The Scientific Journal of Riga Technical University
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Biodiesel with Fuel Additive: An Analysis of Engine Performance, Combustion and Emission Characteristics
Full text linkThreats to the environment from exhaust emissions and global warming continue to generate more calls by most governments to end the use of fossil fuels and switch to green fuels. This study aims to examine one of the green fuels that is seeing rapid expansion, namely the biofuel known as biodiesel. Biodiesel is non-toxic, biodegradable, made from renewable sources and can reduce diesel engine exhaust emissions. Even though one of the technical benefits of biodiesel is its ability to be oxygenated in diesel engines without much hardware modifications; however, it has been unable to reduce exhaust tail emissions from diesel engines on its own. In this research, the impact of biodiesel mixed with oxygenated additive, diethyl ether, when subjected to performance, combustion, and emission tests in unmodified diesel engine at different speeds has been studied. Waste cooking oil was transesterified using methanol as a reagent and NaOH as catalyst. The biodiesel was blended manually at room temperature with diesel fuel and diethyl ether in different proportions while keeping the volume of diethyl ether constant at 10 %. The fuel blends (B10D90, B20D80, B30D70, B10A10D80, B20A10D70, and B30A10D60) were subjected to performance, combustion, and emission tests in a single-cylinder, four-stroke diesel engine coupled to a water-cooled Eddy current dynamometer and results obtained compared with diesel fuel. The results showed that all performance characteristics (brake power (BP), brake torque (BT), brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC)) improved with B10A10, which was found to closely resemble diesel. The peak cylinder pressures were higher for the blends, while the cylinder temperatures were comparable to those of diesel. The carbon monoxide (CO), carbon dioxide (CO2), hydrocarbon (HC) and oxides of nitrogen (NOx) emissions decreased more for all tested blends than for those of diesel at all engine speeds. Adding diethyl ether additives improved the physicochemical properties of biodiesel, making it a viable method for using biodiesel efficiently in diesel engines without modifying the engine. The study found that using green diesel fuel with a diethyl ether additive is a potential step toward improving air quality by lowering emissions from stationary, and transportation engines while maintaining optimal engine performance. As a result, using biodiesel-diesel fuels with the appropriate proportions of diethyl either additive has the potential to reduce greenhouse gas (GHG) emissions and ensure benign environment
The Comparison of RES Sustainable Development in the Main Sectors of Economy
Full text linkEnergy consumption in different sectors is responsible for more than 75 % of total EU greenhouse gas emissions. Energy is a priority when it comes to achieving climate goals and keeping greenhouse gas emissions low. The Green Deal is based on the need to use renewable energy sources in the energy sector while ensuring the replacement of fossil fuels and reducing energy dependence. The comparison of sustainable development trends in renewable energy sources (RES) is carried out for all sectors analysed in the study, such as industry, services, agriculture, transport and households. The aim of the study is to find out which of the types of RES is the most promising and sustainable in each sector and which factors influence this the most. The study develops a model that combines both qualitative and quantitative research methods to obtain the most objective and descriptive results possible on RES technologies in different sectors of the economy. In addition to a separate comparison of RES types by sector, a joint sectoral comparison was also made to evaluate the differences in development trends between the sectors considered. The highest rating level for sustainable development was achieved by the potential of biomass use in the agriculture and transport sectors. According to the obtained results, both solar energy and biomass have a high development potential in all analysed sectors, which is also reflected in the higher average values of the overall results
Use of Synthetic Fuels Derived from Green Hydrogen and CO2 in Heavy-duty and Long-range Transport: the Case of Latvia
Full text linkDecarbonization of the transport sector may be more challenging than it is for the power supply and heating sectors. Green hydrogen, i.e., produced from renewable energy sources, combined with CO2 captured from flue gases or air can be used to produce synthetic fuels, e.g., dimethyl ether (DME), ammonia, and jet fuel. These synthetic fuels can be used in heavy-duty and long-range transport, i.e., trucks, ships, and airplanes. The research question of this study is: how much green hydrogen and CO2 is needed to replace fossil fuel in the mentioned transport sectors with synthetic fuels? How much of the power demand for production of the synthetic fuels can be supplied from renewables, i.e., wind and solar power, considering the installed capacities of these technologies, and the excess power that can be used for the hydrolysis process. The case of Latvia for the year 2050 is used for the simulation of scenarios with various mixes of renewable power production. The simulation is done on an hourly basis for the whole year, using EnergyPLAN software as the modeling tool. The results show the total hydrogen and CO2 demand, the total power demand for hydrolysis of green hydrogen, and the share of the demand that can be covered by renewable power technologies. The results also include the costs of synthetic fuel supply for the considered transport sector. The results are obtained for scenarios of different combinations of installed capacities of wind power plants and solar PVs
LCA Sensitivity Analysis of an Energy-Biochar Chain from an Italian Gasification Plant: Environmental Trade-offs Assessment
Full text linkDue to its potential applications in bioenergy production, coproducts (bio-oil and syngas), mitigation of global warming, sustainable agriculture, pollutant removal, and other uses, biochar has drawn interest from all over the world. Producing and using soil-based biochar as a method of carbon sequestration could help reduce emissions while benefiting the soil and opening up possibilities for bioenergy production. However, to characterize the production cycle’s environmental and energy loads and confirm all of the advantages of biochar, Life Cycle Assessment (LCA) represents a reliable tool for evaluation. This work is based on continuing the study of Marzeddu and Cappelli (Marzeddu, Cappelli, et al., 2021) to understand the environmental impact of an energy-biochar chain involving a gasification plant in Italy. In the LCA carried out in the previous paper for the characterization of biochar, which is used as a soil conditioner, soil carbon sequestration, nitrous oxide emissions, fertilizer use, and water use for irrigation were considered. The results showed that the use of gasification for energy and biochar is an attractive strategy for mitigating the environmental impact analysis, especially climate change, with a net decrease of about ‒8.3·103 kg CO2, eq. The previous study was lacking a sensitivity analysis. For this reason, a sensitivity analysis is proposed in this study to consistently assess the environmental trade-offs of the biochar and the amended soil. In specific for the upstream processes the sensitivity is addressed to the selection of a different type of woodchips, for the core process in terms of selection of different packing material, and to the entire cradle-to-grave perspective by improving the logistics of the transportation, the distances within the supply chain and the choice of BAT technology for the transportation vehicles. This study highlights strategic research developments that combine to find potential environmental trade-offs and thresholds towards using biochar and its final use as a soil conditioner
Prediction of CO2 Emissions Using Machine Learning
Full text linkCarbon dioxide (CO2) is one of the important issues concerning human evolution that drives global climate change. It is emitted from the combustion of fuels causing global warming. The global community has gradually turned to pay more attention to environmental issues. This paper implements four prediction models using Multiple Linear Regression (MLR), Support Vector Machine (SVM), Random Forest (RF) and Convolutional Neural Network (CNN, or ConvNet) to predict CO2 trapping efficiency among CO2 emissions, energy use, and GDP. The Machine Learning (ML) approaches used in this study have shown good performance with SVM and CNN models with MAPE. The result can be a significant model for the decision support system to improve a suitable policy for global CO2 emission reduction
Mapping of the Bioeconomy Ecosystem in Latvia
Full text linkBioeconomy is no longer limited to being a concept in research papers and policy strategies; it presents real opportunities for regional development, i.e., by improving local employment, socio-economic development, economy and sustainable local bioresource use. But the obtaining of these opportunities is challenged by various barriers. It is proposed that analogously with other widely research fields (energy efficiency, industrial sustainability), the implementation of novel bioeconomy ideas, even when they are scientifically based, encounters the so-called ‘implementation gap’ (similarly to, e.g., the ‘energy efficiency gap’). This implementation gap is related to national, but also regional challenges, i.e., technical, economic, organizational, behavior and other barriers that hinder the most successful bioeconomy deployment. The technical obstacles can be, e.g., lack of processing or production technologies, capacity problems, while organizational barriers can manifest as logistics chain problems due to the availability of bioresources or internal organization problems of the company, lack of time, reluctance to take on new responsibilities or lack of awareness of opportunities provided by the bioeconomy. This significance of the regional analysis level for barrier assessment calls for more precise information. The first step for in-depth investigation of the bioeconomy implementation gap in Latvian context is the research of the bioeconomy ecosystem. In fact, as required by the National industrial policy guidelines, the Strategy for knowledge based bioeconomy development for Latvia was developed in 2022 by the Latvian bioeconomy ecosystem stakeholders. The current research focuses on the identification and more detailed characterization of the stakeholders of Latvian bioeconomy ecosystem, their interactions, as well as the identification of current challenges and barriers for knowledge-based bioeconomy and innovations development. In order to further elaborate the structure of the bioeconomy ecosystem, the mapping of ecosystem stakeholders was implemented
Life Cycle Assessment of an Industrial Laundry: a Case Study in the Italian Context
Full text linkThe high volumes of wastewater from industrial laundry with known toxicological concerns represent a relevant source of pollution for water bodies. Moreover, the unavailability of a detailed and specific Life Cycle Inventory (LCI) referring to the use of detergent within the laundry system could undermine the overall quality of the environmental assessment. This is related to the use of a substitutional product or proxy dataset for specific processes like the use of detergents. Laundry services are also known as highly energy consuming sites. This paper thus aims to make a Life Cycle Inventory (LCI) and Assessment (LCA) for an industrial laundry to provide the environmental profile for an Italian case study. The primary data input to finalize the LCI came from data collected directly from an Italian industrial laundry, integrated with literature, data provided from supporting databases (i.e. Ecoinvent 3.8), and data specifically obtained from the technical datasheets of detergents. The industrial laundry system considers the product’s overall supply chain: extraction and manufacturing of raw materials, including the detergent, transportation and logistics, the industrial process associated with the laundry activity, wastewater treatment, recirculation packaging, and final disposal stages. The calculated environmental profiles refer to the functional unit of 1 kg of linen washed by a standard washing cycle. The system boundaries of this study include the production stages of the process. The analysed activities are the transportation for the delivery and collection of linen, the purchase of raw materials, and the sanitization and washing processes. SimaPro 9.2 software and the ReCiPe 2016 H method are used for the LCA study. The baseline scenario has been compared with an alternative scenario introducing renewable energy technology (i.e. solar PV panel). The result shows a total impact of 12.77 mPt. The most impacting activities are the washing phase (4.62 mPt), the ironing phase (4.29 mPt), and the drying phase (1.56 mPt). The greatest impact in the washing phase is caused by the use of detergents and washing products. It is observed that most of the impacts fall into the categories of ‘Global Warming, Human Health’, ‘Fine Particulate Formation’, ‘Carcinogenic Human Toxicity’, ‘Non- Carcinogenic Human Toxicity’, ‘Fossil Resource Scarcity’. The midpoint category with the highest impact is ‘Fine Particulate Formation’ with a value of 5.18 mPt. The alternative scenario introducing renewable energy technology (i.e. solar PV panel) reduces the impact by 19.7 %. Sensitivity analyses have been performed to evaluate the LCA model’s uncertainty, with specific reference to the washing agents, the transportation of raw materials, and the energy consumption
Revolutionizing the Building Envelope: A Comprehensive Scientific Review of Innovative Technologies for Reduced Emissions
Full text linkThe energy and thermal performance of buildings is heavily dependent on the building envelope. As such, innovative environmental building envelope technologies are being developed to improve building energy efficiency and reduce greenhouse gas emissions. This paper provides a comprehensive review of the latest environmental building envelope technologies, such as phase-change materials (PCM), aerogel, and active and adaptive systems, to offer an overview of the current state-of-the-art in the field and identify future research directions. PCM technology has the potential to improve thermal comfort and reduce energy consumption by reducing peak heating and cooling loads. Paraffin wax is the most reliable PCM for use in building envelopes, and studies have shown that it can reduce heating and cooling energy consumption by up to 20 % compared to traditional insulation materials. Aerogel is a low-density and highly insulating material that has been shown to enhance thermal insulation and reduce heat transfer in buildings. Silica aerogel can provide thermal performance up to 2–4 times higher than traditional insulation materials, resulting in significant energy savings of up to 50 %. Active and adaptive systems, such as smart windows and dynamic insulation, allow for real-time control of building envelope performance, further improving energy efficiency and indoor comfort. Smart windows can lead to energy savings of up to 20–30 % compared to traditional windows, while dynamic insulation systems can provide energy savings of up to 50 % compared to traditional insulation materials. The review assesses various adaptive facade solutions based on their suitability for diverse climate zones, versatility in application, global availability of materials used, and energy efficiency. Despite the challenges and limitations of these technologies, including high costs, lack of widespread adoption, and limited understanding of long-term performance, the authors conclude that continued development and implementation of these technologies have the potential to make significant contributions to improving building energy efficiency and reducing greenhouse gas emissions. This review provides a valuable resource for researchers and practitioners working in the field of building envelopes and offers insights into the future research directions necessary to further advance the field
Effect of DGs on Power Quality of Distribution System: An Analytical Review
No full textThis article offers an overview of distributed generation (DG) in distribution systems (DS). The primary goal of this study is to assess the performance of DGs in DS. Due to the rise in electrical energy consumption, it is anticipated that DG sources would be essential to DS. Future power generating networks have a bright outlook on consideration of DG’s potential for utilising alternative energy sources. The quality of power systems is a crucial concern for energy providers and consumers. In order to decrease reliance on fossil fuels for the production of electricity, distributed generations are gaining importance in the energy supply networks in many countries. Distributed generators are small units that generate electricity close to customer sites. These DGs use renewable energy methods such as wind energy, solar energy and geothermal energy. The incorporation of DGs into a conventional power supply system evolves in a number of side effects, including an increase in the number of short circuits, higher power losses, a decrease in the quality of the energy produced, voltage transients, problems with voltage stability, coordination issues regarding voltage regulation and protection, the possibility that system protection will not function correctly, and the fact that there is less residual current input as a result of the DG bidirectional power flows. This review paper discusses the impacts of the penetration of DG into DS and provides various strategies to mitigate these effects
Variability Modeling in Enterprise Architecture Management: Case Study and Survey on Existing Approaches
No full textManaging and dealing with variability in business processes and the IT landscape is a common challenge in the everyday practice of most enterprises and organizations. Recent studies have observed that digital transformation, Internet-of-Things solutions and the introduction of artificial intelligence cause changes and challenges in enterprises that simultaneously require variability on several levels, for instance, business processes, data architecture, and services. Enterprise architecture models are considered a suitable way to visualize and manage dependencies between different levels of an enterprise. However, the management of variability in enterprise architectures has not received much attention in scientific research. This article aims to contribute to a better understanding of future investigation needs. Using a systematic literature analysis, the article structures the existing research work in the field and examines real-world challenges of variability based on a case study. We argue that there is a need for new constructs in enterprise architecture models that allow for expressing dependencies between variations on different enterprise architecture layers