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Electricity generation systems have traditionally been evaluated using only a limited number of economic or environmental indicators, for example capital investment, generation cost or carbon dioxide emissions. Moreover, the evaluations have generally been restricted to performance within the geographic boundary of the power station. This paper reports a sustainability assessment of power generation from Australian fossil fuels, notably black coal, brown coal and natural gas. A range of key sustainability indicators incorporating environmental, economic and social performance are included. The system boundary incorporates fuel extraction, fuel transport to the power station, generation of power, and transmission of electricity to the point of use. Most commonly employed existing technologies and some promising advanced technologies for power generation are considered. The cases of exporting Australian LNG and black coal to Japan for power generation in that country have also been considered. No one fuel or technology system was superior or inferior for every indicator. However the following generalizations can be made: Natural gas combined cycle systems have advantages for the majority of environmental and economic indicators, brown coal has an advantage in terms of value added, and black coal has relatively poor safety performance.

Abstract In recent years, modern appliances with high electricity demand have played a significant role in residential energy consumption. Despite the positive impact of these appliances on the quality of life, they suffer from major drawbacks, such as serious environmental concerns and high electricity bills. This paper introduces a consolidated framework of load management to alleviate those drawbacks. Initially, benefiting from a demonstrative analysis of home energy consumption data, controllable and responsive appliances in smart home are identified. Then, the energy consumption pattern is reduced and shifted using flexible load models and better utilization of existing energy storage systems. This can be achieved through data mining approaches, i.e., density-based spatial clustering of application with noise (DBSCAN) method. In this technique, no sensor for detection or measurement instruments will be required, whose deployment incur cost to the system or increase security risk for consumers. In the following, one scheduling of using controllable appliances, which is formulated by convex optimization, is considered for the demand response (DR) program, provided that this plan doesn't affect customers’ priority and convenience. In the last stage, the deployment of energy storage systems, such as plug-in hybrid electric vehicles (PHEVs) and battery energy storage systems (BESS), is introduced to lower the energy cost and improve the performance of the proposed DR model. Simulation results of this demand response are compared with conventional k-clustering methods to confirm the economic superiority of the DBSCAN clustering technique using the data of a residential unit during three different scenarios.

A better understanding of the stress–strain behaviors of shale samples after shale-CO2 or shale-water–CO2 interactions is of great importance to CO2 enhanced shale gas exploitation and CO2 sequestrating in shale reservoirs. In this study, a constitutive model that combines with the modified Duncan–Chang model and Weibull distribution-based model is applied to investigate the stress–strain characteristics of low-clay shale samples treated by sub-/super-critical CO2 and sub-/super-critical CO2 + water for different times (10 days, 20 days, and 30 days). The results show that the model could describe well the crack closure stage, the elastic stage, and the inelastic stage of shale samples. The axial strain at the connection point between the two models varies from 28.51 to 43.36% of the axial strain at the failure point. Shale-CO2 or shale-water–CO2 interactions make shale samples more ductile at the crack closure stage, which can be depicted as the increase of initial elastic modulus during the imbibition process. The brittleness index values (BI) which are calculated based on the combined constitutive model increase with increasing soaking time for shale samples treated by sub-/super-critical CO2, and decrease with increasing soaking time for shale samples treated by sub-/super-critical CO2 + water.

The design and assessment of net-zero buildings commonly focus exclusively on the operational phase, ignoring the embodied environmental impacts over the building life cycle. An analysis is presented on the consequences of integrating embodied impacts into the assessment of the environmental advantageousness of net-zero concepts. Fundamental issues needing consideration in the design process - based on the evaluation of primary energy use and related greenhouse gas emissions - are examined by comparing three net-zero building design and assessment cases: (1) no embodied impacts included, net balance limited to the operation stage only; (2) embodied impacts included but evaluated separately from the operation stage; and (3) embodied impacts included with the operation stage in a life cycle approach. A review of recent developments in research, standardization activities and design practice and the presentation of a case study of a residential building in Norway highlight the critical importance of performance indicator definitions and system boundaries. A practical checklist is presented to guide the process of incorporating embodied impacts across the building life cycle phases in net-zero design. Its implications are considered on overall environmental impact assessment of buildings. Research and development challenges, as well as recommendations for designers and other stakeholders, are identified.

The concept of resilience is a crucial part in crafting visions of desirable futures designed to withstand the widest variety of external shocks to the system. Backcasting scenarios are widely used to envision desirable futures with a discontinuous change from the present in mind. However, less effort has been devoted to developing theoretical frameworks and methods for building backcasting scenarios with a particular focus on resilience, although resilience has been explored in related sustainability fields. This paper proposes a method that helps design backcasting scenarios for resilient futures. A characteristic of the method is to delineate “collapse” futures, based upon which resilient futures are described to avoid the various collapsed states. In the process of designing backcasting scenarios, fault tree analysis (FTA) is used to support the generation of various risk factors and countermeasures to improve resilience. In order to test the effectiveness of the proposed method, we provide a case study to describe resilient energy systems for a Japanese community to 2030. Four expert workshops involving researchers from different disciplines were organized to generate diversified ideas on resilient energy systems. The results show that three scenarios of collapsed energy systems were described, in which policy options to be taken toward achieving resilient energy systems were derived.

CuInSe2 thin films were cathodically electrodeposited on conducting substrates from aqueous solutions containing CuCl, InCl3 and SeO2. Structural characterization were carried out by microprobe, X-ray diffraction and electron microscopy studies. The presence of chalcopyrite phase CuInSe2 was confirmed from X-ray studies. Optical absorption studies indicated band gap values of about 1.1 eV. Electrical characterization was carried out by Hall effect and resistivity studies. The room temperature resistivity and mobility were found to be 2.15×10−3 ω cm and 8.1 cm2 V−1s−1 respectively for p-type films. Diffusion of In into p-type films converted them to n-type. Photovoltaic and photoelectrochemical solar cells were fabricated with Mo/p-CuInSe2/CdS/Au and Mo/n-CuInSe2/I1−I3−/C configurations. The open circuit photovoltage and short circuit current densities were 188 mV and 0.056 mA cm−2 for photovoltaic cells and 172 mV and 2.75 mA cm−2 for photoelectrochemical cells under 100 mW cm−2 intensity of illumination, without optimisation.

Abstract Temperature and performance modeling of thermoelectric generators (TEGs) have long been discussed. However, due to the high nonlinearity of heat conduction in thermoelectric (TE) materials, the analytical model of TEGs is difficult to develop and there is no such model exists at this time. In this paper, we revisit the problem and develop an analytical model to evaluate the performances of a TEG. The model considers contact resistance between TE leg and electrode, and temperature dependent TE material properties. Through the analytical model, we give simplified expressions to calculate the leg temperature profile, energy conversion efficiency, and output power for a single TE leg pair. These expressions are validated by either experiment or finite element (FE) simulation. The results show that an optimal cross-section area exists for maximum efficiency. The optimal leg length decreases as the thermal contact conductance increases while the optimal leg length has no relation with electrical contact resistance. Based on the results of this paper, we provide some useful suggestions for the design of high-performance thermoelectric generators.

Abstract This study sheds new light on the variability of wind power across the Australian NEM (National Electricity Market) and in doing so gives an insight on the potential network configuration for a high RE (Renewable Electricity) future. We present idealised cost-minimised simulations for the NEM utilising onshore wind, large-scale solar, pumped hydro and OCGT (open cycle gas turbines) technologies. A model using gridded meteorological data from the regional ACCESS-R (Australian Community Climate and Earth-System Simulator) simulates wind and solar technology output along with generation from OCGT to meet demand in the NEM for the period 2010–2011. A cost for connecting each location to the nearest major load centre is introduced and a base scenario created from an initial connection cost of $1 M/km. A sensitivity study reveals that a cost of $8 M/km results in the contraction of all renewable resources to four major wind installations. Compared to the base scenario the four major wind locations share much of the variability in renewable energy output, demonstrating that the NEM region has four distinct wind regimes. Separated by 1,400 km these four wind installations provide an optimisation-based decorrelation length for the NEM. This information is particularly useful for long-term planners of large-scale energy infrastructure.

A mechanistic study is detailed in which coal ash is heated with its shrinkage measured continuously up to a temperature of 1600°C. The temperatures corresponding to the rapid rate of shrinkage correspond to the formation of eutectics identified on phase diagrams. Samples were therefore heated to these temperatures, cooled rapidly and examined using a scanning electron microscope (SEM) to identify the associated chemical and physical changes. The progressive changes in the range of chemical composition (from SEM), the extent of undissolved ash particles and porosity were then quantified and related to homogenisation, viscosity and ash fusion mechanisms. Alternate ash fusion temperatures based on different levels of shrinkage have also been suggested to characterise the ash deposition tendency of the coals.