Abstract

To accelerate deep decarbonisation in the energy sector, the discipline of economics should focus on identifying feasible instead of optimal policies. To do so, economic analysis should include four features: complexity (a), non-economic aspects (b), uncertainty (c) and stakeholders (d). The aim of this paper is to show that qualitative scenario analysis represents a promising alternative to conventional optimisation approaches and meets these requirements. This paper develops qualitative scenarios for the case study of gas infrastructure modifications with hydrogen and carbon capture and storage technologies in Germany. In the results, the six socio-economic qualitative scenarios are described in more detail. A comparison between the case study and a conventional approach reveals three limitations of the latter and highlights the value of qualitative scenario development. The authors distil the advantages of qualitative scenario analysis and discuss challenges and chances, that go beyond the case study. In conclusion, developing socio-economic scenarios has a large potential to improve economic policy assessment. It also allows to catch up with the rethinking of energy research taking place in other disciplines.

Abstract

Wastewater heat recovery is currently an underutilized technology that could be part of solving the climate crisis. A large portion of the heat that leaves a building in the form of wastewater is potentially recoverable for pre-heating domestic hot water or other service water systems. While there are several different approaches to wastewater heat recovery, this project focused on creating detailed, integrated building models for wastewater heat recovery heat pump systems. EnergyPlus models were developed featuring inputs and assumptions corresponding to manufacturers’ specifications, performance lab test data and feedback from engineering consultants. EnergyPlus’s supervisory control Energy Management System objects were heavily relied upon to overcome modelling challenges. The developed EnergyPlus model was integrated into U.S. Department of Energy New Construction Reference Building models for various climate zones and building types to assess potential energy use, energy cost and greenhouse gas emission reductions.

Abstract

This manuscript deals in confirmation of drop in photovoltaic panel temperature under load. Two panels are compared, one with the load and other without the load. The panel under load should have larger heat dissipation (i.e. be cooler), when electrical yield is taken as an outgoing heat flow. During the experiment, a thermovision of the panels under solar irradiance was made with the thermal camera. Results of the first case show only minor change in panel temperature. Results of the second case, where one panel is under load, show reduced temperature of loaded panel, by up to 4 °C. Previously developed numerical model is updated with the measured data in the experiment. A measured electrical yield is taken into the account when the solar irradiance was modelled. Numerical model confirms the temperature drop and corresponds with infrared thermography data. Gained results can help in design of the photovoltaic systems, where more variants of operating conditions can be used in order to keep the panel on desired operating temperature.

Abstract

In this paper, residential area of 16 buildings with average annual 5.6 GWh heat consumption is studied in terms of distributed renewable energy supply with gradual separation from the local district heating network. Optimal heat supply and heat production capacities in the area are estimated by using hourly linear optimisation model for two separate model years and for normal and low district heating temperature cases. Results indicate that disintegration from district heating supply inflict 12-24% higher annualised total costs. However, completely removing the areal district heating network increases total costs considerably. Solution for heat supply in building area is a package consisting of ground source heat pump, heat storage and photovoltaics panel. Centralised ground source heat pump with centralised heat storage completes the heat supply cost-efficiently with low district heating supply levels. Solar collectors and exhaust air heat pumps are not cost-efficient solutions due to high investment costs.

Abstract

The objective of the work is to simulate a long-term process of eutrophication based on the concept of the aquatic ecosystem instability. A model assessment of qualitative effects associated with the development of a succession of aquatic communities during degradation of the ecosystem requires expanding the boundaries of the conventional approach. This raises the question of changing the structure of the reservoir ecosystem model. An idea of the Darwin’s principle of natural selection is the key point for assessing changes in the biodiversity structure. The problem was solved through consideration of changes in physiological activities of hydrobionts. The study based on biogeochemical cycles modelling revealed the change in the structure of the ecosystem. Also the novelty of the work is in the implementation of the method for structural-dynamic modelling to assess the trend of long-term eutrophication of the Novosibirsk reservoir, the largest in Western Siberia.

Abstract

In this paper an analytical model for calculation of entropy production for Nusselt model of condensation of pure substance vapour is given. Model development starts from basic two-dimensional integral equation for entropy production and describes film condensation on a vertical wall. Model covers entropy production, which is a result of two-dimensional heat transfer in a condensate layer, existence of velocity gradient and condensate layer viscosity. Entropy contribution of each of the members is explicitly derived in a closed form and the results of calculation are shown in the appropriate diagrams. Diagrams present film condensation of dry saturated water steam and dry saturated ammonia steam, both with saturation temperature of 100 °C with surface wall temperature of 98.5 °C. Obtained equations and presentation of the related results have shown that dominant entropy production is directly connected only with heat conduction in y-axis direction, where y-axis corresponds with thickness of condensate layer.

Abstract

The main focus of this paper is to address issues related with the impact of the small and medium size hydro power plants connected to the distribution network in Albania, respectively, to 35, 20, 10 and 6 kV distribution network. Considering the significant positive impact in generation they have had also an impact on the distribution system as far as the technical and financial aspects of the distribution network are concerned. The results of the analysis performed indicates that the Middle and South-East areas have been impacted from the deployment of hydro power plants in these area due to the increased power injected from these hydro power plants. Referring to the topology of the network, load demand, constrains and amortization of the distribution network, difficulties faced with the maintenance of the feeders and substations in the subject, this situation has created some problems and issues in respect of very high levels of the voltage in the substations during the minimum load consumption, overloaded of the distribution network as well as frequent outages of lines and feeders in some areas. The analyse performed supports the necessity of reinforcement of the network and the need of clear and strict rules to be followed in respect of connection point of hydro power plants into the distribution network, in order to guarantee a reliable and secured operation of the network and to contribute to the improvement of the performance indicators of the distribution network.

Abstract

Demand for domestic hot water and heating is rarely perfectly concurrent with solar irradiation, which means that collectors can overheat in periods of high incident radiation and low demand. Phase change materials have been used as energy storage in space heating applications to absorbs excess heat during low demand periods for use in peak demand periods. This paper reviews the current state of research on the possibility of application of such materials as energy storage for solar collectors, in order to avoid collector overheating. Finally, various materials were evaluated and ranked for this application based on required properties and price. An example model of such materials being applied in a typical family house domestic hot water solar system is also provided.

Abstract

The management of a water network metabolism depends on the estimate of incoming and outgoing flows related to the life cycle of the products and processes involved. This type of analysis can be used, in an equivalent manner, to estimate the environmental loads associated with products and processes, providing a useful support to define the sustainability level of a water network. The Life Cycle Assessment, in these contexts, is often used in association with other methods for estimating metabolism. In this work the impact analysis of input and output flows of the Rende (Italy) water network is proposed, aimed at estimating the cost of its metabolism, in terms of global impact, referring to the materials making up its hydraulic elements.

Abstract

Transformation concepts towards a low-carbon society often require new technology and infrastructure that evoke protests in the population. Therefore, it is crucial to understand positions and conflicts in society to achieve social acceptance. This paper analyses these positions using the example of implementing hydrogen and carbon capture and storage infrastructure to decarbonise the German energy system. The empirical basis of the study are explorative stakeholder interviews which were conducted with experts from politics, economics, civil society and science and analysed within a discursive and attitudinal framework using qualitative content analysis. These stakeholder positions are assumed to represent dominant social perceptions and reflect chances and risks for acceptance. The results indicate different positions while pursuing the common goal of addressing climate change. The general conflict concerns strategies towards a low-carbon society, especially the speed of phasing-out fossil energies. Regarding the combination of hydrogen and carbon capture and storage as instrument in the context of the energy transition, the stakeholder interviews indicate controversial as well as consensual perceptions. The assessments range from rejection to deeming it absolutely necessary. Controversial argumentations refer to security of supply, competitiveness and environmental protection. In contrast, consensus can be reached by balancing ecological and economic arguments, e.g. by linking hydrogen technologies with renewable and fossil energy sources or by limiting the use of carbon capture and storage only to certain applications (industry, bioenergy). In further decisions, this balancing of arguments combined with openness of technology, transparency of information and citizen participation need to be considered to achieve broad acceptance.

Abstract

Compared to a traditional turbine (Kaplan, Francis, Pelton), pumps operated as turbine are a good alternative for micro hydroelectric power plants thanks to their low cost and easy availability. This paper presents a review of the most challenging aspects of the pump as turbine: prediction and improvement in turbine mode. First, an explanation of the theory of the pump as turbine focused on the functioning, types of pumps, selection criteria and performance predictions as shown in the literature, giving also methodologies and details on the pump as turbine selection. Afterwards, the literature shows the instabilities produced by the operation of the pumps on inverse mode, which generates S-shape curves and cavitation. Finally, as the main focus of this paper, aspects of efficiency produced by geometric parameters were discussed. Current trends and future scope for further improvement and implementation of pump as turbine are also discussed.

Abstract

Agro-food industries produce large amounts of wastes challenging innovative and efficient valorisation strategies promoting the circular bioeconomy concept. Anaerobic digestion technology is an interesting route for bioenergy recovery in the agro-food chain sector. In this work, a simple approach is proposed for assessing energy performance of livestock manure and mixed sewage sludge, as substrate by coupling the potential addition of several agro-food biowastes (co-substrate: fruit and vegetable biowastes, fish canning industry, other manures, coffee wastes, and non-edible crops). The results obtained showed an increase of energy performance indicator ranging from 30 to 250% and 62 to 539%, for livestock manure and mixed sewage sludge, respectively. This conceptual approach for feedstocks promotes the circular bioeconomy as it encourages the stakeholders to a smart use of anaerobic biotechnology at rural-level or urban-level.

Abstract

The cost of treatment of produced water prior to disposal forms a significant percentage of the total economic impact of pollutants in crude oil production. The treatment of produced water involves the removal of toxic compounds contained in the fluid to a level where it is considered safe before the water can be disposed, discharged or reused in the environment. Production chemicals have been identified as one of the sources through which these toxic compounds enter the produced water and therefore the need to evaluate the influence of these chemicals at their various injection rates on the quality of the produced water from the production process. This research study is a part of an on-going project on the application of environmental process engineering for pollutant reduction and energy savings in crude oil production. The study has found that the introduction of scale inhibitor, paraffin inhibitor, demulsifier, biocides and corrosion inhibitor at the rates of 10 ppm, 200 ppm, 15 ppm, 500 ppm and 10 ppm, respectively, yields a corresponding increase in the concentrations of ammonia, hydrocarbons, salinity, phosphates and nitrates in the produced water by 242%, 53%, 12.5%, 300% and −4.8%, respectively. The knowledge provided by this project will educate the oil and gas sector across the globe, aid engineers and operators understanding of produced water pollution mechanism during oil and gas production processes. The results of this research will also be useful in the design of crude oil production and produced water treatment processes in avoiding negative environmental impacts from the final effluent composition of produced water.

Abstract

This paper aims to present the approach to the creation and rendering of a detailed solution for cooling plants including all supporting documents. The paper presents all steps and specific sub steps of the presented approach and the approach has been verified on an example of a cooling plant with water-cooled chillers in the pharmaceutical industry. The authors were motivated to use such approach to find an expedient and high-quality solution for the system architecture. They believe that optimal cooling plant system architecture can be provided by an adequate selection of the required equipment and all system parameters it needs to comply with, through two phases of evaluation analysis, including all supporting technical documents. The approach is based on the designers’ engineering knowledge and years of experience in this field. It is based on a so-called Configuration and Change Management approach where the required/acceptable solution is provided by configuring the product and changing product properties through several loopback steps. The approach is quite comprehensive and complex, however, it produces a satisfactory solution with well presented results, which makes it applicable to the creation of new cooling plants.

Abstract

Abstract

This study shows that as a result of exergy destructions in heat recovery ventilation units, additional but avoidable carbon dioxide emissions take place due to the imbalance between the unit exergy of thermal power recovered and the unit exergy of fan power required to overcome the additional pressure drop. Therefore, special attention needs to be paid in the design and control of heat recovery ventilation units to minimize such carbon dioxide emissions responsibility by a proper exergy-rational balance between the heat recovered and power required. The potential improvements about the exergy rationality of the heat recovery ventilation units were investigated for several alternatives. These alternatives were: heat recovery ventilation-only (base case), coupling with an air-to-air heat pump in tandem or parallel to the heat recovery ventilation unit, and a heat pump-only case. To carry out such an investigation, a new exergy-optimum design and dynamic control model was developed. Under typical design conditions, this model showed that a heat pump in parallel configuration does not improve the exergy rationality unless its coefficient of performance is over 11, which is not practical with today’s technology. Instead, passive solar and wind energy systems have been discussed and recommended. Results were also compared with condensing boiler, micro-cogeneration unit, fuel cell, and electric resistance heating cases. It has been shown that heat recovery ventilation with an air-to-air heat pump in tandem is the best in terms of the exergy-based coefficient of performance. Additional comparisons were made concerning avoidable and direct carbon dioxide emission responsibilities, climate warming-potential and ozone-depleting potential, embodied energy, embodied exergy, and carbon dioxide recovery periods. A new composite index, which recognizes the direct relationship between the ozone layer depletion and the greenhouse gas emissions has also been introduced for comparing system alternatives in terms of their atmospheric footprint.

Abstract

The goal of this work is to apply Multiple Criteria Decision Analysis tools, both theoretical and practical, to analyse, support and possibly enhance composite indexes, in particular those related to sustainability assessment. In this context, the Sustainable Development of Energy, Water and Environment Systems Index represents a paradigmatic example and an emerging reference point, thus it is specifically addressed throughout the work. On the theoretical side, the focus is on the property of “independence”, i.e., of evaluating an alternative independently of the others. It is argued that this property can be appealing for an index that is conceived to address, over time, an increasing number of inherently evolving systems. A viable and theoretically grounded approach for devising a version of the index fulfilling independence is proposed. On the practical side, the contribution concerns visual support tools. A well-known projective method is adapted to work with the index, and a new tool with comparable expressive capabilities is proposed. The new representation is more focused on the index, technically simpler, and less sensitive to changes in the input data. The features of the visual tools are illustrated exploiting currently available (partially aggregated) index data. In particular, the new tool is used to illustrate two issues addressed in the scientific literature on the index, namely, the use of scenario analysis as a predictive tool, and the decoupling of energy usage and carbon dioxide emissions.

Abstract

Power plants supplied by renewable energy sources are expanding around the world, in order to reduce the carbon dioxide emissions, limit the global warming and improve the energy sustainability. Despite the relevant achieved results, small islands are heavily reliant on fossil fuels. In this context, renewable energy sources are available but practically unused, due to landscape and economic constraints. This condition is quite common in the Mediterranean Sea. These islands are normally fed by a stand-alone electrical grid and a power plant, equipped with diesel engines. In order to improve the sustainability of the energy sector, the paper considers the case study of Ustica, a small Italian island located north of Sicily. Starting with the analysis of the electrical energy consumption of public buildings, the paper suggests a more sustainable energy mix, based on solar and sea wave. An innovative technology is presented to exploit the sea wave energy source while commercial photovoltaic panels are adopted for the utilization of solar radiation. A mathematical model is introduced to realize a preliminary sizing of the energy mix. An environmental and economic evaluation is performed, demonstrating the feasibility of this solution. The approach reported in this paper can be easily replicated in other small islands, obtaining similar results.

Abstract

The paper aims to explore the effect of different passive cooling measures using thermal modelling and predicting. Solar shading, green roofs and cool paints were incorporated as passive cooling measures to evaluate their combined effects on indoor environment, thermal comfort and its importance in energy conservation. A field experiment study was conducted in the sub-Saharan climate of Kiambu, Kenya where microclimate indicators were measured for validating and predicting the thermal behaviour. For this study, both mechanical and natural ventilation were restricted. Modelling and prediction were done in Design Builder and EnergyPlus software. The computer model was validated with data measured for 20 days on the field. A correlation value of 0.85 between the predicted values and the observed values was recorded. This result shows that this energy prediction process can provide reasonable predictions in cooling loads and the effect of passive cooling in reducing indoor temperature gains.

Abstract

A wide range of published scientific articles on metal content in printed circuit boards show that it is necessary to determine the content of individual metals. The aim of this paper is to show how metal content varies according to the type and age of waste electrical and electronic equipment collected in the Republic of Croatia. Samples of cell phones, TV sets, and computers are collected. The metal content is determined for electronic components and printed circuit board base plates separately for different grain sizes (1-4 mm, 0.5-1 mm, 0.1-0.5 mm and < 0.1 mm). The results show that electronic components form a larger part of printed circuit board mass fraction depending on the equipment age and type. Generally, electronic components do have a higher mass fraction for most metals (like: aluminium, copper, nickel, zinc, gold, and silver in most cases) in comparison to printed circuit board base plates, but for certain metals (like: lead, tin) the opposite applies. The electronic components of larger grain sizes (1-4 mm and 0.5-1 mm) contain more aluminium, copper, and zinc, and less lead, while the smaller grain size fractions are richer in gold. The bare boards base plates of larger grain sizes contain more copper, lead and tin, while the smallest grain size class (< 0.1 mm) contains more aluminium and gold. No clear trends are noticed in the case of silver and lead.