The Scientific Journal of Riga Technical University
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Insights of Bioeconomy: Biopolymer Evaluation based on Sustainability Criteria
Full text linkSustainable development in the agriculture sector can be boosted by integrating a sustainable bioeconomy and transforming renewable resources into added-value products. There are various methods to determine, measure, and compare the extent of sustainability. We promote the bioeconomy concept by utilizing agricultural waste in biopolymers considering the sustainable development in the agriculture sector. This research aims to evaluate biopolymer alternatives based on sustainability criteria and indicators using the integrated multi-criteria decision analysis approach under the sustainability umbrella. The authors evaluated the PLA, PHA/PHB, starch, protein, and cellulose-based biopolymers. As a result, the cellulose-based biopolymer shows the best performance. The research findings provide valuable information to establish a sustainable pathway for biopolymer production for industries
Use of Single-cell Oils in the Production of Bio-based Epoxy: An Overview of the Most Suitable Microorganisms and Oil Properties
Full text linkEpoxy resins are widely used polymers that are mainly synthesized from fossil feedstocks. In order to reduce the use of fossil-derived epoxies, various solutions are widely studied, such as replacing conventional raw materials with more environmentally friendly, non-toxic solutions, such as vegetable oil. One of the less studied but potentially highly competitive feedstock for the synthesis of bio-based epoxies is single-cell oils (SCO). Single-cell oils have a number of advantages over vegetable oils, such as the fatty acid profiles of SCO are more suitable for the polymerization of epoxides, the production of SCOs is faster and more environmentally friendly. Thanks to the wide range of SCO-producing microorganisms, it is possible to find the exact SCO that is suitable for the specific application of the produced epoxy. Despite the potential advantages, SCO derived from microorganisms such as yeasts, fungi and bacteria, have received very limited coverage in the scientific literature. Therefore, this review summarizes the available information on single-cell oils and evaluates their suitability for use as feedstock in epoxide synthesis. The following aspects are reviewed in this paper: microorganism strains that can be used in the production of SCO; fermentation rates and SCO yields; applicable low-cost raw materials used for the cultivation of microorganisms; the fatty acid profile of the relevant SCO and other factors that are significant for suitability evaluation of the relevant SCO. To the best of authors knowledge this is the first review paper to summarize potential SCOs for their application in synthesis of bio-based epoxides and first paper to give an overview of fungal and bacterial oils for such application
Applicability of the Assessment Framework on Building Renovation of the European Union in Spain
Full text linkThe energy renovation of buildings is one of the main keys to achieve the decarbonisation objectives of the European Union as defined in the European Green Deal. To proceed with them, some of the main tools are the Energy Performance of Buildings Directive (EPBD) and the Commission Recommendation (EU) 2019/786, with an assessment framework composed by Measurable Progress Indicators (MPIs) to assess the decarbonisation process of the national building stock of the Member States. The objective of the study is to analyse the applicability of the MPIs of the assessment framework in Spain. The study carries out deep research of the viability of the MPIs in terms of data availability as well as a round table of 39 experts from different national organizations focused on the energy efficiency of buildings. Thus, the methodology is developed in three stages: (1) the analysis of the viability of each MPI in the Spanish context in terms of data availability; (2) prioritization of the MPIs through a round table of experts in energy efficiency of buildings; (3) critical evaluation of the priority MPIs regarding the efficient applicability in Spain. Firstly, the analysis of viability shows that it is possible to develop most of the MPIs of certain evaluation scopes, like ‘Overview of policies and actions to target the worst-performing segments of the national building stock’ with 6 out of 7 MPIs viable; however, in some other scopes very few or none of the MPIs are viable, like in ‘Policies and actions to target all public buildings’. Secondly, the expert round table prioritized 8 as the most important MPIs to evaluate the renovation of the national building stock, addressing different evaluation fields like environment and energy, renovation progress, social measures, and integration of technologies. Thirdly, the evaluation of the selected eight priority MPIs show that half of them is not viable in Spain according to the data availability, one partially viable, and only three of them are viable, but with limitations in the data quality; in the viable MPIs, the available data sources that allow the processability, exist only for two of them; georeferenced data exist for none of them. In conclusion, the MPIs of the EU’s assessment framework provide convenient indicators to assess the renovation of the national building stock according to the expert round table, but due to the data availability, it shows a limited applicability in the context of Spain
The Role Of Hydrogen In Future Climate-neutral Economy
Full text linkGlobal annual CO2 emissions have increased more than 16 times in 2021 compared to 1990 and are expected to keep growing. Renewable energy is a critical way to reduce the impact on the climate. However, renewable energy production’s power output does not necessarily match the demand. The intermittent character of renewable electricity generation requires the storage of produced energy. Green hydrogen production via electrolysis is an opportunity to increase the integration of renewable energy sources and move hard-to-decarbonize sectors to climate neutrality. This research aims to assess the potential role of hydrogen in decarbonizing the energy sector in Latvia in the long term. Latvia’s energy system is modeled using the input/output deterministic energy system analysis model EnergyPlan. The model includes all the primary energy demand sectors, energy production, and storage, and allows the analysis of the impact of different strategies on the total costs and emissions of the system by 2050. The results show that the production potential of green hydrogen will increase significantly by 2030, taking into account the existing plans for the installation of 800 MW of wind and solar generating capacity on a national scale. The most significant potential is associated with using hydrogen in the transport sector in vehicles and in producing alternative fuels. Other uses include the decarbonization of the natural gas sector. In these scenarios, it is possible to reduce CO2 emissions while annual system costs increase
Evaluating the Effectiveness of Agricultural and Forestry Policies in Achieving Environmental Goals through Environmental Policy Documents
Full text linkTo achieve the set climate targets by 2030 and become climate neutral by 2050, each Member State must develop a National Energy and Climate Plan (hereinafter – NECP) that contains practical and effective measures to achieve the targets set. The effectiveness of the agricultural and forestry measures defined in the Latvian NECP was assessed through the definition of appropriate indicators, an expert survey, and a composite sustainability index. The linkage between the measures or action lines in the Latvian NECP related to agriculture and forestry, the European Green Deal measures and the objectives of the European Union Bioeconomy Strategy was assessed. The results show that the effectiveness of agricultural and forestry measures is most influenced by factors such as quality, financing, and specificity. The description of the measures should be more detailed, with specific activities, indicators to be achieved, and amounts and funding sources planned for each activity. The lowest scoring measures are specific measures whose impacts cannot be measured and are not explicitly mentioned as relevant in the European Bioeconomy Strategy, the European Green Deal
Multidimensional Factors Influencing Renewable Energy Storage Deployment: PESLTE Analysis
Full text linkThe share of renewable energy in heat and power generation is expected to increase significantly and reach record levels in the coming decades. As a result, emerging energy storage technologies will be key elements in balancing the energy system. Compared to power generation technologies, storage technologies are considered one of the most complicated and least understood technologies for decarbonizing the energy system. There is still lack of understanding among scientists and policymakers about the choice of optimal integration of energy storage in carbon-neutral energy systems, as there are many multidimensional factors that influence this. In this study, the PESLTE analytical framework and composite index methodology is applied to examine the multidimensional factors that influence the deployment of renewable energy storage technologies: political (national and international level policy targets, appropriate regulation), economic (CAPEX, LCOE), social (public acceptance, knowledge and on-site capacity on RES storage in local energy supply enterprises), legal (level of bureaucracy and time of approval), technological (TRL, response time, efficiency level of complexity for technology to be integrated in the existing grid), and environmental (specific need for specific geographical condition, landscape friendliness, potential environmental risk, potential creation of environmental benefits, lifetime of technology, environmental impact)
On Carbon Storage and Substitution Factors of Harvested Wood Products in the Context of Climate Change Impacts of the Norwegian Forest Sector
Full text linkHarvested wood products (HWP) contribute to climate change mitigation via two main mechanisms: carbon storage and substitution. The authors examined the data on carbon storage and substitution factors of HWPs that are relevant in evaluating the climate change mitigation potential in the context of the Norwegian forest sector. While there seem to be many uncertainties in these parameters, the data suggest that several uses of wood for industrial products come with clear carbon substitution benefits and, in some cases, provide long-term carbon storage. Such wood products could play an important role in climate-friendly bioeconomic transformation. In particular, the authors considered wood- based construction materials, textile fibres, and insulation materials as examples of such products with potential in future bioeconomy. The decay of the carbon stored in HWP pools over time is often modelled using the product half-lives that correspond to the number of years it takes for the carbon in a pool to be reduced to half of its initial value. Using the default half-life values of greenhouse gases reported to the United Nations Framework Convention on Climate Change, the average half-life of carbon in HWPs produced by the forest industry in Norway of today is approximately 21 years. Shifting some of the use of pulpwood and sawn wood chips from producing paper and pellets to produce insulation materials or panels for construction would increase the time carbon is stored in the HWP pool. Accounting for the large uncertainty in the carbon substitution parameters of HWPs found in this study, a cautious estimate of the substitution benefits of HWPs produced in Norway can be considered to amount to at least 5 Mt CO2. Redirecting some pulpwood use from paper production to the production of textile fibres and the above-mentioned construction materials would increase the substitution benefits
Advancing Honey Bee Breeding: A Review of the Most Effective Methods for Introducing New Queen Bees
Full text linkThe aim of this review article is to identify the most commonly used methods for introducing new queen bees to a colony and to evaluate their success rates. Through a literature review, the authors select the most frequently used methods and assess their advantages and disadvantages, as well as the success rate for each method. While beekeepers have developed various methods for introducing new queen bees, there have been no comprehensive studies to determine which methods have the highest success rates. Successful introduction of a new queen bee is crucial for beekeeping, as unsuccessful introductions can result in the loss of queen bee material, colony collapse, development of laying worker bees and reduced productivity of the colony
Ranking of Electricity Accumulation Possibilities: Multicriteria Analysis
Full text linkThe pace of implementation of renewable electricity storage in Europe is disappointingly slow due to several factors. There is a need to speed up the rate and increase the volumes in order to promote a 100 % transition to renewable energy resources, expand the practice of using renewable energy, and contribute to the improvement of the user’s quality of life. In addition, a significant reduction of the global impact on the environment and climate change is an important factor. Electricity from renewable energy sources, such as the sun and wind, has a seasonal nature that cannot provide the necessary electricity for consumption and cannot cover peak loads. Also, the so-called 'energy resource crisis' is a topical issue, which reinforces the global need to increase the share of renewable energy resources in the overall balance of primary energy resources. It is precisely the wider integration of renewable electricity storage in practice that can help stimulate this. The availability of renewable electricity is constantly increasing, and the level of technological innovation is rapidly developing. Therefore, it is crucial to analyse both phenomena and actively search for overlaps in developing technologies, not forgetting the main differences in the types of accumulation, to promote accessibility, starting from a private house to the national and European scale. This article analyses and compares the options for renewable electricity storage – from small batteries to large storage systems. The authors consider the best solutions to satisfy individual and collective needs of the consumer. In this article, a multicriteria decision analysis (MCDA) and TOPSIS are used as analysis tools. After comparing nine criteria, such as the investment required, existing power density, efficiency, duration of operation, and others, in both groups, it is concluded that lithium-ion batteries are currently the best solution among batteries; while in the group of large accumulation systems pumped hydro storage secures a superior position
Beyond Well-Being: The Assessment of the Energy Renovation in Latvia by the Residents
Full text linkThe renovation of the multifamily buildings represents a key policy area and at the same time largely affects the daily life of residents. In the time of energy crisis, when energy price rises and saving energy becomes especially important, the building sector is among the most affected and a key sector to mitigate the consequences. The paper tackles the energy renovations of multi-family buildings in Latvia that use energy performance contracts. Specifically, it investigates how the process of renovation affects the resident’s health and well-being, their perception, and understanding of the renovation process. To evaluate the perception of the residents, a survey was conducted in thirteen buildings renovated by using energy performance contracting in three cities in Latvia. The survey addressed the preparation and execution of the energy renovation project, the state of the building before and after the renovation, and the impact of the renovated building on the residents. The survey revealed the lack of communication between the parties involved and co-design as the roadblocks to upscale the renovation process in Latvia. In particular, the financial communication to the residents on the project costs was insufficient. Additionally, even though the resident’s perception of safety, health, and comfort improved, the survey showed a decrease in communication between the residents of the same building after the renovation. Assessment of the survey results revealed the need to improve the communication by the ESCOs on the costs of the energy renovation projects and address the lack of community engagement after it is completed