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Water and electricity have a unique relationship in the modern world as one requires the other in a complex system of networks to supply the utility to the customers. This energy–water interaction is especially peculiar in the Gulf Cooperation Council, where there are limited water resources, but extremely high use rates. Qatar provides a unique case in terms of extreme water scarcity and excessive water use. To understand the intricate network, this paper establishes an updated and comprehensive qualitative model of the water system in the country with the help of a water balance and system dynamics (causal loop diagram) methodology. Regression estimates are then used to estimate future water and energy consumption in addition to carbon dioxide emissions until the year 2050. Finally, system dynamics (stock and flow diagram) is used to determine the supply impacts of efficiency policies including limiting of groundwater abstraction to only 50 million m3, reduction of water consumption in the household, commercial and industrial sector by 10%, and gradual increase in the share of reverse osmosis (RO)-produced desalinated water to 50% in order to assess the supply volume, electricity consumption and CO2 emissions. The efficient use of water in different sectors of the economy results in a combined saving of 1222 GWh (8.1%) or 594,000 tons CO2. Furthermore, by moving to membrane-based desalination technology energy consumption and carbon dioxide emissions can be reduced by 3672 GWh (24.3%) and 1.8 million tons CO2, respectively. Further results suggest that while replacing groundwater with desalinated water can increase the energy consumption significantly, reuse of treated wastewater has almost the same footprint as groundwater, but can increase the resilience of the system considerably as groundwater abstraction levels are lowered to their renewal rates.

Currently, there is a widespread interest in the different methods of chemical enhanced oil recovery (EOR) as a result of the continuous decline in the conventional oil reserves and the accelerated increase in the global energy demand. Surfactant flooding is a well-established method of chemical EOR. This method has proven successful as it increases oil recovery through a combination of mechanisms. These include interfacial tension (IFT) reduction, wettability alteration, foam generation and emulsification. Despite its popularity, surfactant flooding is still challenged by issues including instability under harsh (or normal) reservoir conditions and excessive adsorption. These issues affect the expected oil recovery and thereby reduce the economic returns of EOR projects. Nevertheless, surfactants can be properly selected according to reservoir conditions and rock type. This is usually carried out using surfactant screening methods, which impose limits related to the IFT, surfactant adsorption and other factors under given temperature and salinity conditions. This paper reviews surfactant characterization and phase behavior, the role of surfactants in oil recovery, surfactant adsorption onto reservoir rock, and the application of surfactants in EOR on both laboratory and field scales. Finally, the review presents current research trends and future prospects based on recently published studies in the area of surfactant flooding.

Ammonia has been proposed as a replacement for fossil fuels. Like hydrogen, emissions from the combustion of ammonia are carbon-free. Unlike hydrogen, ammonia is more energy dense, less explosive, and there exists extensive experience in its distribution. However, ammonia has a low flame speed and combustion emits nitrogen oxides. Ammonia is produced via the Haber-Bosch process which consumes large amounts of fossil fuels and requires high temperatures and pressures. A life cycle assessment to determine potential environmental advantages and disadvantages of using ammonia is necessary. In this work, emissions data from experiments with generating heat from tangential swirl burners using ammonia cofired with methane employing currently available technologies were utilized to estimate the environmental impacts that may be expected. Seven ammonia sources were combined with two methane sources to create 14 scenarios. The impacts from these 14 scenarios were compared to those expected from using pure methane. The results show that using ammonia from present-day commercial production methods will result in worse global warming potentials than using methane to generate the same amount of heat. Only two scenarios, methane from biogas combined with ammonia from hydrogen from electricity and nuclear power via electrolysis and subsequent ammonia synthesis using nitrogen from the air, showed reductions in global warming potential. Subsequent analysis of other environmental impacts for these two scenarios showed potentially lower impacts for respiratory organics, terrestrial acidification-nutrification and aquatic acidification depending on how the burner is operated. The other eight environmental impacts were worse than the methane scenario because of activities intrinsic to the generation of electricity via wind power and nuclear fission. The results show that generating heat from a tangential swirl burner using ammonia currently available technologies will not necessarily result in improved environmental benefits in all categories. Improvements in renewable energy technologies could change these results positively. Other means of producing ammonia and improved means of converting ammonia to energy must continue to be explored.

This paper aims at the sustainable development of activated carbons for value-added applications from the waste tyre pyrolysis product, tyre char, in order to make pyrolysis economically favorable. Two activation process parameters, activation temperature (900, 925, 950 and 975 °C) and residence time (2, 4 and 6 h) with steam as the activating agent have been investigated. The textural properties of the produced tyre char activated carbons have been characterized by nitrogen adsorption-desorption experiments at -196 °C. The activation process has resulted in the production of mesoporous activated carbons confirmed by the existence of hysteresis loops in the N2 adsorption-desorption curves and the pore size distribution curves obtained from BJH method. The BET surface area, total pore volume and mesopore volume of the activated carbons from tyre char have been improved to 732 m(2)/g, 0.91 cm(3)/g and 0.89 cm(3)/g, respectively. It has been observed that the BET surface area, mesopore volume and total pore volume increased linearly with burnoff during activation in the range of experimental parameters studied. Thus, yield-normalized surface area, defined as the surface area of the activated carbon per gram of the precursor, has been introduced to optimize the activation conditions. Accordingly, the optimized activation conditions have been demonstrated as an activation temperature of 975 °C and an activation time of 4 h.

Besides being limited in quantity, conventional energy sources also emit toxic gases. The Photovoltaic (PV) Solar System is one of the most energizing green energy sources. Around the globe, solar panels are being installed on barren land as well as on the roofs of buildings to generate electricity. An education institute in northern India recently took a step in this direction by installing a grid-tied 100 kWp solar power plant. The installed PV panels are tilted at an angle of 30° and mounted on the roof of the building. The actual PV plant system’s performance differs from the performance under laboratory conditions. Hence, performance evaluation of real outdoor plants becomes essential, especially when the plant is commissioned in different situations, such as roof-mounted systems. Many softwares can estimate the plant’s performance evaluation, but their reliability is not yet proven. This paper examines the performance evaluation of grid-tied PV plants between January 2019 and December 2019 in accordance with the IEC 61724 standard. Moreover, the results of the actual plant have also been compared with the results from the PV*Syst software that simulates the real-time behavior of the plant. Further, in order to evaluate the power plant’s performance, this paper analyzes the various parameters of the PV plant, including reference yield, final yield, and performance ratio of the PV plant. An evaluation of the module’s performance indicates that it has produced 101.57 MWh of energy over 1 year, with a performance ratio of 0.60. It is evident from the comparative analysis that rooftop solar panels are an economically viable and technologically feasible means of providing electricity in the northern parts of India. By taking such measures, the institutes or offices can protect the environment and save money by becoming microgrids. The proposed project provides a roadmap for installing rooftop photovoltaic plants in populated cities without occupying additional land.

Construction and Demolition Waste (CDW)-based geopolymers are expected to lower the construction sector’s environmental impacts by reducing the use of ordinary cement and reusing waste materials and are considered a substantial step toward a circular economy and environmental sustainability in the long run. However, due to the energy-intensive mechanical, thermal, and chemical processes involved in preparing the CDW-based geopolymers, it is essential to quantify their environmental implications in the early stages of development. The objective of the study is to analyze the environmental sustainability of newly developed geopolymers containing CDWs, i.e., roof tile (RT), hollow brick (HB), red clay brick (RCB), and glass waste (G) based geopolymer binder materials. The study aims to identify the environmental impact of their critical process parameters using Life Cycle Assessment (LCA) approach and evaluate their production feasibility at a location with completely different energy and water scenarios. According to the results of the study, compared to Ordinary Portland Cement (OPC), all the CDW-based geopolymers had lower environmental impacts. G-based geopolymer binder resulted in the lowest Global Warming Potential (GWP) with a 38% reduction, followed by RT and HB with 35.3% and 34.8%, respectively. However, due to the energy-intensive processes of crushing and grinding CDWs, electrical energy is identified as a hotspot with significant environmental impacts. The replacement of mix-grid energy with hydropower reduced GWP by 63.3%, Eutrophication (EP) by 52.5%, Acidification potential (AP) by 86.4%, and fossil fuel deposition (FFD) by 74%. The highest environmental performance is calculated for electricity produced from hydropower, wind, and photovoltaics, then geothermal and biomass resources.

Abstract A precise estimate of PV panels temperature is crucial for accurately assessing their electrical performance. Therefore, in this study, one of the main aims has been to significantly improve the prediction accuracy of the PV cell temperature, by using realistic boundary conditions. Unlike previous thermal models in the literature, which usually focus on its mere application, a detailed step by step development and numerical implementation of the complete model has also been provided in great details in this work. The developed model is transient, so it can fully simulate the thermal performance of any PV panel under time-varying field conditions. Once the model is defined for a specific PV panel, the only external inputs it needs are the total incident solar irradiation, wind speed and the ambient temperature. The model has been adequately validated through PV panel’s datasheet provided information, literature data and against a versatile set of experimental data under various weather conditions. After thorough validations, the developed model was compared to various other widely used empirical, analytical and numerical thermal models from the literature. The comparison shows that by using realistic boundary conditions, the developed thermal model has far better prediction accuracy than other models from the literature. The methodology presented in this study is completely generic. That is, though it has been implemented and validated here for a silicon-based PV module the approach may be used to model any free-standing plane PV surface, with appropriate modifications to layer thicknesses and material properties. A range of weather conditions may also be accommodated.

Abstract The increased demand of energy in domestic applications necessitates the development of innovative engineering solutions in building heating, ventilating, and air conditioning (HVAC) systems. As the largest energy intensive sector is domestic buildings, more focus is currently directed to reduce air conditioning energy consumption. Double-pipe heat exchangers are considered one of the practical solutions in today’s HVAC industry. Nevertheless, a few studies focus on using double-pipe heat exchangers in air conditioning applications. This paper experimentally investigates the usage of double-pipe condenser and evaporator in an air conditioning system serving a 45 m 3 balanced calorimeter of 2.24 kW heat load. Deionized water (DIW) was used as the secondary heat transfer working fluid for both the evaporator and condenser units, and R-22 was used as the AC system refrigerant. Experimental results of the double-pipe heat evaporator/condenser setup showed a promising reduction in the compressor work and an increase in the system coefficient of performance (COP). The collected data showed that the system efficiency depends more on the evaporator DIW flowrate than on the condenser DIW flowrate. By increasing the DIW flowrate in the evaporator, the compressor work was shown to decrease, while the COP was shown to increase. In comparison with a standard rated air conditioning unit, using a double-pipe evaporator and condenser units with the maximum DIW flowrates resulted in a decrease of about 53% in the compressor work and a similar percentage of increase in the system COP.