Abstract

Regulation EU no. 517/2014 on fluorinated greenhouse gases (the F-gas regulation) and today’s research in the refrigeration and air-conditioning technology and heat pumps are increasingly focused on the use of natural refrigerants such as ammonia, carbon dioxide and hydrocarbons. Besides having zero ozone depletion potential, refrigerants should have their global warming potential as low as possible. In a way, the said Regulation promotes the use of sustainable technologies and sustainable natural refrigerants in refrigeration systems. The paper gives an overview, application and basic properties of refrigerants in refrigeration equipment and heat pump systems divided in different categories. The emphasis is on natural refrigerants that are gradually being used as a replacement for refrigerants from the hydrofluorocarbon group. Furthermore, the hydrofluorocarbon refrigerant group is analyzed in the context of F-gas regulation. Also, the hydrofluoro-olefin refrigerant group, which is currently being used in automotive cooling systems, is listed. The mentioned refrigerant group is widely recognized as the next generation of refrigerants due to its favourable environmental properties and cost-effectiveness. The paper also contains total equivalent warming impact number calculations of cooling plants for cooling buildings with a known cooling load.
The comparison is given for different types of refrigerants with the purpose of better understanding their ecological impact. Results indicate that the natural refrigerants are the best option since their ecological impact is negligible.

Abstract

Abstract

A renewable-based system able to meet pure electric, space heating and cooling loads of a small office building located in Southern Italy is evaluated here. The proposed energy conversion system is based on a photovoltaic plant, an electric-driven heat pump and electrical energy storage. Energy and environmental performance of this system has been evaluated by means of a dynamic simulation software changing photovoltaic nominal power (4.5-7.5 kW), battery capacity (3.2-9.6 kWh), and reference electrical system. The aim of the paper is the energy and environmental comparison on monthly, as well as, on yearly basis between the proposed system and the reference conventional system.
The conventional system is based on the power grid, a natural gas fired boiler and an electric-driven chiller. The analysis here reported shows how monthly variation of electric reference system, due to different monthly Italian electricity mix production, influences the energy and environmental performance of the solar-based system.
The proposed system guarantees high primary energy saving and equivalent carbon dioxide emissions reduction up to about 93%.

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 48 manuscripts were published in Volume VI, 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

This paper examines the inter-linkages between the water and energy sectors and their planning processes, by describing a comprehensive analytical tool developed to evaluate water energy nexus operational cost trends and planning to assist decision makers in exploring and evaluating alternative courses of action. Brazil has been chosen as a case study, because its electricity production is highly dependent on water to keep affordable tariffs, which in turn also serves as input to other important sectors, such as water services and sanitation, and raises disputes especially in basins marked by water scarcity, such as the São Francisco basin. In light of hydrological factors (e.g., droughts) and non-hydrological factors (e.g., chronic delays in delivery of new plants) there has been water availability constraints for electricity generation and energy prices have risen, while water quantity and quality have decreased for multiple users. Both of which impact negatively on water services and sanitation providers, because electricity figures as their fastest growing costs in times when they need more energy to source water from longer distances, or deeper levels because of water quantity and quality issues. Energy and water are characterized as common pool resources with planning processes along silos in Brazil that do not serve well the purpose of sustainable development. Better integrated water-energy plans at basin level is the alternative proposed under this paper to advance sustainability and mitigate the risks related to water scarcity that have resulted in negative impacts on both electricity and water sectors.

Abstract

The article provides the results of experimental studies of the effect of air introduction into a gasifier, the fuel particle size, and the recovery zone height on a content of carbon monoxide in wood gas. The mathematical models of wood gas formation presented in the scientific research have uncertain boundary conditions. For adequate use of the mathematical models numerous hypotheses are needed. Therefore, it is essential to acquire experimental data in the actual range of gasifier operation parameters. The research of influence of the gasifier design and operation parameters on the concentration of carbon monoxide in wood gas was conducted in the laboratory using a specially developed plant. The plant consisted of a gasifier with adjustable height of recovery zone and centrifugal air blower with adjustable rate of air introduction into the gasifier. The downdraft gasifier with combined combustion and recovery zones was used. These zones had a diameter of 200 mm. The thermal power of the gas generator was 5 kW. Hardwood with different size range was used as the raw material. The results of the experimental study lead to the establishment of rational values of the recovery zone height that provide the maximum concentration of carbon monoxide at various values of the fuel particle sizes and introduction of air into the gasifier.

Abstract

The main problems in wireless sensor technologies are the constrained energy resources (e. g., battery capacity, processing consumption), and their long-lasting operational capacity in the environment while collecting and sending data to the central station. So, in the design and development of wireless sensor networks, one of the main challenges is to achieve maximal battery life. Real time monitoring by implementation of wireless sensor networks contributes to minimization of potential production risks, emerging mainly from environmental influences and human actions. The main goal in this paper is to obtain minimal energy consumption of wireless sensor nodes while collecting distributed data in environmental parameters monitoring. The communication module and the controller should be in idle state as long as possible when they are not active. Energy consumption changes with the frequency of the transmitted measurement data by the sensors and send/receive configuration of the radio frequency modules. Therefore, all of these parameters should be chosen carefully in order to create an optimal environmental monitoring system. In this contribution the stochastic optimization method-genetic algorithm is used to minimize the energy consumption of the wireless sensor nodes depending on the frequency of the transmitted data and the period of the transmission process. The optimization method is implemented for different scenarios while the frequency of the transmitted data is increasing and the period of transmission of all the active components in a sensor node is increasing.

Abstract

This article analyzes the case of a Brazilian Institute of Higher Education, in relation to compliance with a normative instruction, according to which all federal public buildings must follow the rules of energy efficiency. The aim of this work is to demonstrate the potential of Building Information Modeling to optimize the execution of reference instructions. As a case study, the energy efficiency of one of the Institute buildings was observed using the conventional method and a new method. Subsequently, a comparative analysis was carried out to indicate the most appropriate procedure for the Institute. Finally, it was observed that the new method showed an approximately 85% reduction in classification time due to its better performance in obtaining architectural design information and, if incorporated in the routine of the project, will contribute more adequately to the interests of the Institute.

Abstract

It is claimed that ‘Big Data’ could help cities become ‘smart’, utilise resources more efficiently, and improve inhabitants’ quality of life. Metered consumption data of electricity, gas and water are collected and stored for each household in Australia and provide a valuable source of information for researchers hoping to understand the patterns of consumption and improve resource utilisation. This work tests the assumption that these datasets are sufficiently ‘clean’ to allow interrogation and details the common errors encountered. An inspection of 1-7 years of meter readings of electricity, gas and water for ~60,000 households in Canberra, Australia as well as all datasets of the local government’s energy and water efficiency programs, found this not to be the case. Common errors found include: missing data, biases in erroneous data, errors generated by the data custodians, duplicate entries, the effect of different custodian objectives and of poor data constraints (free flowing text).

Abstract

Sour water are aqueous waste streams from oil refining operations, heavily contaminated with hydrogen sulfide and ammonia, which need to be stripped before reuse or disposal, avoiding damages to process and environment. Two-stage sour water stripper units are the most common technology to treat sour water for hydrogen sulfide and ammonia separation to produce reusable water and send these species respectively to Claus and ammonia plants. The first stage of a two-stage sour water unit is responsible for properly splitting hydrogen sulfide and ammonia. This work uses surrogate models to predict the limiting point of hydrogen sulfide separation in the first stage of a sour water unit, allowing more efficient heat duty control strategies to achieve the difficult split of hydrogen sulfide and ammonia and simultaneously lowering heat consumption. Failure of compliance to this limit results in unspecified stripped gas from the first stage, impeding it to directed to Claus plant, entailing loss of sulfur production and higher load of pollutant emissions from flared gases. Therefore, a precise surrogate predictor was developed to dynamically define a quasi-optimum set-point to the controller of the first stage reboiler duty based on dynamic disturbances – the first stage input factors to the surrogate model, such as hydrogen sulfide and ammonia contents of the sour water. The new control policy outperformed the traditional first stage ratio control in terms of stripped gas composition and plant stability.

Abstract

Offshore production of oil and natural gas with high carbon dioxide content and high gas-to-oil ratio entail stringent processing conditions that require innovations and first-of-a-kind designs, which bear uncertainties derived from the scarcity of commercial-scale projects, hindering to move along technology learning curves. Consequently, unpredicted scenarios and unachieved specifications cause economic and environmental losses. Such uncertainties force offshore plants to be designed under stochastic factors seeking best statistical performance. The Monte Carlo Method is suitable to such finality. This work proposes a computer-aided engineering framework ‘MCAnalysis’ automatically applying a probabilistic environmental assessment of offshore gas processing. ‘MCAnalysis’ integrates HYSYS simulator with ‘Waste Reduction Algorithm’ to assess potential environmental impacts, whose most relevant categories were identified via Principal Component Analysis. An offshore plant processing natural gas with high carbon dioxide content was submitted to probabilistic raw gas flow rate under two scenarios of carbon dioxide content. The higher carbon dioxide content scenario presented the highest probabilistic potential environmental impacts, being the atmospheric category the most relevant.

Abstract

In this study, zinc oxide, zinc sulfide and zinc selenide semiconductor thin films were produced by Chemical Bath Deposition technique with and without annealing. The structural, surface and optical properties of the obtained thin films were determined to specify effect of annealing on thin film properties. Characterization results indicated that, the produced zinc-based thin films have polycrystalline nature. Both zinc sulfide and zinc selenide thin films have cubic and zinc oxide thin films have hexagonal structure. The surface morphologies of all thin films are homogeneous and compact. The optical band gap values of the obtained thin films are close to the band gap of zinc-based semiconductors. The annealing processes neither improved the crystal structures nor altered the band gap values of zinc-based thin films. Agreeable to characterization results, production of zinc-based thin films via chemical bath deposition technique without annealing is facile, economic and energy efficient so can be used for many thin film applications.

Abstract

A novel approach to hybrid hydraulic vehicles drive component sizing methodology based on the Willans Line method is proposed in this paper. The proposed method is used to develop a scalable mathematical model of hydraulic unit efficiency maps, thus helping the designer regarding an appropriate hydraulic unit choice when target unit data is difficult to obtain. The hydraulic unit efficiency model is also verified against catalogue data for different unit sizes, and the method is validated by means of detailed approximation error analysis. The proposed method can be particularly useful in optimal component sizing and parameterization studies of hydraulic drives in general, with possible applications to hybrid hydraulic vehicle power-trains.

Abstract

This study evaluates the energy and environmental performance of a cogeneration system operating simultaneously with bagasse and straw in a rankine cycle. Different process conditions, defined in terms of boiler operating pressure, moisture content and straw addition rate, were analyzed. The combination of these parameters led to the elaboration of one hundred and twenty-five analysis scenarios. The energy profile was based on the energy performance indicator, which is the ratio between the exported electricity and the intrinsic energy of biomass consumed for its generation, and the environmental assessment was performed in terms of climate change. Scenario modeling was developed according to the conceptual framework proposed by the life cycle assessment technique with a ‘from cradle-to-gate’ coverage. Results indicate that the best energy and environmental performances (energy performance indicator = 0.193 and 688 kg CO_2eq/MWh) were obtained with the highest pressure (100 bar) and addition rate (50%), and the lowest moisture content (10%). Moreover, straw moisture has more influence on the system environmental performance than its addition rate.

Abstract

In Europe, the introduction of high-efficiency cogeneration regulatory has radically changed the incentive scheme for cogeneration power plants that, in turn, inevitably affected the evaluation of techno-economic feasibility of new cogeneration plants. In this regard, selection and optimal design for cogeneration systems need to be investigated in the light of the new regulatory context. The first objective of this paper is an in-depth characterization of crucial industrial sectors aiming to define their average specific electric and thermal energy consumption, in addition, a detailed characterization of each cogeneration technology is provided, so as to identify the most significant cogeneration performance. Then, based on both energy requests of industrial processes and cogeneration performance, a specific procedure is applied to each of the analysed technology for a proper selection and design of a cogeneration system within the new high-efficiency cogeneration regulatory context. Finally, a total key performance indicator has been defined with the purpose to choose the technology best suited to a specific application so that the optimal solution can be immediately identified among a variety of possible ones. The result of this work represents an objective proposal of cogeneration technologies for different industrial processes application as a function of their energy requirements and production.

Abstract

New and improved energy storage technologies are required to overcome non-dispatchability, which is the main challenge for the successful integration of large shares of renewable energy within energy supply systems. Energy storage is proposed to tackle daily variations on the demand side, i.e., storing low-price energy during off-peak or valley periods for utilization during peak periods. Regarding electrical energy storage, several technologies are available with different potentials for scalability, density, and cost. A recent approach for grid-scale applications is based on transcritical carbon dioxide charge and discharge cycles in combination with thermal energy storage systems. This alternative to pumped-hydro and compressed air energy storage has been discussed in scientific literature, where different configurations have been proposed and their efficiency and costs calculated. The potential of the concept has been demonstrated to be an economical alternative, including hybrid concepts with solar thermal storage. Even at low temperatures, the addition of solar energy has proved to be cost effective. This paper explores the effect of introducing solar-based high temperature heat on the performance of different configurations of “Transcritical carbon dioxide ‒ thermal energy storage system” cycles. A base-cycle with 8-hour discharge time is compared with different layouts. Discussions include details on the models, parametric analyses -including solar technology alternatives-, and simulation results. Round trip efficiency of the base case, without solar support and at pressure ratio of 9.4, is 52%. When solar input is considered, the efficiency is above 60%, increasing the turbine inlet temperature to 950 K. Estimated levelized cost of electricity values are in the range of pumped hydro and compressed air energy storage, 90-140 USD/MWh in agreement with other works on this thermal storage technology. The global analysis shows clear advantages for advancing in the study and definition of this technology for exploitation of synergies at different power ranges, integrated with mid/high temperature solar power plants and with smaller-scale renewable installations.

Abstract

Thermal comfort and energy saving have become a priority for construction industry professionals. An important parameter of the comfort is the mean radiant temperature and its dependence on the building envelope. In the present research, a dynamic physical model has been studied in a climatic chamber, linked to the specific heat (C), density (r) and thermal conductivity (l). The heat capacity is usually quantifiable in small, homogeneous and uniform samples by the application of calorimetric methods. Consequently, the building energy consumption assessed through calorimetric methods, is often quite different from the energy consumption measured in situ. In this work an experimental model for the assessment of specific heat of real-size building components is proposed. Such a parameter was determined by measuring the heat flow through a building wall. The model has been validated by comparing the evaluated properties of known materials for different thermal gaps.

Abstract

This work presents a case report related to the management and the monitoring of a hybrid photovoltaic-wind system with battery energy storage, installed at the administrative offices building of the municipality of Valderice (Italy) within the framework of the Italy-Tunisia ENPI cooperation project Le Développement Durable Dans la Production Energétique Dans le Territoire (DE.DU.ENER.T.). The paper describes the hybrid system and briefly reports the monitoring data for a whole year, comparing the real production with the expected one and evaluating some performance indexes of the system. The performance indexes are very simple and have been defined only with the purpose of showing the advantages of distributed generation. Then, two different control logics for the battery energy storage systems are compared in order to define the most suitable management of the local energy resources, in presence of different Time-of-Use electricity tariffs. In particular, the two logics are compared by varying the difference between the electricity prices in peak hours and in off-peak hours and the rate between the electricity consumption of the building and the battery energy storage’s capacity.

Abstract

Improving urban sustainability requires an understanding of the determinants of resource consumption. The determinants of such consumption are poorly understood despite more than 40 years of investigation. Detailed exploration requires data at the dwelling scale. Such data are usually difficult or expensive to collect. This work derived dwelling-level statistics for each of ~200,000 dwellings in the city of Canberra, Australia. Swimming pool locations and size were derived from satellite imagery (a); household wealth was estimated from unimproved land value (b); summer daytime micro-climate temperature was estimated from thermal satellite imagery (c) and environmental attitudes were estimated from the interpolated percentage of Greens party votes from polling station election results (d). All four variables were correlated with residential water consumption. This work demonstrates how these explanatory variables can be derived from publicly available datasets and at low cost. It also shows their value in understanding the determinants of household water consumption.

Abstract

Global society is confronted with various challenges: climate change should be mitigated, and society should adapt to the impacts of climate change, resources will become scarcer and hence resources should be used more efficiently and recovered after use, the growing world population and its growing wealth create unprecedented emissions of pollutants, threatening public health, wildlife and biodiversity. This paper provides an overview of the challenges and risks for sewage systems, next to some opportunities and chances that these developments pose. Some of the challenges are emerging from climate change and resource scarcity, others come from the challenges emerging from stricter regulation of emissions. It also presents risks and threats from within the system, next to external influences which may affect the surroundings of the sewage systems. It finally reflects on barriers to respond to these challenges.