energy Research
• Closed Access close
• Restricted close
• 13. Climate action close
• 11. Sustainability close
• 6. Clean water close
• MY close

Among various bioreactors examined in anaerobic digestion and dark fermentation, UASB bioreactor has shown to be a promising alternative. However, mass transfer resistance and biomass washout have been the issues that reported as draw backs of the granular system in the literature. Another problem associated with such a system is its long start-up period as a result of biomass washout and long microbial granulation stage. In this paper, the results obtained from an UASFF bioreactor in methane (AD process) and hydrogen (DF process) production from POME, are presented to assess mass transfer of substrate into the granules and also study the role of internal packing used in the middle part of reactor in the process stability. The value of effectiveness factor, η, for AD and DF processes were calculated to be 0.96 and 0.94, respectively, indicating that there was no mass transfer resistance due to internal and/or external factors. The results showed that the packing material could retain biomass in the reactor and had outstanding contribution in the granulation enhancement. Its role as a supplementing treatment stage was more significant at low HRTs and up-flow velocities.

Landfill gas (LFG) is essentially greenhouse gas (GHG) composed predominantly of methane and carbon dioxide produced from the anaerobic biodegradation of municipal solid waste in landfills. The amount of gas produced can be estimated using the Intergovernmental Panel on Climate Change methodology. Most sanitary landfills flare this potential renewable energy source, which is an unfortunate waste of a valuable resource. This study develops an optimization model for effective LFG utilization as a sustainable energy source based on economic and environmental considerations. The mixed integer linear programming model developed was applied to Seelong Sanitary Landfill, Malaysia, and led to profits 7.6 times higher than those currently gained. This enormous increase is due to the incorporation of renewable energy production in the new plan. In addition, the combined heat and power generation proposed is 2420 tons of oil equivalents, which is 0.0035% of the total energy production of Malaysia. Similarly, the LFG utilization leads to a national GHG reduction of 0.007%. Implementing this at the 14 sanitary landfills in the country will go a long way towards broadening the energy base while simultaneously reducing the carbon footprint of the nation. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 289–296, 2015

Abstract The development of predictive mathematical models for water management in polymer electrolyte membrane fuel cells requires detailed understanding of water distribution and water transport across the Nafion layer. The anisotropic microstructure of Nafion suggests the measurement of water content and mass transport should be along the fuel cell functional direction, i.e. across the membrane. Non-invasive, high resolution, microscopy measurements of this type are very challenging. We report here the calibration of a minimal mathematical model for diffusive water transport in Nafion against data from high-resolution water content maps determined with a new magnetic resonance imaging methodology developed for this purpose. A mock fuel cell was designed to permit well-controlled wetting and drying boundary conditions. With no chemical potential driving force involved, we assume the water transport behavior will be dominated by diffusion. Moreover we show that, in this context, our model is mathematically equivalent to the traditional permeation models based upon saturation dependent pressure gradients via a capillary pressure ansatz. The non-linear equilibrium water distribution across the Nafion membrane measured in this work suggests a bi-modal diffusivity. The model constructed associates distinct transport behaviors to water contents above and below a critical threshold, consistent with a rearrangement of a micro-structural pore network. The experimental observation and the model prediction agree with the primary features of Weber's model of Nafion, which predicts distinct modes of transport for hydration fronts traversing the through-plane direction of the membrane.

Environmental quality indicators are crucial for responsive and cost-effective policies. The objective of the study is to examine the relationship between environmental quality indicators and financial development in Malaysia. For this purpose, the number of environmental quality indicators has been used, i.e., air pollution measured by carbon dioxide emissions, population density per square kilometer of land area, agricultural production measured by cereal production and livestock production, and energy resources considered by energy use and fossil fuel energy consumption, which placed an impact on the financial development of the country. The study used four main financial indicators, i.e., broad money supply (M2), domestic credit provided by the financial sector (DCFS), domestic credit to the private sector (DCPC), and inflation (CPI), which each financial indicator separately estimated with the environmental quality indicators, over a period of 1975-2013. The study used the generalized method of moments (GMM) technique to minimize the simultaneity from the model. The results show that carbon dioxide emissions exert the positive correlation with the M2, DCFC, and DCPC, while there is a negative correlation with the CPI. However, these results have been evaporated from the GMM estimates, where carbon emissions have no significant relationship with any of the four financial indicators in Malaysia. The GMM results show that population density has a negative relationship with the all four financial indicators; however, in case of M2, this relationship is insignificant to explain their result. Cereal production has a positive relationship with the DCPC, while there is a negative relationship with the CPI. Livestock production exerts the positive relationship with the all four financial indicators; however, this relationship with the CPI has a more elastic relationship, while the remaining relationship is less elastic with the three financial indicators in a country. Energy resources comprise energy use and fossil fuel energy consumption, both have distinct results with the financial indicators, as energy demand have a positive and significant relationship with the DCFC, DCPC, and CPI, while fossil fuel energy consumption have a negative relationship with these three financial indicators. The results of the study are of value to both environmentalists and policy makers.

Abstract Catalytic co-liquefaction of high-density polyethylene and sugarcane bagasse over metal salt and oxide catalysts in ethanol solvent was investigated. The obtained bio-oil samples were analyzed and characterized by gas chromatography–mass spectroscopy (GC–MS), nuclear magnetic resonance (NMR), ultimate analysis (CHNS/O), Fourier transform infrared spectroscopy (FTIR) and different solid products characterized by x-ray fluorescence (XRF) and Scanning Electron Microscope (SEM) analysis. The results suggested that adding ZnSO4 gives the highest HHV (34.61 MJ/kg), while CuSO4 gives the highest bio-oil yield (38.42 %) and conversion (69.54 %). GC–MS analysis suggested that the bio-oils contained large amounts of hydrocarbons, phenols, ketone aldehydes, alcohols and esters. The 1H and 13C NMR spectra were integrated over spectral regions to quantify classes of carbon and hydrogen atoms in each bio-oil and suggested that bio-oils largely contain alkanes, aliphatics and alcohols. The liquid products are promising bio-fuel precursors for further utilization.

Abstract Global energy consumption is increasing at a dramatic rate and will likely continue to do so. The major source of energy is still fossil fuel, which has resulted in the well-documented problem of global warming due to the emission of greenhouse gases from the burning of such fuel. Climate change and global warming are among the crucial and complex issues encountered by the world today, and they require an immediate solution. Technological innovation is the key to ensuring energy security without causing emissions and providing efficient cost-effective energy solutions. Power electronic technologies offer high reliability and renewable energy conversion efficiency, thus contributing to energy conservation, improving energy efficiency, and helping in the mitigation of harmful global emissions. This review focuses on various aspects of power electronic technologies and their importance in tackling carbon emission and global warming problems. The key topologies of power electronic converters are explained based on types, control difficulties, benefits, and drawbacks. Power electronic controllers utilized for energy conversion are comprehensively reviewed with regard to their structure, algorithm complexity, strengths and weaknesses, and mathematical modeling. The review focuses on power converters and controllers used in different applications and highlight their contributions to energy conservation, increasing the share of renewable energy sources, and mitigating emissions. Moreover, existing research gaps, issues, and challenges are identified. The insights provided by are expected to lead to the enhanced development of advanced power electronic converters and controllers for sustainable energy conversion. Such development can reduce carbon emissions and mitigate global warming.

Sustainable energy system design offers credible and innovative strategies to overcome environmental energy crises. Solar walls offer feasible technique for the exploitation of directional flow of heat in buildings. This article reviewed state-of-the-art concepts, applications and significance of solar walls for energy savings in buildings. Detailed operational framework of various solar-wall configurations, technology and efficiency as building component was discussed. Need for this sustainable energy design in buildings and constraints associated with their realisation were reported to aid proposed future research work.

This paper presents the development of a new systematic technique for the retrofit of water network with regeneration based on water pinch analysis. The procedure consists of two parts: retrofit targeting and design for a water network with regeneration unit(s). In the targeting stage, retrofit targets (utility savings and capital investment) were determined for a range of process parameters (total flowrate and/or outlet concentration of the regeneration unit) to obtain a savings versus investment curve. Next, the existing water network was re-designed to meet the chosen targets. A case study on paper making process was used to demonstrate the new methodology.

Abstract In this study, a hybrid system for potential electricity generation for Rohingya refugees in Kutupalong camp, Ukhia, Cox’s Bazar, Bangladesh is investigated. Six scenarios are considered, and an optimal configuration is chosen based on low cost of energy and low emission. The optimum system consists of a combination of Generator/PV Panel/Wind/Converter/Battery. The configuration has cost of energy of 0.35$ per kW, and the renewable fraction is found to be 87%. The proposed system is also environmentally friendly and the optimum system discharges less than 65%, 84%, and 61% emission when compared with grid, diesel, and kerosene respectively. From sustainability indicators, it was observed that the amount of diesel needed to be imported is 30%. Therefore, dependency on import is less, and this makes the proposed system highly reliable. Besides, this system does not use biomass to generate electricity. 87% resources come from renewable energy sources. So this system is highly sustainable. There is literally no idle time for equipment since their deployment is according to the demands of people. This idle time of equipment causes depreciation which in turn leads to less efficiency and higher cost.