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Researchers have been driven to investigate sustainable alternatives to cement production, such as geopolymers, due to the impact of global warming and climate change resulting from greenhouse gas emissions. Currently, they are exploring different methods and waste materials to enhance the mechanical and physical properties of geopolymer and expand its application range. This review paper offers a thorough analysis of the utilization of various waste materials in geopolymer manufacturing and shows the creative contribution of this research to the development of environmentally friendly cement substitutes. The article covers the properties, durability, and practical applications of geopolymer composites made from various waste binders. It includes a microstructure and chemical analysis. The research findings indicate that geopolymers are an effective cementitious binder substitute for cement in various applications. Additionally, the ecological and carbon footprint analysis highlights the sustainability of geopolymers compared to cement.

Abstract In this work, we investigate novel solid–solid phase-change cascade systems based on mixtures of lithium and sodium sulfates. Solid–solid phase-change materials (PCMs) can be coupled with concentrated solar power technologies. They present several advantages over solid–liquid PCMs including lower thermal expansion, lower or no corrosiveness, and no need for encapsulation. In solid–solid PCMs, the energy is stored during crystal structure transitions. Specifically, lithium sulfate undergoes a crystal structure transition (monoclinic to cubic) at 576 °C, which is a suitable temperature for concentrated solar thermal technologies. Due to the high cost of lithium sulfate, we evaluated the potential of mixing lithium with sodium sulfate to create solid–solid cascaded PCM systems to provide higher thermal storage densities. We used differential scanning calorimetry, high-temperature in situ X-ray diffraction and thermogravimetric analysis to evaluate the phase-transition temperature, phase-change enthalpy, specific heat capacity, crystalline phase composition and thermal expansion. The obtained values for heat capacity and enthalpies of phase transitions showed good agreement with available thermodynamic databases. Therefore, further calculations of thermodynamic properties of each mixture in the system were performed for designing cascaded latent thermal energy storage system. From the PCM mixtures studied, NaLiSO4 shows the greatest stability under ambient conditions. A mixture of 59.17% NaLiSO4 and 40.83% Li2SO4 allows an optimum charge of both PCMs for power cycles such as supercritical CO2. Economic assessment revealed that this cascade system has an estimated cost of $50.2 kWhth−1.

Abstract South Asia is the home of over 1.6 billion people. The countries in the region are aspiring to become fully developed nations by the middle of this century. Rapid industrialization and attainment of sustainable development goals (SDGs) are important requirement to achieve this goal. South Asian nations thus need secured energy and power generation, distribution and supply. Currently the entire South Asian region is energy deficient. Hence achieving energy security and adequate generation of power pose a major challenge. However, regional and sub-regional collaboration in energy and power can enhance energy security if indigenous energy resources are collectively utilized by the member countries. The recently established Indian Energy Exchange (IEX) aims to facilitate in-country and cross-border power and energy trading. Both power producers and buyers can bid live through the IEX platform. This paper reviews some features of IEX and Australian Energy Market Operator (AEMO) in order to understand the operating mechanism of such energy and power trading platforms.

Abstract Thermal conductivity of bricks is an important parameter as it directly influences the heat losses from buildings and thus increases the energy consumption. The main focus of this study was to develop thermally efficient burnt clay bricks incorporating agricultural wastes on industrial scale. For this purpose, agricultural wastes (sugarcane bagasse ash (SBA) and rice husk ash (RHA)) were acquired from a sugar industry and a brick kiln. Burnt clay bricks were manufactured in an industrial kiln by incorporating SBA and RHA in various dosages (i.e. 5%, 10% and 15%) by clay weight. Physico-mechanical and thermal properties of brick specimens incorporating agricultural wastes were studied. It was observed that lighter weight bricks can be produced using agricultural wastes, which are helpful in reducing both the cost and overall weight of the structure. Addition of agricultural wastes in burnt clay bricks resulted into reduced compressive strength. However, brick specimens incorporating SBA and RHA up to 15% satisfied the minimum requirement for compressive strength according to different standards for masonry construction. Increase in apparent porosity with decrease in thermal conductivity was also observed with increasing content of SBA and RHA in burnt clay bricks. Substitution of clay by 15% SBA and RHA in the production of burnt clay bricks reduced the thermal conductivity by 31% and 29%, respectively. Microscopic images also showed the presence of interconnected and irregular shaped open pores after addition of agricultural wastes in burnt clay bricks. Based on this study, it can be concluded that the utilization of SBA and RHA (up to 15% by clay weight) in manufacturing of burnt clay bricks is not only helpful in landfill reduction but also leads towards the development of sustainable and thermally efficient construction material.

There has been an increasing focus on using Building Information Modelling (BIM) for sustainability assessment. Especially in the aspect of applying BIM-based tools to provide documentation for Green Building Certification Systems (GBCS) credits in sustainability assessment. Despite the huge potential of BIM for GBCS, there is limited literature that has established this link. Hence, the purpose of this paper is to explore the synergies between BIM and GBCS to achieve a deeper understanding of the GBCS currently BIM-enabled, level of BIM implementation in GBCS sustainability areas, challenges and gaps in integrating BIM and GBCS, BIM and GB tools currently in use and areas for further research in the BIM-GBCS domain. The research methodology includes a combination of systematic literature review (SLR) and gap spotting. The SLR includes a total of 84 papers from highly ranked journals between 2009 and 2020. In terms of sustainability areas, energy (71%) has the highest amount of literature in the environmental sustainability dimension while social and economic dimensions had a representation of 15% and 11%, respectively. The knowledge gaps and areas for proposed future research directions are critical to developing work in the BIM-GBCS domain. Refereed/Peer-reviewed

Abstract For design and simulation of solar energy systems, quality information about all components of solar irradiance is crucial. In cases when only global irradiance measurements are available, separation models are a useful method to estimate DNI and diffuse irradiation. Several of such models have been developed since the 1960s, most of them aiming to deliver estimates in hourly resolution. For higher data resolution, such as in minute data, those models are not able to describe fast transient and cloud enhancement phenomena commonly observed in data with smaller time-steps. This paper proposes an adaptation of the BRL separation model, making it capable of delivering more precise irradiance estimates for higher resolution data. Two models result from this adaptation: one for Brazil and other for Australia. The proposed models yield a more precise DNI and diffuse fraction estimates to their respective countries, compared to other separation models commonly used in the technical literature. For example, using the recommended Combined Performance Index (CPI) as a single statistical indicator, the proposed model yields DNI estimates with CPI from 230 to 350% for Australia, and from 270 to 800% for Brazil, while the Engerer model, recently recommended as a ‘‘quasi-universal” 1-min separation model, yields DNI estimates with CPI from 500 to 700% for Australia, and from 600 to 1800% for Brazil.

It is usually uneconomic to provide mains power to small remote communities even when high voltage lines pass by a village. Local authorities normally resort to diesel-powered generators which require expensive fuel which is difficult to bring into remote areas. Furthermore they are noisy and require frequent maintenance which is often neglected in remote areas due to limited resources and know-how. Neither wind nor sun provides reliable power in humid tropical regions where there is a lot of still and overcast weather. Towers are found to attract lightning strikes which can destroy electronic controls, fungus grows on solar panels, and the multiple electrical connections on photovoltaic arrays corrode away in hot, humid climates. Micro hydro is an attractive option in mountainous areas, and a 30 kW high head and a 3 kW low head plant have been built, using village labour and surplus and discarded materials. Both are operating satisfactorily. However conventional micro hydro is not possible in flat country where there is little elevation, and work is now in progress to evaluate suitable hydrokinetic turbines on rivers in the humid tropics. Numerous companies around the world are now developing hydrokinetic turbines to harvest tidal and river flows, but a major problem with most designs is clogging by floating debris, especially in tropical rivers.

Abstract Current definitions of energy poverty oversimplify the fluid and dynamic nature of the lived experiences of the energy impoverished. By drawing on empirical observations in the aftermath of Nepal’s humanitarian crises in 2015, we showcase the vulnerability of vital energy systems that threatens human security and negatively impacts on the lives and livelihoods of those affected. In search of greater human security, we observed a reverse energy transition whereby people abandoned modern fuels and returned to biomass-based traditional cooking practices. These observations in Nepal suggest that people respond and adapt to energy insecurity with strategies that move them in and out of energy impoverishment in a much more fluid process than many of the contemporary statistics and known indicators imply. After presenting the case in Nepal, we invoke several questions that challenge conventional ways of conceptualising, identifying and defining energy poverty and present a research agenda for strengthening scholarship in this field.

Abstract The energy for the solvent regeneration of post-combustion carbon capture (PCC) process is typically provided by steam bleeding from the power plant (PP) steam cycle. The energy penalty for steam bleeding results in serious reduction in the PP capacity estimated to be in the range of 10–40%. Power plant repowering or hybridization using solar-assisted PCC (SPCC) is a promising approach to satisfy carbon capture targets as well as PP load, concurrently. The drawback of this methodology is that notable amounts of solar energy are wasted during heat transfer from solar radiation to rich solvent. This paper presents a novel approach by eliminating the costly desorber system and using solar collector pipe (i.e. parabolic trough pipe) to directly heat the rich solvent and disassociate the bonds of CO2-solvent. This novel technology lowers the process capital expenditure, and also reduces the solvent regeneration energy bringing it close to its theoretical values. The elimination of the complex desorber column also increases the flexibility of the PP operation in response for market dynamics. A case-study for Sydney-Australia shows that in comparison with SPCC methodology, this state-of-the-art approach could notably improve the economics of the process and reduce the size of solar collector field (SCF).