The Scientific Journal of Riga Technical University
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Challenges in Standardizing Global Emission Factors for Peatlands
No full textPeatlands have a crucial role in the global carbon cycle, acting as significant carbon sinks, but become a significant source of greenhouse gas (GHG) emissions when peat extraction is taking place. This article presents a comprehensive overview of peatland ecosystems, emphasizing their classification across various climatic zones and the complex set of different characteristics that determine contribution to GHG emissions. Currently, inconsistency exists in definition of emission factors used between countries leading to varied approaches in estimating peatland emissions and posing significant challenges in the comparison and aggregation of global data on peat extraction related GHG. The aim of the study is to analyse the disparities in emission factors and calculation methodologies employed by different countries. Data from national GHG emission reports are submitted under the UNFCCC and the Kyoto Protocol. Emissions report data calculations and emission factors can be based either on nationally determined data or on data specified in the IPCC guidelines. Consequently, emission factor data for four countries - Latvia, Finland, Sweden and Germany - are collected and processed, which were compared with IPCC guideline data. The data were compared in two ways: by equating units of measurement and by modeling. The results show there is a pronounced difference between the emission factors of each country, however, all these factors are lower than the maximum values specified in the IPCC guidelines. It was also determined that comparing the total emission factors with the modeled results, no significant difference is observed between these results. The study concludes that emission factors are predetermined differently for each country, and it is not possible to specify the differences among assumptions for parameters included in the determination of the emission factors. The results suggest there is a need for development of more transparent accounting of emissions with regard to the diverse environmental and anthropogenic factors influencing peatland ecosystems. Factors like composition, depth of peat, water table levels, and local land-use practices further compound this variability in emission accounting. Addressing these challenges is crucial for enhancing the accuracy and reliability of GHG emission reporting under international frameworks like the United Nations Framework Convention on Climate Change and the Kyoto Protocol
Analysis of Introducing Plastic Waste Enzymatic Recycling for Sustainable Waste Management in Latvia
No full textEconomic growth, urbanisation, and consumer consumption habits have contributed to the yearly increase in the municipal solid waste amount. A significant portion of household waste consists of plastic materials and packaging, which currently cannot be fully and endlessly recycled, does not decompose in nature, and degrades into micro- and nanoparticles entering the soil, air, aquatic environments, and organisms. According to an OECD report from 2022, the amount of plastic waste produced globally is expected to triple by 2060, with around half being landfilled and less than one-fifth being recycled. As waste volumes are going to increase, the need to ensure appropriate waste recycling technology is addressed in this study by introducing enzymatic plastic waste recycling in Latvia. Enzymatic recycling has an advantage over mechanical recycling technology because it can depolymerise plastics without degrading the quality of the material. The methodology applied in this study includes data analysis of the waste amount in Latvia, analysis of the existing plastic recycling plant operation, life cycle assessment of existing and proposed methods, and socio-economic impact evaluation. The proposed solution meets the objectives of promoting sustainable plastic waste recycling through the introduction of enzymatic recycling; therefore, it aligns with the European Union’s targets to follow circular economy principles
Rīgas Politehnikuma / Rīgas Politehniskā institūta profesora Heinriha Malhera (1848–1927) darbība un devums Latvijai
No full textRīgas Politehnikumā (RP) tā pastāvēšanas pirmajās desmitgadēs strādāja daudz ārzemnieku, viņu vidū arī viens no starptautiski atpazīstamākajiem docētājiem un zinātniekiem ģeodēzists un hidrotehniķis Heinrihs Malhers (Heinrich Malcher; 1848–1927), kurš turpināja strādāt arī pēc augstskolas reorganizācijas par Rīgas Politehnisko institūtu (RPI; 1896). 20 gadu profesors bija RP / RPI Inženieru nodaļas vadītājs (1882–1902). Līdzās pedagoģiskajam darbam H. Malhers izprojektēja ūdensvadu Jelgavai (1881), vadīja Rīgas pilsētas pirmā triangulācijas tīkla izveidi, nodarbojās ar pilsētas notekūdeņu novadīšanas jautājumiem, darbojās Rīgas Tehniskajā biedrībā. Mūža nogalē viņš dzīvoja Čehijā, Kujavī ciematā, kur izveidoja pirmo ūdens sadales sistēmu un strādāja par celtniecības konsultantu un inspektoru
Editorial Introduction to Issue 39: Managing Complexity and Knowledge in Enterprise Projects
No full textThis issue of CSIMQ includes five articles selected on the topics of complexity management and knowledge management in enterprises from various perspectives and towards diverse goals: the economic and societal perspective seeking strategy fulfillment with the help of enterprise architecture management, the operational performance perspective, which requires grounding management decisions on data insights, and the human aspect perspective to facilitate collaboration, creativity and innovation. Methodologically, the issue reports a mix of conceptual modeling and analytics approaches, suggesting an emerging requirement to balance or alternate, in complexity management, abstraction-based analysis, and data-oriented analytics
Optimisation of the Production of Bio-Based Basic Chemicals from Biogenic Secondary Waste Through Dispersion
No full textBiogenic waste from waste treatment plants, also known as secondary waste, can be used to produce bio-based carboxylic acids. Conventionally, these are produced by chemically synthesis of petroleum-based raw materials or synthesis of natural oils (e.g. coconut or palm kernel oil). Using organic residues and waste materials in a cascade to produce bio-based products can contribute to the circular bioeconomy. In the biological treatment process for production of bio-based carboxylic acids, microorganisms that are already present in the secondary waste use ethanol to convert short-chain carboxylic acids (with one to three carbon atoms) into medium-chain carboxylic acids (with four to ten carbon atoms). During the treatment process, medium-chain carboxylic acids are separated from the secondary waste by using in-situ extraction (liquid-liquid extraction). In previous studies, bioreactors without a dispersing function were used on a laboratory scale. In order to optimise the production and extraction of the formed medium-chain carboxylic acids, the bioreactors should be upgraded with a device for dispersing the extraction solvent in the secondary waste. Dispersing can increase the surface area between the extraction solvent and the secondary waste and therefore also the ability to extract the medium-chain carboxylic acids. To evaluate the effects of dispersing on the production of bio-based carboxylic acids, the production and extraction rates of static bioreactors without dispersing are compared with those of dynamic bioreactors with dispersing on a laboratory scale. Leachate from a composting plant was used as secondary waste. According to the results of the current study, it can be confirmed that dispersion has a positive effect on the biological treatment process. In addition to the increased degradation of the nutrient ethanol, the production of medium-chain carboxylic acids in the secondary waste as well as the extracted medium-chain carboxylic acids could be increased by dispersing
Safe Insulation from the Inside as a Solution to the Energy and Climate Crisis
No full textAlong with rapid climate changes, issues related to energy efficiency and efficient use of energy are becoming more and more relevant in the EU. One of the energy-consuming sectors is buildings, which are responsible for about 40% of the EU final energy consumption and 36% of CO2 emissions. In addition to this, the current energy crisis has acutely raised the issue of energy poverty. Therefore, one of the ways to fight with energy poverty and high energy consumption in buildings is insulation from the inside. However, warming from the inside is risky due to hygrothermal processes and mold risks. This study assesses the hygrothermal performance of masonry walls with 9 interior insulation systems exposed to different external conditions in the climate chambers. Masonry walls were tested in a steady cycle, a dynamic cycle, a dynamic cycle with rain and a steady cycle as drying. Also, an identical simulation of the hygrothermal process was carried out in the DELPHIN software to compare results of both testing methods. Both vapor-open and vaportight systems were chosen as insulation systems. Results show that the hygrothermal behavior of vapor-open and vapor-tight insulation systems are different under different test cycles regarding different vapor diffusion resistance of materials. Mathematical simulations results are different from the climate chamber simulations, because of the change in material humidity, that are changing during climate chambers simulations. From this it can be concluded that mathematical simulations do not give a complete vision of hydrothermal processes, because they are dynamic, but in modeling the properties of materials are defined. The study provides valuable data on hygrothermal processes in different wall insulation systems from the inside
Exploring the Potential of Renewable Energy to Enable Green Hydrogen Production for a Sustainable Future
No full textAbstract – Amidst intensifying concerns about greenhouse gas emissions, the imperative to transition towards sustainable energy solutions is paramount. Renewable energy sources (RES) provide a promising avenue, especially in hydrogen production. In this context, the emergence of “green hydrogen” is pivotal. Green hydrogen is a concept produced using RES like solar and wind energy to power the hydrogen production process. Unlike conventional methods emitting carbon dioxide, green hydrogen is generated through water electrolysis using clean energy. India relies on coal for around 70% of its energy needs, leading to a 29% rise in carbon emissions from 2015 to 2022. Green hydrogen is a potential alternative solution to address the increasing energy demand and the depletion of fossil fuels. Using wind energy for water electrolysis emerges as a suitable method for green hydrogen production. Therefore, in the present study, assessed the potential of hydrogen production using the wind energy resources in five selected locations in India using ERA5 hourly wind data. The investigation further explored the characteristics of wind speeds at these locations using average wind speed, Weibull parameters and wind rose analysis. Using the SUZLON S95 wind turbine, power output and annual energy generation at each location were estimated. Further, estimated the annual hydrogen production and required storage capacity at each location. The results showed a power generation of 891 kW in location Una and 895 kW in Mandvi. Finally, the amount of carbon emissions mitigated due to the use of wind energy sources instead of conventional sources for H2 production is calculated
Assessing Environmental Impact: Organosolv Extraction of Cellulose Pulp from Wood Waste
No full textIn the upcoming years, the paper industry is expected rely on containerboard for packaging, with approximately 80% of it being made from recycled fibers by 2020. Creating a new supply chain for fibers could help mitigate possible shortages. In this context, wood waste emerges as a valuable resource with the potential to serve as a plentiful and cost-effective reservoir for generating new materials, as cellulose fibers. This study presents an assessment of the environmental impact associated with the organosolv extraction of cellulose pulp from wood waste based on a previous in lab study conducted by the authors. The increasing demand for sustainable materials has prompted exploration into alternative methods for cellulose pulp production, with a focus on minimizing environmental footprint. Organosolv extraction, a promising technique, involves the use of organic solvents and acid catalysts to break down lignocellulosic biomass, resulting in high-quality cellulose pulp production. To evaluate the environmental implications of this process, a comprehensive life cycle assessment (LCA) approach was adopted. The LCA framework considers all stages of the organosolv extraction process, from wood waste collection to cellulose pulp manufacture, using a gate-to-gate approach. The functional unit for assessment is set as one ton of cellulose pulp. The dataset utilized for the LCA comprises primary data obtained from laboratory experiments, complemented by secondary data sourced from literature and the Ecoinvent life cycle inventory database. Furthermore, sensitivity analysis was conducted to assess the influence of key parameters on the environmental performance of the organosolv extraction process, with a focus on variations in energy consumption to identify potential areas for optimization and improvement. In summary, this study emphasizes the environmental aspects of utilizing organosolv extraction for cellulose pulp production from wood waste. Further research is warranted to explore energy consumption during the organosolv process for obtaining more precise data and optimizing the process. This could be achieved through pilot-scale experiments or utilizing process simulation software
Integrating Sustainable Energy Technologies into District Cooling Systems: A Review of Modelling and Optimisation Approaches
No full textWith the rising cooling demand and prevalent energy crisis, District cooling (DC) is evolving as one of the sustainable energy solution worldwide. As per ‘EHP DHC Outlook, May 2023’, the sales in DC sector reached 3 TWh, covering more than 150 European cities. The centralised nature of the DC system offer benefits such as energy efficient operations, sector coupling, peak load management. Further, the feasibility of integrating renewable technologies (eg. solar energy), free cooling sources (eg. seawater heatpumps) and thermal energy storage (eg. ice slurry) is also explored. These developments make the futuristic DC system quite complex, as it involves multiple energy transformations. In this regard, utilising computation tools for decision-making has become increasingly relevant. However, choosing the appropriate approach among the existing ones in this evolving field is a curb some task for energy practitioners. The aim of the study is to review the modelling and optimisation approaches in the context of innovative DC systems. Data collection and analysis is based on desk-review of scientific literature published in the recent past. Firstly, various possibilities of integrating sustainable energy technologies for DC applications are explored. Then, relevant modelling and simulation approaches are studied, focussing on the similarities and limitations. Finally, different optimisation methods are examined in terms of parameters such as objective functions, control variables, solving techniques. The contribution of the study involve overview of different integration pathways, identifying the strength and weakness of modelling approaches and insights into suitability of optimisation techniques. It is expected that this study will be a reference material, while performing feasibility studies as well as developing digital-twins in DC context
Adaptive Building Envelope Structures
No full textClimate changes which are increasing year by year are impacting not our environment but also our daily lives. One of the problems is the emission of greenhouse gases which are produced by householdings using heating fuel. Buildings in the Europe Union represents for 40% of energy consumption and 36% of greenhouse gas emissions. It’s very necessary to think about how to reduce consumption of energy and emissions. To design a strong building nowadays is very difficult and complex task, due to a growing to fulfil sustainability in the built environment, societal and economic performance requirements. Technologies, methods, and technical solutions are changing in building construction. More and more we have passive, active or net-zero buildings, and it’s the first step to reduce emissions in householding sector. Moving forward, adaptive building envelope structures which incorporates using biomimicry principles, are the next step to find solutions how to save energy and consumptions. Biomimicry teaches a way how to find and integrate the processes from nature and use them in research and design. The main goal is to identify physical characteristics of animal thermoregulation strategies such as fur, fats, vasoconstriction, and work harmony with the nature. For better results, it is important to collect all data, systemize, filter, and arrange it to create a database with the nature properties and technical information. After that the results shows the potential of a new adaptive building envelope structure database which can be used by environmental specialists, also other engineers as well as architects and civil engineers