Abstract

The cost of unsubsidized electricity in off-grid areas, particularly in the islands dependent on fossil fuels, is expensive. Previous studies and recent installations have proven that renewable energy-based hybrid systems could be suitable alternative to diesel power plants in island grids. In this comprehensive analysis of small island grids in the Philippines, results show that there is a huge economic potential to shift the diesel generation to solar photovoltaics-battery-diesel hybrid systems, with an average cost reduction of around 20% of the levelized cost of electricity. By encouraging private sector participation, hybridization could help provide electrification for twenty-four hours, stabilize the true cost of generation rate with less dependence on imported diesel prices, and reduce greenhouse gas emissions. Further, the declining cost of solar modules and batteries will significantly improve the economics of energy transition in the island grids.

Abstract

Recent major droughts in Brazil have given rise to discussions about water availability and security in relation to energy production. The relationship of the two resources, the water-energy nexus, is recognised as being of importance in literature and metrics for its estimation and understanding are sought after. One important aspect in understanding the water-energy nexus of hydroelectricity is estimating its water consumption and also its water footprint. In order to do this, this study uses a modified Penman-Monteith method to estimate evaporation from Brazil’s reservoirs for the period 2010-2016 and subsequently calculates the water footprint of hydroelectricity reservoirs. The results show the evaporation variation in space and time in the reservoirs and the differences of water consumed per unit of energy in Brazil. The discussion provides insight as to how the results can be valuable for future management and planning purposes.

Abstract

In this paper, the energy performance of a flat-plate collector and a heat pipe evacuated tube collector exploited for domestic hot water production in the Mediterranean climate is compared. For this purpose, yearly data obtained from two field-trial solar water
heating systems are used. The selected systems are with forced circulation and installed near each other. The studied solar collectors are installed on the roof with the same slope angle of 45° and the surface azimuthal angle of 10°. The installed surface area of the
flat-plate solar collector is 4.41 m2, whereas for the heat pipe evacuated tube collector is 1.5 m2. The annual irradiation on solar collector plane was 1,456 kWh/m2year. Obtained results showed that the annual solar yield for the flat-plate collector was 664 kWh/m2year, whereas for the heat pipe evacuated tube collector was 885 kWh/m2year. The annual average collector efficiencies were 0.494 and 0.62, respectively.

Abstract

In this paper the detailed theoretical investigation on absorption of carbon dioxide, from flue gas in coal based thermal power plants has been presented. For absorption studies, monoethanolamine solution is considered as a solvent. The mathematical model for the absorption column has been developed by considering thin film model approach. Unified method is used for an overall estimation of carbon dioxide absorption. The carbon dioxide concentration profile at a given stage, using the thin film layer model, has been predicted at 298 K and 318 K. From the results it is noted that carbon dioxide concentration decreases from interface concentration at equilibrium to a minimum of 0 kmol/m³ up to a distance of ±2 micrometers. Overall estimation of carbon dioxide absorption has been carried out using the unified model approach. The total amount of carbon dioxide absorbed in absorption column is estimated to be 95.60% of the inlet carbon dioxide with 30 trays, L/G ratio of 8.5 and carbon dioxide flow rate of
95.74 kmol/m³. The results revealed that reactive absorption is very effective in absorbing carbon dioxide into monoethanolamine solvent.

Abstract

This work deals with the potential application of artificial neural networks to model sunshine duration in three cities in Algeria using ten input parameters. These latter are: year and month, longitude, latitude and altitude of the site, minimum, mean and maximum air temperature, wind speed and relative humidity. They were selected according to their availability in meteorological stations and based on the fact that they are considered as the most used parameters by researchers to model sunshine duration using artificial neural networks. Several network architectures were tested to choose the most accurate and simple scheme. The optimum number of layers and neurons was determined by trial and error method. The optimized network was obtained using Levenberg-Marquardt back-propagation algorithm, one hidden layer including 25 neurons with Tan-sigmoid transfer function. The model developed in this study has the ability to estimate sunshine duration with a mean absolute percentage error value equals to 2.015%, a percentage root mean square error of 2.741% and a determination coefficient of 0.9993 during test stage.

Abstract

Increasing urbanization and the effects of climate change will bring new challenges for cities, such as energy saving and supply of renewable energy, preventing urban heat islands and water retention to deal with more frequent downpours. A major urban surface, the surface of roofs, is nowadays hardly exploited and could be used to make cities more ‘future proof’ or resilient. Many Dutch municipalities have become aware that the use of green roofs as opposed to bituminous roofs positively contributes to these challenges and are stimulating building-owners to retrofit their building with green roofs. This study aims at comparing costs and benefits of roof types, focused on green roofs (intensive and extensive) both on building- and city scale. Core question is the balance between costs and benefits for both scales, given varying local conditions. Which policy measures might be needed in the future in order to apply green roofs strategically in regard to local demands? To answer this question the balance of costs and benefits of green roofs is divided into a public and an individual part. Both balances use a strengths, weaknesses, opportunities and threats framework to determine the chance of success for the application of green roofs, considering that the balance for green roofs on an individual scale influences the balance on a public scale. The outcome of this combined analyses in the conclusion verifies that a responsible policy and a local approach towards green roofs is necessary to prepare the city sufficiently for future climate changes.

Abstract

In subtropical Hong Kong, clear glass is normally used as the translucent material for external windows of residential buildings, but it has poor heat insulation performance especially the tremendous solar heat gain in summer. To improve the thermal performance of conventional clear glass, a new heat blocking coating was developed. The coating can effectively absorb the near infrared radiation, so it can reduce the solar heat gain and therefore the energy use from air-conditioning systems. In this paper, the preparation of the heat blocking coating was firstly introduced. Then the optical and thermal properties of different types of window glazing were tested in the laboratory. Based on the experimental data, a combined daylight, thermal environment and building energy numerical model of a public rental housing was established to fully simulate the performance of different types of windows glazing. The results indicated that the heat blocking coating can reduce about 275.4 kWh (14.4%) electricity use per year compared to conventional clear window.

Abstract

The increasing issue of water quality degradation has affected the availability of water. The consideration of water quality is becoming more important for water minimisation. There is a need to integrate water quality into the current water assessment framework. This study tries to involve the water quality into the widely used water footprint assessment framework in order to quantify the water usability changes during the water use process. Based on water footprint concepts from international standard ISO 14046, water availability is further interpreted to emphasize the impact of water quality on the usability. An effective water availability footprint is defined as the quantitative and qualitative extent of a certain body of water which meets the needs of a certain purpose of water use. A water quality index is proposed to quantify the contribution of water quality on water availability, and two approaches of calculating water quality index are discussed, in order to explore the possibility of involving water quality into the water availability footprint assessment. Based on the definitions and framework, a case study is conducted to illustrate the features of this framework, and 3 outflows with different water quality are set to discuss the impact of different water quality profiles on the calculation of water availability footprint. It shows that water quality profiles can have a remarkable influence on the calculation. For the case with an outflow of F_2-1, the water availability footprints with minimum water quality index, average water quality index and the volumetric water footprints as 1,600 m³, 1,277 m³, and 1,000 m³. This indicator can determine the consumptive water use and also quantify the exploitation of water quality. The involvement of water quality regarding multiple contaminants in water footprint assessment should be further investigated in future studies.

Abstract

A highly complex microbial community involved in anaerobic sludge digesters plays vital roles in sludge treatment. The data on microbial ecology is important to accomplish efficient operation of the anaerobic digesters. This study is aimed at monitoring the bacterial community of three full-scale anaerobic digesters of a full-scale municipal wastewater treatment Plant in Dubai, United Arab Emirates. Fluorescent in-situ hybridization technique was applied to identify the bacterial groups and quantitative polymerase chain reaction to compare the richness of bacterial and archaeal domain. Results of the fluorescent in-situ hybridization technique analysis showed that the phylum proteobacteriawas most abundant followed by cytophage-Flavobacterium group of Bacteroides, Firmicutes and Actinobacteria. Among proteobacterial subclass Delta- and Alpha- were dominating than Gamma- and Beta-proteobacteria. The genus Desulfobacter and Desulfobacterium were the dominant groups hybridizing 70-76% of total 4’, 6’‒ diamidino – 2 phenylindole stained cells. The quantitative polymerase chain reaction results showed that Bacterial domain was dominating in all three digesters compared to the Archaeal domain.

Abstract

This paper proposes a simple mathematical model forupstream fish migration along rivers. The model describes the fish migration along a river based on a mixed optimal control approach having swimming velocity, school size, and stopping time of migration as control variables. The optimization problem reduces to a variational inequality. Its explicit “viscosity” solution is presented with the dependence of the fish migration on river environment. To prove uniqueness of the solution to the variational inequality requires a constructive argument not based on the conventional theorems. A novel finite difference scheme for solving the variational inequality is also proposed with its convergence results. An application example of the model discusses the upstream migration of Plecoglossus altivelis (Ayu) in Japan, which evaluates the dependence of the fish migration on the habitat quality and provides recommendations for managing river environment. This is an interdisciplinary research between environmental and mathematical fields.

Abstract

This work aims to investigate the application of a comprehensive nonlinear model-based predictive control strategy as a means to avoid unsafe or inappropriate operation of a gas turbine. Herein, the nonlinear model-based predictive control is employed to control compressor speed by varying the fuel flow in the combustion chamber. The methodology complies with the gas turbine constraints explicitly in the optimization procedure and, therefore, the nonlinear model-based predictive control algorithm ensures that process constraints are not violated. The nonlinear dynamic behaviour of the gas turbine is modelled with the aid of a first principle process simulator, which solves the equations of state and the conservation equations of mass, energy and momentum. The optimization procedure is achieved through the implementation of an evolutionary algorithm. Three scenarios are simulated: fuel consumption optimization, load removal/addition and load rejection. The proposed control strategy is successfully applied to both transient and steady-state operational modes of the gas turbine.

Abstract

This paper represents a development process of the energy concept maps in higher education learning environment, in order to foster new and innovative learning experiences as well as improve the understanding of energy planning, especially from the interdisciplinary perspectives, including energy, environment, spatial planning. Energy concept maps were developed based on sustainable energy action plans to build a common knowledge base. The use of the energy concept maps developed were tested by 24 lecturers and 206 students from six European countries, comprising Slovenia, Croatia, Portugal, Italy, Spain and Malta. The learning processes were evaluated based on self-evaluation of competencies as well as external evaluation of students’ knowledge and understanding of energy planning. The evaluation process revealed that participants included in learning activities gained new knowledge and competences in the energy planning and have a better understanding of a relationship between different concepts, subjects, developed a critical thinking, and proved their problem solving ability. Our study acknowledges the efficiency of the learning process in energy planning education by using concept maps.

Abstract

This study analyses co-benefit reductions of short-lived climate pollutants and air pollutants due to the effects of carbon dioxide mitigation measures for achieving a 2 °C global temperature change limit above pre-industrial levels. This study focuses on the following points: an estimation of technological mitigation potentials and costs of the greenhouse gases (a), and an assessment of co-benefit mitigations of short-lived climate pollutants and air pollutants in Asia due to the effects of low-carbon measures (b). Mitigation measures such as energy efficiency improvement in the demand sectors and the shift to less-carbon intensive or non-fossil fuel energies in the supply sector play important roles in reducing carbon dioxide as well as short-lived climate pollutants and air pollutants largely, especially in rapidly developing countries in Asia. Emissions of methane, black carbon, sulphur dioxide, nitrogen oxide, and fine particulate matter in Asia are reduced around 23%, 63%, 73%, 27% and 65% in 2050 correspondingly, compared to the 2010 levels due to the co-benefits in drastic carbon dioxide mitigation measures. These co-benefits are much larger than effects of taking measures only for air pollutant reductions.

Abstract

In urban areas of Uganda, management of waste which consists of at least 70% organic content is accomplished by collection and disposal in landfills, resulting in emission of landfill gases among other impacts. Meanwhile, the limited number of wastewater and sludge treatment plants makes further management of sewage and faecal sludge generated from urban areas a major challenge. Thus, integrated sanitation systems which consider combined management of organic waste streams, i.e. bio waste, animal waste, sewage and faecal sludge, are proposed. The sanitation systems consist of a combination of anaerobic digestion and other technologies such as composting, incineration among others. Moreover, the systems also promote resource recovery in the form of biogas and organic fertilizer. The environmental feasibility of the integrated sanitation systems was investigated using life cycle assessment method. The results indicated that resource recovery contributed to the environmental feasibility of these sanitation systems. The more resources that were recovered from the sanitation systems, the lower the environmental impact.

Abstract

In this study, an engineering economics software was developed to find the optimum design of renewable energy systems in micro-grid, off-grid, and on-grid cases.
The software was used to calculate the renewable energy production from photovoltaic and wind turbines in local regions in Korea. TMY2 files were made for the renewable energy calculation based on meteorological data from 28 locations in Korea. To calculate the output of the photovoltaic and the wind turbine, a power generation model based on theoretical equations was developed. A fuel cell and diesel engine generator can be selected to use as a base power source model, and a battery energy storage device was included for efficient energy management. To verify the results of renewable power generations from solar and wind, the models were compared with commercial programs such as TRNSYS and HOMER. The results showed good agreement under the same conditions. A sensitivity analysis for a grid-connected factory in a specific region was carried out and the optimum investment design condition for a renewable energy system to reduce costs through peak load reduction was calculated. The sensitivity analysis for off-grid and grid-connected system designs was also performed and it will be continued to improve the accuracy of the model by comparing the data with that from a demonstration complex. The developed program can provide useful information for investment decisions through the optimal design of facility capacity and economic analysis when investing in renewable energy supply facilities.

Abstract

The research addresses the present situation on the German electricity market caused by variable renewable energy sources. The increasing number of households with photovoltaic and battery storage systems and their impacts require special attention. These systems change the traditional electricity customer from the sole electricity consumer to an electricity producer and consumer in one person. These so-called prosumers differ in their actual electricity demand from the initially estimated electricity demand with standard load profile. This discrepancy results in deviations within a differential balancing group. Thereby, the main finding of this research is a significant higher balancing energy demand with the expansion of photovoltaic and battery storage systems. Hence, the standard load profile is particularly not suitable for differential balancing groups with a high penetration of solar systems and still less suitable for groups with solar and battery storage systems.

Abstract

Innovations are required in urban infrastructures due to the pressing needs for mitigating climate change and prevent resource depletion. In order to address the slow pace of innovation in urban systems, this paper analyses factors involved in attempts to introduce novel sanitary systems. Today new requirements are important: sanitary systems should have an optimal energy/climate performance, with recovery of resources, and with fewer emissions. Anaerobic digestion has been suggested as an alternative to current aerobic waste water treatment processes. This paper presents an overview of attempts to introduce novel anaerobic sanitation systems for domestic sanitation. The paper identifies main factors that contributed to a premature termination of such attempts. Especially smaller scale anaerobic sanitation systems will probably not be able to compete economically with traditional sewage treatment. However, anaerobic treatment has various advantages for mitigating climate change, removing persistent chemicals, and for the transition to a circular economy. The paper concludes that loss avoidance, both in the sewage system and in the waste water treatment plants, should play a key role in determining experiments that could lead to a transition in sanitation.

Abstract

Urban sustainability is one of the most prominent challenges in the global agenda waiting to be addressed since the Earth Summit in Rio de Janeiro. This research work applies a composite indicator that has been developed as the Sustainable Development of Energy, Water and Environment Systems Index to benchmark the performance of a new sample of 26 world cities. The sample advances the geographical diversity of previous samples and represents cities in the Global Covenant of Mayors for Climate and Energy as well as the C40 initiative. The benchmarking results are analysed based on quartiles of city performance and Monte Carlo simulations. The results indicate the top three cities in the sample to be Copenhagen, which obtains a score of 36.038, followed by Helsinki and Gothenburg. The top cities represent multiple best practices including those in district energy networks, water quality, and environmental management. A normative scenario up to the year 2050 is then applied to one of the cities in the sample, namely Rio de Janeiro. The normative scenario involves targets that take place in local plans, particularly Vision Rio 500. The benchmarking results for the new sample of 26 world cities and the normative scenario not only identifies the benchmark leaders but also underlines opportunities to pursue pathways in which higher levels of performance can be reached by cities that may face multiple challenges. The results of the research work holds significance for advancing the application of an original composite indicator to benchmark cities towards supporting the aim of decoupling economic growth from environmental pressures in more sustainable urban systems towards carbon neutrality. 

Abstract

The Journal of Sustainable Development of Energy, Water and Environment Systems - JSDEWES is an international journal dedicated to the improvement and dissemination of knowledge on methods, policies and technologies for increasing the sustainability of development by de-coupling growth from natural resources and replacing them with knowledge based economy, taking into account its economic, environmental and social pillars, as well as methods for assessing and measuring sustainability of development, regarding energy, transport, water, environment and food production systems and their many combinations.

In total 42 manuscripts were published in Volume V, all of them reviewed by at least two reviewers. The Journal of Sustainable Development of Energy, Water and Environment Systems would like to thank reviewers for their contribution to the quality of the published manuscripts.

Abstract

Three-sides artificially roughened solar air heaters perform better than one-side roughened ones under identical operating conditions. The present paper is an outcome of the experimental investigations conducted upon three- and one-side concave dimple roughened ducts. The present investigation is carried out under the mass flow rate range (0.0060-0.0250) kg/s, relative roughness pitch (p/e) 8-16 and relative roughness height (e/D_h) 0.018-0.045. Thermal performance characteristics of three-sides and one-side roughened duct has been analyzed, compared and validated. The variation in plate temperature along the test length of the roughened duct has an appreciable impact on the heat transfer from the plate to the underside flowing air. The collector’s surface temperature is found to be 21% lower in the three-sides than the one-side roughened duct. Plate temperature excess for both three-sides and one-side roughened duct has been analyzed and compared. The plate temperature excess range for three-sides roughened duct is significantly lower (12.5-28.5 °C) compared to one-side roughened duct (17.5-35.5 °C). The augmentation in fluid (air) temperature flowing under three-sides concave dimple roughened duct is found to be 34.87% more than one-side roughened duct. The augmentation in thermal performance due to the provision of roughness geometry in the form of concave dimple shape on the three-sides over one-side roughened duct is found to be 39-56% for varying p/e and 44-51% for varying e/D_h depending upon the operational mass flow rate of air and roughness geometry. The maximum thermal efficiency is obtained at relative roughness pitch of 12 and relative roughness height of 0.036. The results for efficiency ratio along with parametric variation influence on performance of the roughened ducts have also been discussed in detail.