rss_2.0Environmental and Climate Technologies FeedSciendo RSS Feed for Environmental and Climate Technologieshttps://sciendo.com/journal/RTUECThttps://www.sciendo.comEnvironmental and Climate Technologies Feedhttps://sciendo-parsed.s3.eu-central-1.amazonaws.com/65c79736c8e7241308659c32/cover-image.jpghttps://sciendo.com/journal/RTUECT140216Effectiveness of Water-Amine Combined Process for CO Extraction from Biogashttps://sciendo.com/article/10.2478/rtuect-2024-0012<abstract> <title style='display:none'>Abstract</title> <p>The EU countries are implementing biomethane production projects from biogas, supplying it to the natural gas distribution grid, or using it as motor fuel. It is also extremely relevant for Ukraine, supposing the problems with gas import due to Russian aggression. Biogas production from landfills, agriculture waste, and sewage is already implemented in Ukraine, so the next step must be biomethane production on an industrial scale and the selection of biogas separation technology is important. Using 11 years of industrial experience in biogas production from landfills, wide experience of the different methane-containing gases separations, and small companies’ industrial possibilities, the most applicable separation technologies for Ukraine were selected: amine, water, and combined water amine carbon dioxide separation. These technologies had compared using computer simulation with real landfill biogas flow rate debt. Results of a software simulation of the most applicable water-amine absorption technology were verified using a laboratory setup. For carbon dioxide concentration in biogas at 32–42 % vol., the specific energy consumption when using water absorption is on average 2 times less compared to amine absorption, but at the same time, the loss of methane due to its solubility in water during water absorption amounted to 7.1–7.6 %, with practically no losses in amine absorption, and minor losses at 0.17–2.8 % in combined water-amine technology. The energy consumption of combined water-amine absorption is comparable to that of water absorption due to: a) reduction of heat losses for the regeneration process of saturated amine absorbent, as part of carbon dioxide has already been removed with water technology; b) using the methane excess to compensate power consumption of the biogas compressor during the preliminary water absorption of carbon dioxide and/or to compensate heat costs of the saturated amine absorbent regeneration</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00122024-03-25T00:00:00.000+00:00Research of Insertion Loss of Multilayered Construction with Devulcanized Waste Rubberhttps://sciendo.com/article/10.2478/rtuect-2024-0011<abstract> <title style='display:none'>Abstract</title> <p>In this study, the insertion loss of devulcanized waste rubber baffles were evaluated. Acoustic baffles are suitable to reduce noise from the devices or machines by interfering with their emitting sound waves. Knowledge of the acoustic properties of the material used is of significant importance in ensuring the effectiveness of the acoustic properties of the baffle. Basic properties include airborne sound insulation, which is usually determined during laboratory tests. Baffles consists of sound absorbing and sound insulating materials. In this study, plasterboards were used as sound insulating material and devulcanized waste rubber as sound absorbing material. During the devulcanization process, porous granules are obtained, which can be used as an acoustic material. In this study, two types of rubber granules were devulcanized by grinding method and one other type was chemically devulcanized. Three types of rubber granules were mixed together in increasing 25 % proportion steps and glued with patented polyurethane glue. A total of 15 different composition devulcanized waste rubber granule boards were made. Rubber boards were attached together with the plasterboards. Insertion loss of the different composite baffles was measured in semi-anechoic chamber in a purposefully designed stand in 1/3rd octave bands. The results showed that the insertion loss of the baffles was mostly dependent on the rubber granule board density. When the density of the rubber board increased, the insertion loss also increased. The 5–6 dB insertion loss difference was measured between the most and least dense rubber granule board baffles.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00112024-03-09T00:00:00.000+00:00MSW Management in Two Italian Mountainous Areashttps://sciendo.com/article/10.2478/rtuect-2024-0008<abstract> <title style='display:none'>Abstract</title> <p>Two case studies are reported in the present work. They regard municipal solid waste (MSW) management trends in the last decades in two Italian provinces selected to analyse some issues of waste management in mountainous areas. The first case study refers to a selective collection (SC) rate expected to reach 80 % soon. This scenario assumes SC mainly in kerbside mode. The scenario is based on specific local conditions: the absence of a thermo-chemical plant in the territory (but with a part of the residual MSW burnt in a neighbour province), the presence of local plant of anaerobic, and a sanitary landfill for pre-treated residual MSW. The adopted tariff helped increasing the SC rate: indeed, since 2013, a tariff calculated at user level, depending on the behaviour of each user, has been adopted. This is called punctual tariff. The second case study concerns an area where SC reached about 75 %. The punctual tariff has been recently introduced. In this scenario, an incineration plant and a Solid Recovered Fuel (SRF) plant allow implementing an industrial symbiosis solution in conjunction with a cement factory. The work demonstrates that SC can be the core of a correct MSW management and that kerbside collection is fully compatible with mountainous area. However, other issues remain to be optimized yet: the low density of mountain areas makes difficult to implement enhanced solutions of SC (e.g. for diapers) and increases costs for light packaging collection; moreover, the presence of tourist fluxes can significantly affect SC efficiency.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00082024-02-23T00:00:00.000+00:00Hydrothermal Conversion of Fly Ash into Monomineralic Zeolite Synthesis for Biodiesel Productionhttps://sciendo.com/article/10.2478/rtuect-2024-0009<abstract> <title style='display:none'>Abstract</title> <p>Fly ashes as a residue from combustion processes of coal in coal-fired power stations can be applied for zeolite formation. The zeolite synthesis has considerable effect on their structure following further catalytic use. The formation of analcime is guided by the operation of the silicate framework in the company of Na<sup>+</sup>, [Al(OH)4]<sup>−</sup>, [H2SiO4]<sup>2−</sup> species, coming from fly ash processing. Here, we have highlighted the importance of conducting the coal fly ash waste management towards monomineralic zeolite synthesis, in the form of powder analcime. It is the first report on powder analcime production without fly ash residues, confirmed by SEM and XRD analysis. The obtained analcime-zeolite was further explored as biodiesel catalyst based on base-catalyzed transesterification process. The effect of analcime catalyst usage on the biodiesel yield was determined with observed 97.2 % conversion efficiency under the concentration of 4%wt at 230 °C, with three times reusable analcime catalysts. Coal fly ash-derived monominerals on a large scale can significantly contribute to the sustainability goals and efficient waste management.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00092024-03-02T00:00:00.000+00:00Optimization Study of Carbon Emissions in Wind Power Integrated Systems Based on Optimal Dispatch Algorithmhttps://sciendo.com/article/10.2478/rtuect-2024-0010<abstract> <title style='display:none'>Abstract</title> <p>With the integration of wind power into the power system, dispatch becomes more complex and existing algorithms are no longer applicable. This paper focuses on optimizing carbon emissions in wind farm generation while considering issues related to wind power integration and carbon trading. An optimal dispatch algorithm was designed with the objective of minimizing total costs, which was then solved using the cuckoo search (CS) algorithm. Additionally, an adaptive improvement was made to the CS algorithm to obtain the improved cuckoo search (ICS) algorithm. An analysis was conducted on a case study with 10 units. The ICS algorithm obtained higher quality solutions, with a total cost of $ 632 719 and a calculation time of 0.51 minutes, which was superior to the solutions obtained by the particle swarm optimization and CS algorithms. Fluctuations in the confidence level of system rotation reserve capacity could lead to variations in the final system cost, which needs to be adjusted according to actual conditions. The dispatch scheme obtained by the ICS algorithm showed reduced carbon emissions, total costs, and better performance when compared with the optimal dispatch algorithm in different scenarios. The results show that the proposed methods are reliable and practical.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00102024-03-02T00:00:00.000+00:00Effects of Temperature, pH, and Agitation on Growth and Butanol Production of , , and https://sciendo.com/article/10.2478/rtuect-2024-0007<abstract> <title style='display:none'>Abstract</title> <p>Butanol is a promising alternative to fossil-derived fuels. <italic>Clostridium</italic> genus bacteria are known for their ability to produce butanol as one of the metabolites, however, at the moment this solution is not economically viable. To solve it, the process of butanol production should be optimized. While ABE fermentation has been extensively studied, information about the optimal growth conditions for specific microorganisms often differs from one study to another. Therefore, this study aims to search for optimal growth conditions in sealed serum bottle tests for three widely used strains in ABE fermentation. In this study effects of temperature, pH, and agitation were tested on <italic>Clostridium acetobutylicum</italic>, <italic>Clostridium beijerinckii</italic>, and <italic>Clostridium saccharoperbutylacetonicum</italic>. The optimal temperature for <italic>C. beijerinckii</italic> growth and butanol production was 32 °C, the optimal agitation speed for growth was 0 rpm, but for butanol production, it was 200 rpm. For <italic>C. saccharoperbutylacetonicum</italic> growth and butanol production pH 7.5, 30 °C temperature and an agitation rate of 100 rpm were optimal, however, this effect was slight. For <italic>C. acetobutylicum</italic> cultivation optimal temperature, pH, and agitation rate were respectively 37 °C, 6.5, and 200 rpm.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00072024-02-19T00:00:00.000+00:00Development of New Bio-Based Building Materials by Utilising Manufacturing Wastehttps://sciendo.com/article/10.2478/rtuect-2024-0006<abstract> <title style='display:none'>Abstract</title> <p>Over the last decade, research has increasingly focused on reducing the use of natural resources and improving waste management in the construction industry. Various possibilities exist for reducing waste in this sector, ranging from using waste as filler materials to developing new binders and building materials. This study focuses on the development of bio-based building materials using waste from the manufacturing of wood-wool cement boards. The binder and filler materials were obtained from the manufacturing waste and used in this research. The developed materials were tested for their visual appearance, macrostructure, material density, thermal conductivity coefficient and compressive strength. The results showed promising data for the self-bearing bio-based building materials, which had similar thermal properties to other bio-based materials and could be used as thermal insulation materials with a thermal conductivity coefficient of 0.0827–0.1172 W/(mK). The material density of the developed bio-based composites was found to be 430–617 kg/m<sup>3</sup>. By incorporating manufacturing waste into the production process of bio-based building materials, it becomes evident that overall waste from manufacturing plants can be significantly reduced, and the sustainability aspect of wood-cement board manufacturers can be enhanced.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00062024-02-12T00:00:00.000+00:00The Influence of Young People on Household Decisions on Energy Efficiency in Latviahttps://sciendo.com/article/10.2478/rtuect-2024-0005<abstract> <title style='display:none'>Abstract</title> <p>Young people are the future members of the energy communities, who play a role in shaping a climate-responsible society. However, in the context of the geopolitical and economic events of 2022, the awareness of young people in Latvia about energy efficiency issues and the readiness to engage in climate change mitigation processes, as well as the influence of their attitude on the decisions of adult household members in the field of energy efficiency have not been sufficiently studied. The issue is crucial within the framework of the European Green Deal, where various serious games for building energy communities are being developed, and young people are the ones who can influence the decision-making process. The purpose of the study is to provide serious game developers with an insight into young people's knowledge of energy efficiency issues, associations with a climate responsible society, attitudes towards daily habits in the field of energy efficiency, as well as whether climate change issues are discussed in families and whether young people believe that they can influence views and habits of their family members. 71 participants from four contrasting geographical regions in Latvia took part in the study. The study was conducted using qualitative research methods, including questionnaires and interviews. The results have shown that young people in the regions of Latvia are aware of energy efficiency measures, and the answers provide an insight into the various experiences they have had in their households. The research also highlighted negative aspects, such as young people’s unwillingness to strongly support household comfort level reduction in the name of climate change – only a little more than half would be willing to live in cooler rooms. Young people believe that they can influence the attitude and behaviour of other household members in an energy resource management matter. The results of the study lead to the conclusion that more attention should be paid to messages addressed to young people in public spaces, so that they associate themselves as an existing and future part of energy communities. They should be given examples and explanations regarding the importance of their actions in reducing climate change. Developers of serious games are encouraged to integrate aspects related to youth as participants in decision-making into the content of simulation tools, based on the results of the study.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00052024-02-12T00:00:00.000+00:00Analysing Metal Melting Methods for Green Transformation of Scrap Metal: Case Study of Latvia using MCDA and SWOT Analysishttps://sciendo.com/article/10.2478/rtuect-2024-0001<abstract> <title style='display:none'>Abstract</title> <p>Metal is one of the most widely used materials in the world. It was a crucial driving force in technological development since the industrial age and continues to push us forward to this day. As metal consumption grows, so does the amount of scrap metal generated. Proper utilization of this waste is crucial in mitigating the negative environmental impacts of the metalworking industry. The processing and use of raw materials is often associated with high resource consumption and high emissions. The utilisation of scrap metal instead of raw metal can lead to up to 10 times less electricity consumption and up to 30 times fewer CO<sub>2</sub> emissions. However, selecting the most suitable scrap metal processing technology is crucial, particularly in the case of the metal melting furnace which is the backbone of the industry. The efficiency of this process determines the environmental indicators for the entire scrap metal melting process. This paper conducts an analysis of 8 types of metal melting furnaces based on 11 environmental criteria. Furthermore, a SWOT analysis is conducted to evaluate the efficiency of the metal smelting process in Latvian metalworking enterprises and the potential for future expansion.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00012024-02-10T00:00:00.000+00:00Case Study of EPS Aggregate Insulation Material Used in Construction Siteshttps://sciendo.com/article/10.2478/rtuect-2024-0003<abstract> <title style='display:none'>Abstract</title> <p>Thermal insulation materials used in civil engineering have been developing throughout time. One of the latest thermal insulation used in construction sites with gained popularity is EPS aggregate and mineral binder-based composite. Waste recycling potential, low cost, and ease of installation have brought popularity to the material. This research investigates such material which is formulated by EPS aggregates and pure Portland cement binder thus making EPS aggregate concrete (EAC). Many contractors use such untested and uncertified EAC material due to the low cost of the raw materials. In this research, EAC was taken directly from the construction site. Material physical and mechanical properties are evaluated and compared to commercial counterparts. The drying of the material was investigated, following the practice in the construction sites where upper covering layers are built according to the time schedule ignoring material drying process. Results were compared with commercial EAC. Results indicate that rapid construction schedule with layer-to-layer covering of wet EAC results in dramatically slow drying of such composites, which is one of the main problems for safe use in civil engineering. EAC density from 113 to 169 kg/m<sup>3</sup> was measured with an average compressive strength of 49 kPa. The thermal conductivity of the tested EAC was from 0.050 to 0.055 W/(mK).</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00032024-02-10T00:00:00.000+00:00Supercritical CO Extraction of Fish Roehttps://sciendo.com/article/10.2478/rtuect-2024-0002<abstract> <title style='display:none'>Abstract</title> <p>Seafood is rich in omega-3 polyunsaturated fatty acids, and the good emulsifying properties of phospholipids make them suitable for use in the food, pharmaceutical and cosmetic industries. This study attempted to evaluate different fish species obtained using supercritical carbon dioxide without and with and ethanol as co-solvent extraction and organic solvent (ethanol) extraction. Supercritical CO<sub>2</sub> extraction was performed at 30–50 °C and at different pressures (17.7–33.0 MPa), maintaining a CO<sub>2</sub> flow rate of 0.6 mL/min for 3 hours. Gas chromatography and Bligh &amp; Dyer methods were used to analyze the extracts. The results showed that only one species of fish roe (rainbow trout) produced oil, but it was concluded that improvements were needed to be able to extract oil from African catfish roe using supercritical CO<sub>2</sub> extraction. Rainbow trout roe contains the most monounsaturated fatty acids (44 %).</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00022024-02-10T00:00:00.000+00:00Assessing the Sustainability Impact of Improving Secondary Steel Production: Lessons Learned from an Italian Planthttps://sciendo.com/article/10.2478/rtuect-2024-0004<abstract> <title style='display:none'>Abstract</title> <p>This work presents a sustainability assessment approach to evaluate technological innovations in secondary steel production making use of Electric Arc Furnace (EAF) technology. The assessment covers the environmental, social, and economic dimensions of sustainability by combining different tools (Life Cycle Assessment and Analytic Hierarchy Process), and also provides an integrated assessment of the overall sustainability. The approach, which can also be used to support decision-making, has been applied to a real case study of a steel plant located in Northern Italy. In the case study, environmental sustainability is positively impacted mainly by increased metal yield and reduced furnace energy consumption. The greatest social sustainability benefits are mainly related to improved ergonomic and safety conditions for workers (reduced demand for physical effort, manual handling and repetitiveness, and lower risk of accidents), as a consequence of the introduction of Industry 4.0 technologies. Regarding economic sustainability, a positive impact related to reduced cycle time, increased metal yield and quality yield, reduced maintenance and quality control costs was observed. The integrated assessment of the overall sustainability has proven to be a viable approach to manage trade-offs between the different dimensions of sustainability.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2024-00042024-02-10T00:00:00.000+00:00Microbial Carotenoids Production: Strains, Conditions, and Yield Affecting Factorshttps://sciendo.com/article/10.2478/rtuect-2023-0075<abstract> <title style='display:none'>Abstract</title> <p>The research and development of carotenoid production has a long history, and interest in this group of pigments has not decreased to this day. Six existing carotenoids are considered industrially important: astaxanthin, β-carotene, lutein, zeaxanthin, canthaxanthin, and lycopene. These carotenoids have a wide range of applications and are used as additives in food and beverages, feed, nutraceuticals, pharmaceuticals, and cosmetics products due to their bioactive and pigmentation properties. Currently, the global pigment market is dominated by chemically synthesized carotenoids. Carotenoids derived from natural sources such as plants and microorganisms are not as popular or widespread. Currently, the market of natural carotenoids is mainly represented by microalgae <italic>Haematococcus pluvialis, Dunaliella salina, Botryococcus braunii, fungus Blakeslea trispora</italic>, yeast <italic>Phaffia rhodozyma</italic> and bacteria <italic>Paracoccus carotinifaciens</italic>. These microorganisms produce astaxanthin, β-carotene, canthaxanthin, and lycopene. Several yeast and bacteria species from <italic>Rhodotorula</italic>, <italic>Sporobolomyces</italic>, <italic>Sporidiobolus</italic>, <italic>Gordonia</italic>, and <italic>Dietzia</italic> genus can potentially become sources of carotenoids on an industrial scale, but available technologies still need improving. This paper reviews strategies for increasing the competitiveness of fungal and bacterial carotenoid production. Strategies such as selecting carotenogenic strains, using low-cost substrates, stimulating the synthesis of carotenoids by adding trace elements, TCA intermediates, NaCl, H<sub>2</sub>O<sub>2</sub>, light irradiation, and optimization of fermentation conditions such as pH, temperature and aeration are considered.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2023-00752023-12-31T00:00:00.000+00:00Application of for Molasses Wastewater Decolourizationhttps://sciendo.com/article/10.2478/rtuect-2023-0077<abstract> <title style='display:none'>Abstract</title> <p>Molasses, a brownish black viscous liquid, is a byproduct of the cane sugar process. It finds applications in various industries such as fertilizer production, animal husbandry, alcohol production, monosodium glutamate production, and the production of acetic acid. In Thailand, it is primarily used for alcohol production and as animal feed. However, molasses wastewater is characterized by high levels of biochemical and chemical oxygen demand, as well as suspended solids. Untreated release of this wastewater into the environment can lead to numerous environmental issues. Additionally, the presence of melanoidins in molasses wastewater makes its removal challenging, resulting in a dark colour of the treated water. Discharge of this dark-coloured water into natural water sources can lead to an abnormal discolouration of the water. This study aims to investigate the optimal conditions for utilizing <italic>Citeromyces siamensis</italic> microorganisms in the biological treatment of molasses wastewater. The experiment was conducted to determine the conditions that facilitate the reduction of colour in molasses wastewater. The findings indicate that the addition of 1 % glucose and 1 % peptone was more effective in decolourizing molasses wastewater using <italic>Citeromyces siamensis</italic> compared to other nutrient additions. While the addition of additives may incur additional costs, it remains a more economical option compared to the use of chemicals for wastewater colour removal. Furthermore, the use of the additives is considered safe for living organisms.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2023-00772023-12-31T00:00:00.000+00:00Turning Trash into Treasure: The Use of Vulcanized Ash Filters and Glass Waste for Renewable Energyhttps://sciendo.com/article/10.2478/rtuect-2023-0076<abstract> <title style='display:none'>Abstract</title> <p>Biomethanation is a prospective method to integrate a renewable solar or wind power grid with a biogas grid, where excess energy can be used to produce hydrogen for the biomethanation of the biogas to produce biomethane. The use of biotrickling filter reactors with appropriate carrier materials for biomethanation is essential for the immobilisation of hydrogenotrophic methanogens on the surface of the packing material. This study tested the suitability of filter materials made from woodchip ash (FA and CA) and glass waste (GF) for methanogenesis in biotrickling filter reactors using comparative performance analysis. The readily available and widely used expanded clay pallets (EC) and polyurethane foam (PUF) in biomethanation were used for comparison. The manometric method and BMP test are used to determine the rate of CH4 production. CH4 produced using filter materials decreases in the order GF&gt;EC &gt;PUF&gt;FA&gt;CA, respectively. The physical parameters of tested materials are compared to other filter materials commonly used in biomethanation applications. Glass foam (GF) that is made from glass waste showed the best biomethane production rate of 201.2 NmL/Lmaterial, as it has the best physical properties for methanogenesis in biotrickling filter reactors such as low volume density, high external porosity, and neutral pH. Ash waste recycling is related to its specific chemical properties, as it is alkaline and contains heavy metals that can leach out and negatively affect living organisms.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2023-00762023-12-31T00:00:00.000+00:00Utilizing End-of-Life Tyre Crumb Rubber in Cement Formulation by Substituting Sand with Different Volume Proportionshttps://sciendo.com/article/10.2478/rtuect-2023-0074<abstract> <title style='display:none'>Abstract</title> <p>The number of end-of-life tyres recycled into crumb rubber varies widely across different countries and regions, depending on factors such as local regulations, infrastructure, and demand for the product. According to the International Rubber Study Group (IRSG), the global production of crumb rubber from end-of-life tires was estimated to be around 12.7 million metric tons. This study is devoted to the development of cement composites where the sand was partially and fully replaced with a specially prepared fine fraction of crumb rubber. Partial replacement of sand with crumb rubber changes the workability of the concrete. The lighter concrete composite may also have improved acoustic and thermal insulation properties. Complete substitution of sand with crumb rubber leads to a lighter concrete composite, featuring reduced densities and enhanced ductility. In these experiments, prisms of dimensions 40×40×160 mm were produced, with various mixes where we changed the amount of replaced sand with crumb rubber and water-cement ratios. These samples were tested for strength in flexure and compression, simultaneously producing force-deflection curves indicating that the rubber granules prevent brittle failure. By full sand replacement, a lightweight cementitious composite was obtained, with the potential for use as acoustic absorption materials and shock energy absorbing layers, but careful consideration of the specific application and mix design is necessary to ensure optimal performance and sustainability. Replacing sand entirely resulted in a lightweight cementitious composite, with densities of 2222 kg/m<sup>3</sup> for 10 % replacement and 1525 kg/m<sup>3</sup> for 100 % replacement by volume. This material holds promise for applications in acoustic absorption and shock energy absorption. However, achieving optimal performance and sustainability requires thoughtful consideration of the specific application and mix design.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2023-00742023-12-26T00:00:00.000+00:00Circular Economy: Origins, Evolution and Role of MSWhttps://sciendo.com/article/10.2478/rtuect-2023-0072<abstract> <title style='display:none'>Abstract</title> <p>Circular economy is presented today in opposition to linear economy. This last one was introduced at the end of the 19<sup>th</sup>, based on the terms: take, make, consume, through away. Its development was connected with the technological innovations for increasing the productivity as an absolute target. The analysis of the literature demonstrates that the first concepts of the material circularity were introduced before an official definition of waste, through the terms of Industrial Symbiosis and Industrial Ecology since the 40s. In the following decades important enhancements can be met in the criteria available for having an economy more oriented towards sustainability. A milestone can be considered the issue of the circular economy package from EU in 2015, specifically related to MSW, with the concepts of efficient and sustainable use of resources and new integrated model of production, distribution and consumption. As the EU decided to give centrality to MSW, this article analyses its role in the above-mentioned literature. CE and MSW were analysed also from another aspect: the generation of detailed information on the characteristics of residual MSW management is discussed as a strategy to support CE. Finally, the expectations of the sector as a consequence of the adoption of circularity concepts were analysed.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2023-00722023-12-26T00:00:00.000+00:00Cost-Optimal Policy Strategies for Reaching Energy Efficiency Targets and Carbon Neutralityhttps://sciendo.com/article/10.2478/rtuect-2023-0073<abstract> <title style='display:none'>Abstract</title> <p>The TIMES Latvia optimization model was developed to evaluate cost-effective pathways for reaching energy efficiency targets in 2030 and carbon neutrality in the Latvian economy by 2050. The model includes both the end-use sectors such as transport, buildings, industry and agriculture and the energy sector, with a well-developed database of existing and future RES and storage technologies. The modelling framework allows to identify the cost-optimal future energy mix by considering the electrification potential of each sector. Therefore, it allows the analysing of the impact of different policy strategies on sectoral integration levels and the necessity for additional energy storage capacities. The results show that one of the optimal solutions for reaching the energy efficiency targets in 2030 is the wide expansion of heat pump utilization merged with ambitious building renovation policy to increase energy efficiency. The building heat supply transformation also brings higher power consumption and interacts with the wider utilization of wind power. Alternative pathway could rely on increased solar power installation for self-consumption coverage which shows lower costs than building energy efficiency increase.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2023-00732023-12-26T00:00:00.000+00:00Extraction of Apple Pomace Using Supercritical CO Extractionhttps://sciendo.com/article/10.2478/rtuect-2023-0071<abstract> <title style='display:none'>Abstract</title> <p>Apple pomace, a by-product of apple juice and cider production, is a sustainable raw material from which valuable products such as nutritional supplements and pectin can be obtained. It contains significant amounts of antioxidant compounds that have been linked to several health benefits. Both traditional and new technologies can be used to extract valuable components from apple pomace, with an emphasis on new and environmentally friendly methods. One such technique is the use of supercritical CO<sub>2</sub> extraction. This method is considered environmentally friendly and can be used to extract valuable compounds such as antioxidants and pectin from apple pomace. This article examines the extraction parameters of apple pomace and analyzes the valuable substances in the extract samples. Apple pomace is a promising source of carbohydrates, proteins, amino acids, fatty acids, phenolic compounds, vitamins, and other compounds with a vast range of food applications.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2023-00712023-12-23T00:00:00.000+00:00Overview of Solar Photovoltaic Applications for District Heating and Coolinghttps://sciendo.com/article/10.2478/rtuect-2023-0070<abstract> <title style='display:none'>Abstract</title> <p>With the prevalent energy crisis and climate changes, decarbonising energy sector has become the need of the hour. An environmentally friendly way is the utilisation of solar energy which mainly involves the deployment of photovoltaic (PV) and/or solar thermal technology. Unlike electricity generation, the application of photovoltaics for the district heating &amp; cooling (DHC) is relatively new. Also, this energy route is yet to be fully explored. This paper aims to provide an overview of the photovoltaic applications in the context of DHC sector. At first, the utilisation of solar energy in the DHC sector is briefly described and then the review of the available literature is carried out. It was understood that PV integration in the district heating and/or district cooling system can take place in different topologies such as PV technology, energy storage, and system configuration (centralized/distributed). On one side, this technology options support design flexibility based on local scenarios (i.e., climatic conditions, building types, energy cost). On the other side, selecting the best configuration remains a challenging task for design and planning engineers. The research database on the studied topic needs to be enhanced, with a focus on PV’s role in district cooling (DC). It is deduced that right technical and economic boundary conditions in the chosen region is important for the accelerated photovoltaic integration. Also, lower environmental impact throughout the whole life cycle of solar PV integrated DHC system is reported. PV assisted DC systems have the potential to revolutionize cooling sector, especially in the places where daytime electricity costs are high. Based on the SWOT analysis, it is concluded that there is an enormous opportunity for PV integration in the DHC sector with the upgradations in DH networks, developing DC networks and rising adoption of HPs. This overview is expected to be beneficial to researchers, policymakers and other stakeholders of district energy sector.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/rtuect-2023-00702023-12-21T00:00:00.000+00:00en-us-1