Abstract

Decentralized electricity production solutions based on renewable energies are increasingly used in Africa to promote the social inclusion of the population in rural areas. In these areas not served by the electricity network, there are more and more network infrastructures installed by mobile network operators that are powered by genset. These energy sources only serve to provide electricity to the site elements while the local population lives without electricity. The use of microgrid based on renewable energies, particularly solar energy, on these operator sites can contribute to achieving goals 7 and 9c of the Sustainable Development Goals Indeed, intelligent management of these microgrids can ensure a continuous supply of electricity to the mobile network operators' sites and the use of excess production to offer electricity to the local population. To achieve this convergence between universal access to telecommunications and energy, based on these microgrids, the use of an optimization algorithm for better planning and operating efficiency of these microgrids is essential. To this end, the Particle Swarm Optimization algorithm was used for optimal power flow management in a multi-source and multi-load system to test the ability of microgrids to achieve this new objective. The obtained results showed that an optimal management of these microgrids guarantees a Loss of Power Supply Probability of 0.18 %, a Levelized Cost of Electricity of US$0.0187, and a Maximum Renewable Factor of 98%. Low cost of electricity  obtained shows that this solution is a real opportunity for increasing universal access to electricity for low-income populations in rural areas. Similarly, the Maximum Renewable Factor value obtained shows a reduction in the running time of the genset, with the consequence of significantly reducing operating costs and greenhouse gas emissions.

Abstract

Wastewater treatment plants are designed, operated, and maintained in light of environmental legislation, which mainly determines the removal of certain pollutants. This article proposes to comparatively assess the environmental and economic impacts of wastewater treatment technological routes commonly used in Brazil. For this purpose, life cycle assessment and life cycle costing were applied to four wastewater treatment processes, at two different scales. The results show the positive contribution of upflow anaerobic sludge blanket reactors in the flowcharts of the wastewater treatment plants to reduce the generation of environmental and economic impacts, by 3.15% to 84.53% and 25.03% to 38.68%, respectively. It can be concluded that the technological route that obtained the best environmental and economic performance is the upflow anaerobic sludge blanket reactor followed by a trickling filter, while the one that achieved the worst performance was activated sludge.

Abstract

The implementation of non-intrusive load monitoring has gained significant attention as a promising solution for disaggregating and identifying individual appliances' energy consumption within households and commercial buildings. The issue at the core of non-intrusive load monitoring is the accurate separation of the aggregated energy consumption signal into the energy contributions of distinct appliances without requiring additional sensors or invasive measurements. The erroneous implementation of non-intrusive load monitoring model leads to poor results and a waste of time where the criteria for the implementation are necessary. This paper presents an overview of non-intrusive load monitoring's implementation, addressing the stages of non-intrusive load monitoring and advancements in the field. The overview explores the various techniques, methodologies, and algorithms employed in non-intrusive load monitoring systems to achieve load identification and energy disaggregation. By addressing the problem statement and reviewing the state of the art, this paper sets the stage for understanding the significance of non-intrusive load monitoring in commercial buildings and modern energy-efficient households. Moreover, the limitations, applications, and recommended criteria for the implementation of non-intrusive load monitoring are highlighted as a contribution to the field of load disaggregation. Future research should address scalability, privacy concerns, and the integration of NILM with smart grids to propel energy disaggregation towards more efficient, accessible, and sustainable energy management systems. We envision that this endeavour can serve as a guiding beacon, offering a roadmap for researchers and professionals.

Abstract

Attaining the United Nations Sustainable Development Goals demands a partnership between industrial sectors. The power sector pulls the challenging goal of providing affordable and clean energy to society and industry, each with specific issues. This work recognises the need to address the three dimensions of sustainability and identifies a gap in the literature on indicators to assess the social dimension. In this context, the research presents the employment-weighted fair-wage potential, relating the electricity produced to social data, with ten power technology options. The proposed indicator ranks the alternatives, pinpointing the best technology based on social aspects. The analysis employs a social life-cycle approach with primary and secondary data, worldwide real and living wages, and employment factors. The findings indicate the values of the gas- and oil-based technologies as 3.55 and 3.51 at the operation and maintenance stages, respectively. In contrast, photovoltaics offers the lowest potential value (1.32), followed by biomass-biogas (1.86). Run-of-river emerges as the fairest wage potential option (3.33), followed by the reservoir (2.80), while Solar PV technology presents the lowest value (1.16).

Abstract

Thermogravimetric and kinetic analysis of biomass and plastic co-pyrolysis can provide valuable inputs for a better understanding of decomposition mechanisms. Such inputs are important for selecting the appropriate process conditions but can also be helpful for process modelling. This work investigates the properties of heterogenous sawdust in a mixture with polypropylene and polystyrene. Thermogravimetric analysis is conducted to determine the decomposition mechanism and kinetic parameters of investigated mixtures and to derive appropriate conclusions regarding their further utilization potential. Co-pyrolysis was performed on mixtures with the following biomass/plastic ratios: 75-25%, 50-50%, 25-75%, over a temperature range of 30-550 °C, at four heating rates 5, 10, 20, and 30 °C/min, with pure argon as a carrier gas. Obtained results were then subjected to comprehensive kinetic and thermodynamic analysis. The primary goal was to determine effective activation energies using model-free methods, pre-exponential factors, and elementary thermodynamic parameters such as changes in enthalpy, entropy, and free Gibbs energy. Finally, the influence of the heating rate and mixture composition was extensively investigated by analyzing calculated parameters.  

Abstract

In the paper, a direct water cooling system dedicated to photovoltaic panels has been developed and tested. In the beginning, the effect of temperature on power generation in the tested photovoltaic panels was determined. Furthermore, different configurations of the developed water cooling system were considered. Under laboratory conditions, an increase in the efficiency of a PV panel with a direct water cooling system was achieved at a level of 12% compared to an uncooled panel. The use of the direct water-cooling system under real conditions resulted in an increase in photovoltaic panel efficiency of 1.2 - 13.0%, while the average increase in energy production was 10.3%. Finally, the Simply Payback Time for installing the cooling system in typical domestic photovoltaic systems is less than ten years, while the Net Present Value ranges from -60.7 EUR to 178.6 EUR for a ten years period.

Abstract

The determination of the state of health of batteries is a necessary parameter for planning the acquisition of new units in storage systems for energy support. Currently, there are many investigations focused on determining the of the state of health of batteries of different types of batteries, as well as their useful life. However, none have analysed the of the state of health of batteries by changes in the transmittance of the electrolyte for a specific frequency, as proposed in this article. The project from which this article derives considered different health states of lead-acid batteries. The percentage of optical transmittance of the four central cells of the battery was analyzed, generating a classification pattern that allowed the approximate value of battery health to be obtained from the transmittance. The variation of the battery electrode is verified according to the changes in the state of health measured in the electrolyte. This method can be applied to batteries online. The proposed method for determining battery health is a non-destructive and cost-effective way to assess the remaining capacity of batteries. It could be used to extend the lifetime of batteries in storage systems and to help to ensure that systems have the capacity to meet energy demands.

Abstract

This paper presents a methodology based on the ISO-50001 standard to assess the energy impact of replacing standard efficiency motors with high-efficiency motors driven by variable speed drives in an industrial pumping system. The methodology includes the inspection and installation of the new technology, measurements, and data processing, as well as the analysis of the results. In addition, an energy efficiency indicator, an energy baseline, and a Pareto diagram are used, while the harmonics generated by new technologies are evaluated. The contribution of the methodology is that it allows for a comprehensive energy diagnosis using easily measurable data like electricity consumption and water flow, replacing the measurement of the motor's mechanical power in industrial conditions, which is a current challenge. The methodology applied in the case study showed that the technological changes made saved 36% of energy, and that the variable speed drives increased current harmonics by 10%.

Abstract

The depletion of non-renewable fossil fuels has led to the increasing importance of carbon-neutral resources like biofuel and biodiesel. Biodiesel is a better fuel option than petrodiesel due to its excellent lubricity, non-toxic nature, and lack of sulphur. However, the excess production of glycerol is a challenge for biodiesel usage. This study investigates the use of an acetylation process with palladium on the activated carbon catalyst to convert glycerol into triacetin, a potential fuel additive for biodiesel blends. The study optimizes the reaction parameters using response surface methodology to achieve high selectivity for triacetin. The study determined that the optimized parameters for achieving 96.64% glycerol conversion and 0.231% triacetin selectivity are 110˚C, a 1:10 glycerol-acetic acid mole ratio, and 0.718 wt.% catalyst loading. Analysis of variance revealed that the reaction temperature has a significant impact on glycerol conversion, while the glycerol-acetic acid mole ratio affects the selectivity of triacetin.

Abstract

The geotectonic environment of Central America provides the region with a high potential for harnessing geothermal energy, however, the use of this energy source continues to be scarce due to a variety of factors, including limited access to exploration-oriented resources. It is therefore a priority to generate information that facilitates the preliminary stages of geothermal projects in order to achieve a greater contribution of available renewable sources to the energy matrix. In this study, the MaxEnt model was employed to predict locations with geothermal potential in Honduras. The model incorporated the coordinates of 177 surface manifestations and utilized various predictors, including the distribution of volcanoes, geological formations, faults, aquifers, and surface temperature. These predictors were disaggregated into 23 environmental variables. A map with an adequate prediction precision (Area Under the Receiver Operating Characteristic Curve = 0.868) was generated, showing that except for the eastern central region of Honduras, the country has a significant prevalence of surface with high and very high probability of occurrence of geothermal manifestations. Among the variables analyzed, the occurrence of geothermal manifestations can be primarily attributed to the proximity to volcanoes in the region.

Abstract

With the emerging challenge of climate change, Norway has ratified to Kyoto Protocol, under the United Nations Convention on Climate Change. Thus, the role of renewables is critical not only in achieving the energy transition in Norway but also ensuring the necessary energy security resulting from the deployment of renewable energy sources. The concept of “four As of energy security” availability, accessibility, affordability and acceptability were introduced by (APERC, Asia Pacific Energy Research Centre, 2007). In this context, the paper attempts to analyze and examine the role of renewable energy (RE) deployment in ensuring energy security in case of Norway from 1990 -2017. Energy efficiency and deployment of renewable energy are two distinct pathways of energy transition. It is crucial to examine the relationship between them, whether there is trade-off or a positive correlation between the two plausible pathways of energy transition. Therefore, the paper evaluates the correlation between the energy efficiency and deployment of renewable energy. The four broad components of RESI such as availability, accessibility, affordability, and acceptability comprise of several indicators.  Using the appropriate indicators that explain the variables of four dimensions of RESI, an index is constructed by deploying a Principal Component Analysis (PCA), a dimension-reduction tool that can be used to reduce a large set of variables to a smaller set. During the initial years RE does not contribute to energy security in Norway indicated by negative values but from 2006 onwards, there is a gradual improvement in the status of renewable energy security, and the values become positive till 2010. Energy intensity increases with the availability of RE. Deployment of renewable energy and adopting energy efficiency technology are inversely related in the case of Norway. Accessibility of RE is significantly positively correlated with RESI. Similarly, the availability of RE is also highly correlated with RESI. More affordable renewable energy is, more significant is the security of renewable energy in Norway. The structural composition is significantly negatively correlated with RESI. It indicates any structural change in the share of energy-consuming sectors reduces the RESI. Finally, Research and development R&D in RE, investment in RE, the share of solar energy in the total electricity mix is significantly positively correlated with RESI in case of Norway. Renewable energy, R&D plays a crucial role in the energy transition in Norway while environmental concerns do not contribute significantly in the energy transition to renewables in Norway. Accessibility of RE, Availability of RE as well as Affordability of RE significantly improves the energy security in Norway.

Abstract

The article highlights producing plastic-reinforced bricks by incorporating recycled plastic pellets into cement mixtures to study the possibility of using recycled plastic waste as a sustainable alternative to traditional construction materials. The results showed that the production method effectively created durable and sturdy bricks without scattering or fragmentation in the recycled plastic reinforced bricks. Moreover, the plastic reinforced bricks gave a good possibility of paving together, similar to the traditional bricks. Employing plastic waste as a substitute for conventional concrete materials creates a sustainable and cost-effective construction material. The resulting weight of plastic-reinforced bricks with polypropylene pellets ranges from 2.74-2.89 kg, while the weight of plastic-reinforced bricks with polyethylene ranges from 2.75-2.91 kg, which is about 20% less than conventional cement bricks, offering potential advantages such as decreasing transportation costs, making the bricks easier to handle and install, and needing lower manufacturing power. However, compared to conventional cement bricks, the compression strength of the plastic-reinforced bricks is still lower, with the maximum compression strength ranging from 711-754 N/cm2 for polypropylene bricks and 521-655 N/cm2 for polyethylene bricks. The study also specified the length and shape of the plastic pellets as crucial factors influencing the strength and stability of the constructed bricks, suggesting that optimizing these aspects could lead to even stronger and more durable composite bricks

Abstract

Perception of temperature and relative humidity has an important influence on feelings of thermal comfort or discomfort. The aim of this study is to analyse the thermal sensations of 222 people aged 19 - 30 years, taking into account air temperature and relative humidity in four educational buildings at Kielce University of Technology. Two methods were used to conduct the study, indirect (use of an environmental meter) and direct (use of questionnaires). Air temperature ranged from 20^oC - 27.5^oC and humidity from 18.16% - 50.9%. Approximately 60% of the students rated the humidity as pleasant, nevertheless 32% would prefer it to be more humid.  Furthermore, thermal comfort was declared by 69% of the students, while 31% rated their feelings as uncomfortable. In addition, a correlation analysis was carried out for temperature and humidity.  In the overall assessment of the students, the buildings created good conditions for feeling comfortable.

Abstract

Mangroves are imperative to coastal systems, providing security against extreme weather events by acting as natural barriers. These halophytic plants play a crucial role in mitigating global warming and act as an invaluable resource for consumption. Despite proving to be resilient, mangroves exhibit sensitivity to climatic (e.g., Land Surface Temperature, Salinity, etc.) and man-made factors (e.g., Land Use/Land Cover Changes). Numerous past studies recording the relationship between mangrove growth & development with the aforesaid constituents, but those were mostly restricted to visual observation/pattern recognition and single type of regression analysis. Also, the evaluation of simultaneous exploration of multiple aspects influencing mangrove evolution was not prominent. Therefore, the main objective of this study was to focus on the impact of both salinity and land surface temperature on mangrove biomass by the joint-venture of remote sensing, geographic information system and several machine learning algorithms. The study considered appropriate mangrove site selections with pre-processing of the acquired satellite images. Also, mathematical computations were performed on the raster layers to determine the previously mentioned natural aspects. Finally, several types of regression analysis were conducted to delineate potential patterns, governing mangrove vegetation health by virtue of temperature and salinity. Mangroves’ relationship with temperature and salinity showed insignificant coefficient of determination. However, the generated response curves postulated that high mangrove biomass could be achieved for a specific temperature window (30-33◦C) and vegetation health could deteriorate at increasing salinity. Overall, combined effects of surface temperature and salinity on mangrove vegetation were significantly more (i.e., Maximum coefficient of determination of 0.31) than individual component alone.

Abstract

District heating networks are well-established technologies to efficiently cover the thermal demand of buildings. Recent research has been devoting large efforts to improve the design and management of these systems for integrating low-temperature heat coming from distributed sources such as industrial processes and renewable energy plants. Passing from a centralized to a decentralized approach in the heat supply, it is important to develop indicators that allow an assessment of the rational use of the available heat sources in supplying heating networks, and a quantification of the effect of inefficiencies on the unit cost of heat. To answer these questions, Exergy Cost Theory is here proposed. Thanks to the unit exergetic cost of heat, energy managers can (i) quantify the effects of thermodynamic inefficiencies occurring in the production and distribution on the final cost of heat, (ii) compare alternative systems for heat production, and (iii) monitor the performance of buildings’ substation over time. To show the capabilities of the method, some operating scenarios are compared for a cluster of five buildings in the tertiary sector interconnected by a thermal grid, where heat is produced by a cogeneration unit, an industrial process, and distributed heat pumps. Results suggest that moving from the centralized production of heat based on fossil fuels to a decentralized production with air-to-water heat pumps, the unit cost of heat can be decreased by almost 30% thanks to the improvement of thermodynamic efficiency. In addition, the analysis reveals a great sensitivity of unit exergetic cost to the maintenance in substations. The developed tool can provide thermodynamic-sound support for the design, operation, and monitoring of innovative district heating networks.

Abstract

Air-source heat pumps are strongly influenced by outdoor conditions, it is expected that ongoing climate changes may impact their operation. This paper presents a predictive analysis of the behaviour of air-source heat pumps in two cities with extremely cold and warm climates in the short, medium, and long term. The seasonal coefficient of performance and heat pump seasonal energy efficiency index are evaluated over the years, considering climate change for both locations. Climate change will shorten the winter period and prolong the summer. In winter, this results in a slight softening of the seasonal coefficient of performance and a reduction in operating hours. In summer, there is a slight increase in seasonal energy efficiency ratio values and hours of operation. The work highlights how the performance of the air-source heat pump, on average, will improve in winter due to an average increase in temperature. Heat pumps are expected to be used in the future and in geographical areas where they are not currently used due to the extreme winter temperatures.

Abstract

Thermal power plants require water for their cooling system. Water availability is a limiting factor for electricity generation. The water footprint is a tool used to quantify water appropriation. Its blue component quantifies the volumetric water consumption by the cooling system, while the grey component can quantify the effect of the cooling water discharge in the water body. Several authors have estimated the blue water footprint of the cooling system, but only a few have assessed how the discharged water may affect the water body's temperature. This paper assessed the thermal pollution produced by three Ecuadorian thermal power plants by estimating their grey water footprint. Results show that the grey water footprint can be up to three orders of magnitude larger than the blue water footprint of the plants, implying that the water bodies must have at least that volume of water to buffer the possible thermal pollution.

Abstract

This study offers a mechanism to control low-speed orientation using semi-active control. The semi-active system consists of a variable mass system and a torsional spring. The  torque generated by a variable mass system controls the platform’s orientation. An evaluation of the control system’s effectiveness is tested on a solar panel. The variable mass was represented by moving the water from one reservoir to another located at the left and right sides of the panel using an electrical pump. A solenoid valve controls the flow. The test results indicate that the energy consumption of electrical pump as actuators is reduced. Based on several references, the actuator energy consumption for controlling the orientation of solar panels was generally 2% - 3%, while in this study 0.79%.

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Abstract

The reduction of heating energy consumption and the mitigation of greenhouse gas emissions in the building sector has been an ongoing quest, especially in countries that rely on a coal-based energy sector where electricity and fossil fuels are used as the main heating solution in buildings. Many regulations are enforced to increase the building energy performance of existing buildings, however, there is a gap in the practical implementation of such regulations, especially in developing countries. Hence, this study presents the evaluation of the impact of existing regulations for building performance on the energy demand, cost, and environmental impact of block apartment buildings by testing four scenarios with different energy efficiency measures and heating, ventilation, and air conditioning systems. A numerical analysis is performed for the building energy performance assessment of a block apartment in Prishtina, Kosovo and a thorough statistical report is presented on the latest energy-related statistics in Kosovo to bridge the gap of the lack of available information on the building sector. After implementing the energy efficiency measures for the case study building, the results show a reduction of the heating load by 116.7 MWh/year, fuel demand by 243.49 kWh/year, and 86% carbon dioxide emission mitigation. These findings are important to promote the enforcement and practical implementation of existing regulations on building energy performance to building stakeholders and practitioners.

Abstract

As the shift towards renewable energy sources continues, new approaches for energy recovery from sewage sludge must be established. This paper explores the feasibility of implementing full-scale co-digestion of municipal sewage sludge with fruit biowaste through the synergistic effects obtained at laboratory scale. The efficiency/stability of the process was studied for three hydraulic retention times. By using simple tools to evaluate the performance of the anaerobic digestion system, such as the specific methane indicator and the energy potential recovery indicator, it was shown that the shortest retention time of 13 days had the highest methane production and almost doubled the specific methane production, thus contributing to sustainable waste management and energy self-sufficiency of wastewater treatment plants.