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Abstract Double and added double stage organic Rankine cycle systems are configured to recover exhaust gas waste heat of dual fuel engines. To evaluate the performance of the models proposed here, energy, exergy and economic analyses are performed. Several working fluids are evaluated for recommendation for double and added double stage organic Rankine cycle systems. In the double stage organic Rankine cycle, cycle 1 and cycle 2 are connected in parallel. Working fluids R123, R141b, and R601 are used in cycle 1, and R245fa, R236ea, and R1233zd in cycle 2. In the double stage organic Rankine cycle, the working fluid combinations of R601-R1233zd, R601-R245fa and R123-R245fa show better performance when considering power, heat transfer area and payback period, which are 1760 kW, 2108.9 m2 and 4.21 year, respectively for R601-R245fa. In the added double stage organic Rankine cycle, cycle 1 and cycle 2 are connected in two stages and cycle 1 and cycle 3 in parallel. The net power of the working fluid combinations of R123-R245fa and R123-R1233zd are 1799 kW and 1782 kW, respectively, which are higher than those of the others. Further, for R123-R245fa, the heat transfer area and payback period are 3352 m2 and 6.20 year, respectively, which is better compared to those of other working fluid combinations.

Abstract Hydrogen is considered a potential game changer for world energy systems and a solution to climate change concerns, as it generates zero waste and it is suited for power generation and transportation. Despite its several advantages, there are significant technical challenges in deploying a stable hydrogen economy including improving its process efficiencies, lowering production costs, maintaining cost-effective transmission and distribution, and exploiting inexpensive and sustainable feedstocks. In this context, a detailed study was conducted to analyze the production sources, technologies, storage and transport systems, and global potential exportable feedstocks to produce hydrogen. A comprehensive analysis of current hydrogen production technologies with their energy efficiencies and hydrogen selling prices was reported in this study. Various hydrogen production technologies with their capital investments and CO2 emissions were also presented. Potential feedstocks for hydrogen production were identified and analyzed through a product space model, which characterizes a network of global exportable products based on their similarities and productive knowledge. It was established that the hydrogen production feedstocks and sources currently used are primarily available in six countries: the United States of America, France, Russia, Sweden, the Netherlands, and Spain. Broadly, the results revealed that the United States of America and Russia shared the highest hydrogen feedstock exports, indicating a higher probability of hydrogen production in these countries. Except for Russia, all the studied countries fell in the most desired quadrant, indicating that they can move in all product space directions to exploit unexplored hydrogen feedstocks for better sustainable economic growth.

Abstract In order to improve the accuracy, validity, reliability and reproducibility of reported power conversion efficiencies for solar cells, the journal, Solar Energy Materials and Solar Cells (SOLMAT), wishes to define how power conversion efficiencies should be reported. This expands upon what is specified in our Guide for Authors. This editorial also serves as a guide on how efficiency data should be checked within the reporting laboratory before sending cells or materials for testing at an independent laboratory. The threshold where the accuracy of efficiency values is important to the journal is whenever power conversion efficiencies require external quantum efficiencies (EQE) values above 50% over a large range of wavelengths or when reported power conversion efficiencies exceed 2.5%. Extra care should be taken in submitted manuscripts to document the measurement's quality, relevance and independent verification.

SummaryWe conducted a decomposition analysis of material flows in a dynamic system, focusing on factors in the generation of waste consumer durables. A methodology for the analysis of consumer durables was developed and applied to three common consumer durables: cathode ray tube TVs, refrigerators, and passenger cars. The methodology decomposed changes in the numbers of waste products into three factors: changes in lifespan distribution, past trends in replacement sales, and past trends in sales for additional purchases. The decomposed equation clearly showed that the number of waste products would not necessarily be reduced by lifespan extension alone. This is because the number of waste products generated is affected not only by current lifespan distribution but also by past trends in sales for replacement and in additional purchases. The results show that changes in past replacement sales influence the current generation of waste, even if current replacement sales are declining. To reduce the generation of waste products on a short‐term basis, lifespan must be extended until the waste‐reducing effect of lifespan extension exceeds the waste‐increasing effect of the other two factors. From a long‐term perspective, controlling current replacement and additional purchases can be used to prevent future waste product generation.

Abstract Waste heat recovery has attracted a significant attention because of the world growth in energy demand. In this paper, we report the study on an energy recovery system utilizing low-grade waste heat below 100 °C. This system called a thermal-driven electrochemical generator is composed of reverse electrodialysis (RED) power generation and thermal separation using waste heat. We especially focus on the experimental characterization of the RED process with ammonium bicarbonate (NH4HCO3) solution, which is known to be easily decomposed at the temperature around 60 °C. We characterized this NH4HCO3-RED system with various parameters including the concentration difference, the membrane type, the inlet flow rate, and the compartment thickness. We found the best power density at the concentrated solution of 1.5 mol L−1 and the diluted solution of 0.01 mol L−1. The maximum power density increases as the inlet flow rate increases or the compartment thickness decreases owing to the decrease in the internal resistance. We obtained the excellent power density of 0.77 W m−2, compared with the previous studies.

Abstract This paper attempts to measure consumers' perceived net benefits (or net costs) of energy-saving measures in using energy-consuming durable goods. Using the estimated net costs and the volume of CO2 reduced by the measures, a marginal abatement cost (MAC) curve for the average household's CO2 emissions is produced. An analysis using the curve suggests that in order to provide households with an incentive to take actions that can lead to CO2 emission reductions in using energy-consuming durables, a high level of carbon price is needed. In addition, a regression analysis reveals that the net benefits of the measures are larger for households that put a higher priority on energy saving, for those living in detached houses, for those with a smaller number of persons living together, and for those with less income. The result of the analysis using the MAC curve may suggest that promoting energy-saving behavior will require not only a policy to provide economic incentives but also interventions to influence psychological factors of household behavior.

This study presents an investigation on the influence of hydrothermally treated municipal solid waste (MSW) on the co-combustion characteristics with different rank coals, i.e. Indian, Indonesian and Australian coals. MSW blends of 10%, 20%, 30% and 50% (wt.%) with different rank coals were tested in a thermogravimetric analyser (TGA) in the temperature range from ambient to 700 °C under the heating rate of 10 °C/min. Combustion characteristics such as volatile release, ignition and burnout were studied for the blend fuel. Different ignition behavior was observed depending on the blends composition and the coal rank. The result of this work indicates that the blending of MSW improves devolatization properties of coal. But it was found that the co-combustion characteristics of MSW and coal blend cannot be predicted only from the pyrolytic and or devolatization phenomena as the other factors such as the coal quality also plays a vital role in deciding the blends co-combustion characteristics. The TGA combustion profiles showed that the combustion characteristics of blends followed those of parent fuels in both an additive and non-additive manners. These experimental results help to understand and predict the behavior of coal and MSW blends in practical applications.

A balance between industrial pollution and economic growth becomes a major policy issue to attain a sustainable society in the world. To discuss the problem from economics and business perspectives, this study proposes a new use of DEA (Data Envelopment Analysis) as a methodology for unified (operational and environmental) assessment. A unique feature of the proposed approach is that it separates outputs into desirable and undesirable categories. Such separation is important because energy industries usually produce both desirable and undesirable outputs. This study discusses how to unify the two types of outputs under natural and managerial disposability. The proposed DEA approach evaluates various organizations by the three efficiency measures such as OE (Operational Efficiency), UEN (Unified Efficiency under Natural disposability) and UENM (Unified Efficiency under Natural and Managerial disposability). An important feature of UENM is that it separates inputs into two categories and unifies them under the two disposability concepts in addition to the proposed output separation and unification. This study incorporates an amount of capital assets for technology innovation, as one of the two input group, into the measurement of UENM. Then, it compares UENM with the other two efficiency measures. This study is the first research effort in which DEA has an analytical capability to quantify the importance of investment on capital assets for technology innovation. To confirm the practicality of the proposed approach, this study applies the three efficiency measures to a data set regarding manufacturing and non-manufacturing industries of 47 prefectures in Japan. This study empirically confirms the validity of Porter hypothesis in Japanese manufacturing industries, so implying that environmental regulation has been effective for betterment on the performance of Japanese manufacturing industries. Another important finding is that the emission of greenhouse gases is a main source of unified inefficiency in the two groups of industries. Therefore, Japanese industries, examined in this study, need to make their efforts to reduce the greenhouse gas emissions and air pollution substances by investing in capital assets for technology innovation.

Abstract Rice husk (RH), an agricultural waste, is abundantly available in rice producing countries like China, India, Bangladesh, Brazil, US, Cambodia, Vietnam, Myanmar, and South East Asia. Despite the massive amount of annual production worldwide, so far RHs have been recycled only for low-value applications. In recent years, many rice mills in rice producing countries have started using RH for the energy production for mill operations as well as household lighting in rural regions. Burning of RHs produces the rice husk ash (RHA). The disposal in landfills or open fields can be problematic and may cause a serious environmental and human health related problems due to the low bulk density of RHA. Several ways are being thought of for disposing RHA by making its commercial use. The amorphous silica forms the main component (83–90%) of RHA. The amorphous silica rich RHA has wide range of applications. High-value applications and current research investigations such as the use of RHA in manufacturing of silica gels, silicon chip, synthesis of activated carbon and silica, production of light weight construction materials and insulation, catalysts, zeolites, ingredients for lithium ion batteries, graphene, energy storage/capacitor, carbon capture, and in drug delivery vehicles are presented. Use of RHA in potential future applications is also discussed. It is suggested that the amorphous silica rich RHA could become a potential resource of low cost precursor for the production of value-added silica based materials for practical applications.