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Abstract In this paper, energy and exergy analyses of the geothermal-based hydrogen production via thermochemical water decomposition using a new, four-step copper–chlorine (Cu–Cl) cycle are conducted, and the respective cycle energy and exergy efficiencies are examined. Also, a parametric study is performed to investigate how each step of the cycle and its overall cycle performance are affected by reference environment temperatures, reaction temperatures, as well as energy efficiency of the geothermal power plant itself. As a result, overall energy and exergy efficiencies of the cycle are found to be 21.67% and 19.35%, respectively, for a reference case.

Abstract China's carbon emissions have been ranking first in the world. This study filled in the gaps in research, decomposed carbon intensity from the perspective of time, space and industry. A decoupling effort model based on factor decomposition models was constructed to analyze the driving factors of carbon emissions and economic decoupling, which builded a foundation for achieving sustainable economic development. Using the Logarithmic Mean Divisia Index method (LMDI), the paper measured the carbon emission intensity of 29 provinces and cities in China from 1998 to 2019, and decomposed the decoupling effect between GDP and carbon emission on the basis of factor decomposition by tapio. The results showed that: (1) Carbon intensity declined first, then rise lightly, and finally declined steadily. For the primary industry and the tertiary industry, the carbon intensity declined steadily, while the carbon intensity increased accordingly to the overall carbon intensity. In terms of spatial evolution, the regional differences between different provinces decreased correspondingly. (2) The cumulative contribution rates of these three effects, i.e., technological progress, industrial structure and regional scale were 106.3299%, −15.1486% and 8.8188%, respectively. There were obvious differences of these cumulative contribution rates of carbon intensity among different provinces. (3) From the perspective of industrial, technological progress effect is the largest contribution for carbon intensity in the secondary industry. The Industrial structure effect mainly affects the primary and tertiary industries; and no significant difference in regional scale effect. (4) The decoupling effect gradually improved, and technological progress has played an absolute leading role in promoting the decoupling effect. Based on the research results, the key policy recommendation are put forward as follows: (1) Further improve the technological level and support clean technology enterprises. (2) Promote industrial upgrading in backward industrial provinces (3) Promote regional assistance and the introduction of high-quality foreign investment.

Abstract The city of Pecs in Hungary has developed an energy strategy to be implemented in the years to come which proposes structural changes in both the supply and demand sides. This paper offers a model based on the proposed system aimed at providing a basis for comparison for decision-makers. The model has been developed with the help of energy system analysis tool energyPRO, and covers the three basic sectors of heat, electricity and transport. It shows the energy system of Pecs in terms of hourly production and demand levels – and these values enable the model to analyse intermittent energy sources. The model is also validated – to ensure that it is satisfactory for the simulation of future energy systems. It analyses two scenarios – one where the city does not implement the changes proposed in the strategy, and one where it does. The paper compares the two scenarios based on sustainability, energy security and affordability.

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 Biomass materials are renewable sources that abundant worldwide due to natural plants and living organisms. Lignocellulosic biomass can be categorized as hardwood, softwood, agricultural wastes, and grasses. Agricultural residues those which of them have importance due to being produced in huge amounts in the worldwide annually. Food wastes and agricultural wastes are utilized either alternative use such as generating energy, fuels or disposal. However, disposal of these residues is follow out either scraping or burning way. This study aims to convert industrial agricultural origin biomass by using hydrothermal carbonization method to carbon-based material having high conductivity for use in supercapacitor production by using different activating chemicals. Hydrothermal carbonization was applied to different biomass samples such as nutshell, hazelnut shell, and corn cob. The elemental analysis of the obtained biochar was carried out and it was determined that the highest source of biomass was corn cob. The selected biochar has been chemically activated with different chemicals such as KOH, NaOH, H3PO4 and, ZnCl2. Advanced carbonization of activated biochar was carried out at 500, 600, 700 and 800 °C with 1, 1.5 and 2-h retention times. The resulting carbon-based products were mixed with KBr and identical pellets were prepared and their electrical conductivity values were measured. Electrical conductivity results, NaOH-800 °C-2h and ZnCl2-700 °C-1.5 h obtained from the process prepared from the biocidal pellets were determined to have the highest conductivity value. Brunauer–Emmett–Teller (BET) and Scanning Electron Microscope (SEM) analyses of the samples with the highest conductivity values were performed and surface morphologies were examined.

Diesel engines have proved its utility in transport, agriculture and power sector. Environmental norms and scared fossil fuel have attracted the attention to switch the energy demand to alternative energy source. Oil derived from Jatropha curcas plant has been considered as a sustainable substitute to diesel fuel. However, use of straight vegetable oil has encountered problem due to its high viscosity. The aim of present work is to reduce the viscosity of oil by heating from exhaust gases before fed to the engine, the study of effects of FIT (fuel inlet temperature) on engine performance and emissions using a dual fuel engine test rig with an appropriately designed shell and tube heat exchanger (with exhaust bypass arrangement). Heat exchanger was operated in such a way that it could give desired FIT. Results show that BTE (brake thermal efficiency) of engine was lower and BSEC (brake specific energy consumption) was higher when the engine was fueled with Jatropha oil as compared to diesel fuel. Increase in fuel inlet temperature resulted in increase of BTE and reduction in BSEC. Emissions of NO from Jatropha oil during the experimental range were lower than diesel fuel and it increases with increase in FIT. CO (carbon monoxide), HC (hydrocarbon), CO(2) (carbon dioxide) emissions from Jatropha oil were found higher than diesel fuel. However, with increase in FIT, a downward trend was observed. Thus, by using heat exchanger preheated Jatropha oil can be a good substitute fuel for diesel engine in the near future. Optimal fuel inlet temperature was found to be 80 degrees C considering the BTE, BSEC and gaseous emissions. (C) 2010 Elsevier Ltd. All rights reserved.

Abstract Recovery of waste heat in large industrial plants is nowadays an important topic of thermal optimization. In the present study, energy, exergy, and exergoeconomic analysis of an integrated system, Tehran's waste-to-energy power plant coupled with an organic Rankine cycle (ORC), is analyzed. Parametric study of essential parameters (moisture content, pinch point temperature differences of the HROG, steam generator's superheat temperature difference, and steam turbine inlet pressure) is performed thermodynamically. The best system performance achieved using R123 as the working fluid of ORC. After implementation of the waste-heat-recovery system into the WtE plant, with R123 the energy and exergy efficiencies increase from 17.27% to 19.51% and 14.49%–16.36%, respectively. Exergy analysis reveals that the gasifier and steam generator are the main source of exergy destruction in the overall system. Additionally, the results of single-objective optimization based on maximum exergy efficiency and minimum total product unit cost were calculated. Furthermore, multi-objective optimization based on genetic algorithm using MATLAB software is implemented to find the optimum point with respect to exergy efficiency and total product unit cost as the objective functions. The exergy efficiency and total product unit cost at the optimum point, considering multi-objective optimization, are 19.61% and 24.65 $/GJ, respectively.

Abstract Oxy-combustion with a circulating fluidized bed (Oxy-CFBC) can facilitate the separation of high CO2 concentration and reduce emissions by biomass co-firing. This study investigated Oxy-CFBC characteristics such as temperature, solid hold-up, flue gas concentrations including CO2, pollutant emissions (SO2, NO, and CO), combustion efficiency and ash properties (slagging, fouling index) with increasing input oxygen levels (21–29 vol%), and biomass co-firing ratios (50, 70, and 100 wt% with domestic wood pellet). The possibility of bio-energy carbon capture and storage for negative CO2 emission was also evaluated using a 0.1 MWth Oxy-CFBC test-rig. The results show that combustion stably achieved with at least 90 vol% CO2 in the flue gas. Compared to air-firing, oxy-firing (with 24 vol% oxygen) reduced pollutant emissions to 29.4% NO, 31.9% SO2 and 18.5% CO. Increasing the biomass co-firing from 50 to 100 wt% decreased the NO, SO2 and CO content from 19.2 mg/MJ to 16.1 mg/MJ, 92.8 mg/MJ to 25.0 mg/MJ, and 7.5 mg/MJ to 5.5 mg/MJ, respectively. In contrast to blends of sub-bituminous coal and lignite, negative CO2 emission (approximately −647 g/kWth) was predicted for oxy-combustion only biomass.

A simple framework for environmental life-cycle assessment (LCA) based on physical measures is presented and applied to the comparison of long-distance energy transport systems, including high-voltage alternating and direct current transmission lines, pipelines for gas and oil, inland waterway, road and rail transportation. Quantitative indicators for fossil-energy consumption, air-emission impacts, land use, audible noise impacts, and visual impacts are developed. These can be used in the context of existing planning or decision making instruments, such as integrated resource planning, technology assessment, LCA, regional planning, line and power plant siting. To reduce all information to a single indicator, the concept of the equivalent impacted area is introduced for land use, audible noise and visual impacts. It is shown that pipelines are the environmentally most favourable option in the case of oil and gas transport. In the case of coal transport, early conversion to electricity and transmission by high-voltage lines can lead to significant impact reductions compared to coal transport with barges and trains. For long transport distances, high-voltage direct current lines yield particularly good results.