The Scientific Journal of Riga Technical University
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Future of District Heating Systems – Investigation of Various Technologies in Danish Context
No full textIn response to the urgent need for decarbonization, district heating (DH) systems must explore emission-reducing investments that simultaneously lower operational costs of the plant. The recent years with wildly fluctuating gas and electricity prices put even more emphasis on finding the optimal combination of generation units for DH systems. This article aims at investigating which of the available technologies are the future of district heating. Solar collectors, photovoltaics (PV) and wind turbines and their combinations with other technologies are considered. The analysis is done based on Assens District Heating located in Funen, Denmark, where the annual heat production is approximately 96 000 MWh. The plant has already invested in an East-West oriented PV plant and a heat pump. However, for the purpose of this paper, an assumption is made that this investment can be redone based on the present investment costs in Denmark. The analysis is made in the energy system analysis tool energyPRO, where different combinations of technologies are analyzed. The study investigates the operational and investments costs, looking into the influence on Net Heat Production Cost (NHPC) and quantifying the investment yearly benefit. The results demonstrate profitability and feasibility of integrating renewable energy resources into district heating systems within the Danish context. The ambition is to showcase the possibilities and provide decision makers with insight into robust investments in renewable energy systems. Furthermore, by highlighting the success and potential of renewable energy integration in district heating systems in Denmark, this study aims to inspire further research and innovation in the field in other European countries, where the DH systems are primarily based on fossil fuels
Replacing Traditional Materials with More Sustainable Ones: The Use of Arundo Donax, L. As Bio-Building Material and Pellet
No full textConsidering the hazardous future scenarios outlined for the environment by the scientific community and various institutions, embracing more sustainable production methodologies is imperative. This is especially vital within the construction and energy sectors, which stand as significant contributors to climate change and environmental impact. The topic presented herein aligns with this direction. Specifically, the aim of this study is to highlight the benefits of transforming conventional agriculture into a technologically advanced and environmentally sustainable practice. The proposed study demonstrates new ways of using reeds (Arundo Donax, L.) in two strategic sectors - i.e., building and heating fuel - promoting the reduction of environmental impacts compared to traditional materials. The study explored the utilization of reeds as a material for roofing or wall coverings and as pellets for heating stoves. A Life Cycle Assessment was performed to investigate environmental impacts in all the phases of the processes. In the first case (i.e., reeds used in the building sector), a reduction of environmental impacts within the construction phase was found, followed by an enhancement of performance in the buildings on which the reed panels were installed. In fact, they contribute to minimizing heat losses, leading to a subsequent decrease in fuel consumption for heating and cooling, and help to mitigate acoustic problems. In the second scenario (i.e., reeds used as heating fuel), the goal of the study was to detect if Arundo Donax was suitable for pellet production. In this instance, all the production processes were analyzed (e.g., harvesting, shredding, drying, pelletizing) together with the intrinsic characteristics of the pellets (e.g., calorific power, content of carbon, etc.). This analysis enabled the evaluation of substituting traditional materials with reeds
CONECT 2023 XVI International Scientific Conference of Environmental and Climate Technologies
Get PDF10–12 May 2023 | Riga, Latvi
A Sustainability-based Approach for Geotechnical Infrastructure
Get PDFUrban growth needs large cities, and the current emphasis on landscape preservation makes using underground spaces both an opportunity and a significant necessity. However, underground construction techniques significantly impact the sustainability of the built environment, including infrastructure systems and their entire supply chains. Nowadays, there is a shortage of quantitative methodologies to assess and measure the sustainability of underground building processes that effectively integrate the three pillars of sustainability (environmental, social, and economic). Thus, this study aims to solve the abovementioned issues by explaining how to incorporate sustainability goals into geotechnical projects to address measure-driven strategies and eco-design-based solutions appropriately. This study illustrates a novel methodology based on the Life Cycle Thinking approach, with a particular emphasis on geotechnical ground improvement techniques. Specifically, the suggested method incorporates the concept of the EU Taxonomy, following the EU Green Deal, with the Envision framework to guide decision-makers toward a more sustainable, resilient, and equitable infrastructure design. In addition, incorporating a cradleto-grave Life Cycle Assessment (LCA) into the suggested methodological approach will improve the quantitative estimation of the performance of construction processes. The definition of the proposed method will provide the guidelines to systematically assess the sustainability of geotechnical infrastructures to allow further the selection of an optimal solution to reduce their impact from an environmental, social, and economic point of view
Numerical Model and System for Prediction and Reduction of Indoor COVID-19 Infection Risk
Get PDFAirborne aerosol transmission is a significant route of SARS-CoV-2 and other viruses in indoor environments. The developed numerical model assesses the risk of a COVID-19 infection in a room based on the measurements of temperature, relative humidity, CO2 and particle concentration, as well as the number of people and occurrences of speech, coughing, and sneezing obtained through a dedicated low-cost sensor system [1]. As the model operates faster than real-time, it can dynamically feed this information back to the measurement system or building management system, and it can activate an air purifier with filtration and UV-C disinfection when the predicted infection risk is high. This solution enhances energy efficiency as (1) lower ventilation intensity is necessary in the cold season to reach the same safety level and (2) the purifier is activated only if the predicted infection risk is above a certain threshold.The model is integral and takes into account the average values of simulated variables. However, it considers the inhomogeneous vertical distribution of concentration of droplets and aerosol particles. The droplets expelled by a potentially infectious person at a certain height through breathing, speaking, coughing, and sneezing are characterized by the total amount of expelled liquid, droplet size distribution and virus particle concentration. The rate of droplet evaporation depends on the temperature and relative humidity. Droplets are redistributed within the room vertically through turbulent diffusion and gravitational force. If the final droplet diameter is less than 5 mm, these particles are considered airborne and can leave the room only by ventilation, filtration, or by sedimentation on surfaces through Brownian diffusion. As a person in the room inhales these droplets and aerosols, the risk of infection increases as the number of absorbed virions grows, with the probability of infection being 50% when 300 virions have been inhaled.The parameter studies using the model indicate that the coughing and sneezing events greatly increase the probability of infection in the room, therefore the identification of these events is crucial for the applied measurement system. A method for determining the unknown ventilation intensity by measuring the number of people and the CO2 concentration is proposed and tested
KxKali v0.1: A Work-in-Progress Tool for Streamlining Thermal Comfort Evaluation in Building Design and Occupancy
Get PDFThermal comfort evaluation is crucial in the design of buildings, as it impacts the well-being and productivity of building occupants. Many national regulations and international standards provide guidelines for assessing thermal comfort. In order to simplify this process, we have developed a program called KxKali, which is intended to evaluate thermal comfort based on temperature and relative humidity data input using the adaptative comfort model of EN 16798. The current version of the software, v0.1, is only able to accept data from computer simulation using the official Spanish simulation software HULC and performs graphing and counting automatically, without the need for the user to edit, modify or handle any data manually. By using HULC as the source of input data, the tool can take advantage of the software’s established reputation and acceptance among professionals in the building design industry in Spain, streamlining the comfort evaluation process by eliminating the need to generate input data manually, or using additional software. However, future versions are planned to accept data from other software and also monitored data. In addition, there are plans to implement the evaluation of thermal comfort following other regulations. The ultimate goal of this project is to convert KxKali into a user-friendly and widely accessible web-app that professionals can use in the design phase without performing any additional work apart from what they are already doing for energetic certification, which may improve building design by allowing architects and engineers to quickly evaluate different thermal comfort scenarios and optimize their design for comfort, and also facilitate the process of post-occupancy evaluations (POE). The goal of this presentation is to show the current capabilities of the KxKali tool, and to obtain feedback from other specialists on how to improve it and make it more widely useful. In the paper, the limitations of using simulation data from HULC and the ongoing developments of KxKali such as accepting monitoring data and converting it into a web-app will be discussed. Additionally, the paper will showcase mockups of the future web-app version of the tool, providing a glimpse into its intended user interface, and the expected reporting and output
Sustainable Technology of Wood Charcoal Diffuser for Indoor Acoustical Quality
Get PDFWood charcoal is sustainable, renewable, environmentally friendly material using which the acoustic device may be produced. Charcoal made of wood waste materials allows to improve indoor acoustical quality. The current article aims to investigate sound scattering coefficients of quadratic residue diffusers with the covering of oak (Quercus robur) wood charcoal elements. The sound scattering coefficient is calculated due to the reverberation time measurement in the reverberation chamber. The calculation results of the scattering coefficient show the growth of scattering in the frequencies – the highest value reached 0.88 (diffuser N7 with charcoal). The effectiveness of diffusers to diffuse sound waves increases as the number of wells grows. The diffuser with 80 % charcoal elements showed a higher scattering coefficient comparing to the diffuser without charcoal elements
Accelerating Microorganism Strain Selection for Enhanced Productivity: A Review of Microdroplet Technology Solutions for Screening Mutant and GMO Strains
Get PDFThis article reviews state-of-the-art microdroplet technological solutions for screening microorganisms mutant and GMO strains. Microorganisms used in the production of various products – single-cell protein, single-cell oil, enzymes, pigments and other bioactive compounds – can always be improved and their properties enhanced to increase the production of products of interest, to simplify microbial cultivation process, improve efficiency or adapted strains to use cheaper raw materials such as agroindustrial by-products. Microorganisms can be improved using either classical mutagenesis techniques or genetic engineering methods. Regardless of the selected method for mutant or GMO creation, during the process most promising microorganism strains must be selected, which is usually a slow and labour-intensive process. The use of microdroplets is a promising technological solution to speed up strain selection. This review looks at the latest developments in microdroplet technology, compares their variations, and identifies future prospects
Impact Assessment of Steel Circularity Scenarios: Case Study of Steel Radiator based on Life Cycle Assessment (LCA) Methodology
Get PDFSteel is one of the most used materials in the industry and the building sector. Its production causes severe environmental impacts due to direct emissions within extraction and processing stages (e.g. CO, SOx, NOx, and PM2), the intensive use of primary resources, contamination of wastewater, and significant amounts of hazardous and solid waste. In this context, the purpose of the current study is to perform a life cycle analysis (LCA) of four different types of steel used in the manufacturing of a steel-based radiator, namely: standard steel as a baseline scenario, steel with a recycling fraction of 40 % of scrap, steel with a recycling fraction of 60 % of scrap, fully recycled steel from scraps, and a hypothetical ‘Carbon-free’ steel production process. The baseline scenario relies on data from an existing company producing steel radiators. The LCA study is conducted within SimaPro 9.4 software with data obtained from the Ecoinvent 3.8 database and adjusted according to the defined scenarios and the functional unit of ‘1 kg of steel’. The environmental impact is assessed according to EN 15804 requirements for construction product sustainability. The results have shown that standard steel has the highest impact (176.87 μPt), followed by 40 % scrap steel (137.46 μPt), 60 % scrap steel (104.36 μPt), ‘carbon-free’ steel (76.14 μPt), and 100 % scrap steel (38.17 μPt). The climate change indicator is found to be one of the most sensitive for steel production. The selection of ‘carbon-free’ or 100 % scrap steel permits a decrease of impacts by 70 % and 84 %, respectively. The study concludes that the choice of steel is a fundamental point in reducing the environmental impact of construction products such as steel-made radiators within the whole life cycle perspective. Furthermore, the results obtained through the EN 15804 method, tailored explicitly for the Environmental Product Declaration (EPD), can be reused or taken as a starting point for further studies in the environmental labelling sector
Life Cycle Assessment of Black Soldier Fly, Yellow Mealworm and Soybean Protein for Use in Fish Feed
Get PDFAs the consumption of fish in the human diet increases, a larger amount of production is needed. The growing demand for fish also has an impact on fish feed, its production efficiency and the sustainability of using raw materials. To evaluate the sustainability of raw materials and the impact on the environment, three protein alternatives are compared – black soldier fly, yellow mealworm and soybean. Each alternative has advantages and disadvantages. The advantages of black soldier fly and yellow mealworm are a valuable source of protein, sustainable growth (as feed can be used for food waste) and no need for arable land. Disadvantages of black soldier fly and yellow mealworm are price, an unbalanced diet can negatively affect growth, and nutritional value effect on the fish vary depending on fly or mealworm species. The advantages of soybeans are price, availability and high protein content, but the disadvantages are a lack of essential amino acids that affect the quality of fish and poor palatability. An LCA study has been carried out for the black soldier fly, yellow mealworm and soybean protein. From PEFCR most relevant impact categories are climate change, particulate matter, acidification, land use, eutrophication terrestrial and water use. The total single score value for black soldier fly protein is 1.43E+01 μPt, for yellow mealworm protein is 3.89E+02 μPt and for soybean protein is 9.72E+01 μPt. Large impact is from electricity consumption, used components for feed. Sensitivity analysis was performed for black soldier fly protein and yellow mealworm protein production, where feed composition was changed. In sensitivity analysis environmental impact is less from the new feed structure. The reason might be that the new feed structure has used food waste and wheat as feed ingredients