@article{MehtaEhrenwirthMissalletal.2021, author = {Mehta, Kedar and Ehrenwirth, Mathias and Missall, Siegmund and Degembaeva, Nadira and Akmatov, Kuban and Z{\"o}rner, Wilfried}, title = {Energy Profiling of a High-Altitude Kyrgyz Community: Challenges and Motivations to Preserve Floodplain Ecosystems Based on Household Survey}, volume = {13}, pages = {13086}, journal = {Sustainability}, number = {23}, publisher = {MDPI}, address = {Basel}, issn = {2071-1050}, doi = {https://doi.org/10.3390/su132313086}, year = {2021}, abstract = {The floodplain areas along the Naryn River in Kyrgyzstan are essential as they hold the riparian (local) ecosystems because they provide firewood, pastureland, and areas for recreation and protection against erosion. Due to limited access to adequate, reliable, and sustainable energy services, the rural population usually derived their energy needs from multiple natural energy resources (i.e., firewood, charcoal, agricultural residues, animal dung, and wood branches). This is considered a common and predominant practice in rural Kyrgyzstan. This situation leads to a negative impact on local ecosystem services. In addition to that, the reliance on solid fuels contributes to indoor and outdoor air pollution, which is partially threatening the local ecosystem services. By contrast, the employment of renewable-based energy supply systems would substantially reduce the burden on the environment, which is mainly untapped. To integrate renewable energies, it is important to understand the energy behavior of floodplain communities. In that response, the presented article is the first attempt to capture the energy identity of the floodplain community of Kyrgyzstan based on a quantitative energy-based (on-site) household survey. Furthermore, the present research article synthesizes the driving factors that have a (direct or indirect) impact on the energy and local ecosystem services. In addition, the present article proposes a brief pathway for the sustainable energy transition. The article records the recommendation to integrate renewable energies to preserve the local ecosystems of Kyrgyzstan.}, language = {en} } @article{MehtaEhrenwirthTrinkletal.2021, author = {Mehta, Kedar and Ehrenwirth, Mathias and Trinkl, Christoph and Z{\"o}rner, Wilfried and Greenough, Richard}, title = {The energy situation in Central Asia}, volume = {14}, pages = {2805}, journal = {Energies}, subtitle = {a comprehensive energy review focusing on rural areas}, number = {10}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en14102805}, year = {2021}, abstract = {The northern part of the globe is dominated by industrialisation and is well-developed. For many years, the southern part of the world (South Asia, Africa etc.) has been a target of research concentrating on access to energy (mainly electricity) in rural regions. However, the Central Asian region has not been a focus of energy research compared to South East Asia and Africa. Despite plentiful domestically available energy resources, the energy supply in Central Asia is very unevenly distributed between urban and rural areas. Almost half of the total population of Central Asia lives in rural areas and there is a lack of access to modern energy services to meet primary needs. To analyse the energy situation (i.e., electricity, heating, hot water consumption, cooking, etc.) in rural Central Asia, this paper reviews residential energy consumption trends in rural Central Asian regions as compared to urban areas. Furthermore, the paper illustrates the potential of renewable energies in Central Asia. To perform the study, a qualitative comparative analysis was conducted based on a literature review, data, and statistical information. In summary, the presented article discusses the rural energy situation analytically and provides in-depth insights of Central Asian energy infrastructure.}, language = {en} } @article{VannahmeEhrenwirthSchrag2021, author = {Vannahme, Anna and Ehrenwirth, Mathias and Schrag, Tobias}, title = {Enhancement of a district heating substation as part of a low-investment optimization strategy for district heating systems}, volume = {10}, pages = {53}, journal = {Resources}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {2079-9276}, doi = {https://doi.org/10.3390/resources10050053}, year = {2021}, abstract = {In an ongoing project, low-investment measures for the optimization of district heating systems are analyzed. The optimization strategies are collected in a catalog, which is the core of a guideline. The application of this guideline is demonstrated using two concrete district heating networks as examples. In this study, the improvement of an analog controlled district heating substation by an electronic controller is investigated. High supply temperatures and heat losses are often a challenge in district heating networks. The district heating substations have a major influence on the network return temperatures. The comparison of the two substation setups with analog and electronic controllers is carried out by laboratory measurement. It can be shown that the return temperatures can be reduced by an average of 20 K in winter and transition, as well as 16 K in summer. The district heating network losses are calculated for one of both specific district heating networks. They are calculated from the ratio of network losses to generated energy. The generated energy is the sum of network losses and consumer demand. The thermal losses of the network can be reduced by 3\%. The volume flow in the heating network can be reduced to a quarter. Therefore, the pumping energy requirement drops sharply since these changes cubically affect the volume flow}, language = {en} } @article{BugajeEhrenwirthTrinkletal.2021, author = {Bugaje, Aminu and Ehrenwirth, Mathias and Trinkl, Christoph and Z{\"o}rner, Wilfried}, title = {Electric two-wheeler vehicle integration into rural off-grid photovoltaic system in Kenya}, volume = {14}, pages = {7956}, journal = {Energies}, number = {23}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en14237956}, year = {2021}, abstract = {In both rural and urban areas, two-wheeler vehicles are the most common means of transportation, contributing to local air pollution and greenhouse gas emissions (GHG). Transitioning to electric two-wheeler vehicles can help reduce GHG emissions while also increasing the socioeconomic status of people in rural Kenya. Renewable energy systems can play a significant role in charging electric two-wheeled vehicles, resulting in lower carbon emissions and increased renewable energy penetration in rural Kenya. As a result, using the Conventional and Renewable Energy Optimization (CARNOT) Toolbox in the MATLAB/Simulink environment, this paper focuses on integrating and modeling electric two-wheeled vehicles (e-bikes) into an off-grid photovoltaic Water-Energy Hub located in the Lake Victoria Region of Western Kenya. Electricity demand data obtained from the Water-Energy Hub was investigated and analyzed. Potential solar energy surplus was identified and the surplus was used to incorporate the electric two-wheeler vehicles. The energy consumption of the electric two-wheeler vehicles was also measured in the field based on the rider's driving behavior. The modeling results revealed an annual power consumption of 27,267 kWh, a photovoltaic (PV) electricity production of 37,785 kWh, and an electricity deficit of 370 kWh. The annual results show that PV generation exceeds power consumption, implying that there should be no electricity deficit. The results, however, do not represent the results in hourly resolution, ignoring the impact of weather fluctuation on PV production. As a result, in order to comprehend the electricity deficit, hourly resolution results are shown. A load optimization method was designed to efficiently integrate the electric 2-wheeler vehicle into the Water-Energy Hub in order to alleviate the electricity deficit. The yearly electricity deficit was decreased to 1 kWh and the annual electricity consumption was raised by 11\% (i.e., 30,767 kWh), which is enough to charge four more electric two-wheeler batteries daily using the load optimization technique.}, language = {en} } @inproceedings{BeringerMehtaEhrenwirthetal.2021, author = {Beringer, Jakob and Mehta, Kedar and Ehrenwirth, Mathias and Z{\"o}rner, Wilfried}, title = {Sustainable materials for insulating high-altitude rural Kyrgyz residential houses: A parametric economic study}, booktitle = {Applied Research Conference 2021, Conference Proceedings}, editor = {S{\"o}llner, Matthias and Pirkl, Gerald}, publisher = {Ostbayerische Technische Hochschule Amberg-Weiden}, address = {Amberg}, url = {https://www.oth-aw.de/files/oth-aw/Aktuelles/Veroeffentlichungen/Applied_Research_Conference_ARC2021_Proceedings.pdf}, pages = {183 -- 188}, year = {2021}, language = {en} } @inproceedings{KnepperEhrenwirthZoerner2021, author = {Knepper, Karoline and Ehrenwirth, Mathias and Z{\"o}rner, Wilfried}, title = {Potential of e- mobility in rural areas - Evaluation of opportunities and barriers based on literature review}, booktitle = {Applied Research Conference 2021, Conference Proceedings}, editor = {S{\"o}llner, Matthias and Pirkl, Gerald}, publisher = {Ostbayerische Technische Hochschule Amberg-Weiden}, address = {Amberg}, url = {https://www.oth-aw.de/files/oth-aw/Aktuelles/Veroeffentlichungen/Applied_Research_Conference_ARC2021_Proceedings.pdf}, pages = {216 -- 220}, year = {2021}, language = {en} } @inproceedings{BugajeYadavMehtaetal.2021, author = {Bugaje, Aminu and Yadav, Akhilesh and Mehta, Kedar and Ojinji, Felicia and Ehrenwirth, Mathias and Trinkl, Christoph and Z{\"o}rner, Wilfried}, title = {Influence of input parameters on artificial neural networks for off-grid solar photovoltaic power forecasting}, booktitle = {NEIS 2021}, editor = {Schulz, Detlef}, publisher = {VDE Verlag}, address = {Berlin}, isbn = {978-3-8007-5651-3}, url = {https://www.vde-verlag.de/proceedings-en/565651017.html}, pages = {135 -- 141}, year = {2021}, language = {en} } @inproceedings{BugajeEhrenwirthTrinkletal.2020, author = {Bugaje, Aminu and Ehrenwirth, Mathias and Trinkl, Christoph and B{\"a}r, Katharina and Z{\"o}rner, Wilfried}, title = {Development of a load management algorithm using nonlinear programming (NLP) for optimum integration of electric-mobility solutions into rural off-grid PV systems}, booktitle = {NEIS 2020}, editor = {Schulz, Detlef}, publisher = {VDE Verlag}, address = {Berlin}, isbn = {978-3-8007-5359-8}, url = {https://www.vde-verlag.de/proceedings-en/565359022.html}, pages = {167 -- 172}, year = {2020}, language = {en} } @inproceedings{MehtaEhrenwirthTrinkletal.2020, author = {Mehta, Kedar and Ehrenwirth, Mathias and Trinkl, Christoph and Z{\"o}rner, Wilfried and Greenough, Richard}, title = {A parametric study on the feasibility of solar-thermal space heating and hot water preparation under cold climates in Central Asian rural areas}, booktitle = {EuroSun 2020 Proceedings}, publisher = {International Solar Energy Society}, address = {Freiburg}, doi = {https://dx.doi.org/10.18086/eurosun.2020.04.03}, year = {2020}, language = {en} } @inproceedings{MehtaEhrenwirthTrinkletal.2020, author = {Mehta, Kedar and Ehrenwirth, Mathias and Trinkl, Christoph and Z{\"o}rner, Wilfried and Greenough, Richard}, title = {Impact of locally available thermal insulation structures on space heating demand of high-altitude rural buildings}, booktitle = {EuroSun 2020 Proceedings}, subtitle = {a case study of Kyrgyzstan}, publisher = {International Solar Energy Society}, address = {Freiburg}, doi = {https://dx.doi.org/10.18086/eurosun.2020.04.04}, year = {2020}, language = {en} } @article{WernerEhrenwirthMuschiketal.2021, author = {Werner, Melanie and Ehrenwirth, Mathias and Muschik, Sebastian and Trinkl, Christoph and Schrag, Tobias}, title = {Operational experiences with a temperature-variable district heating network for a rural community}, volume = {46}, journal = {Chemical Engineering \& Technology}, number = {3}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0930-7516}, doi = {https://doi.org/10.1002/ceat.202100114}, pages = {482 -- 490}, year = {2021}, abstract = {The potential of utilizing temperature-variable district heating systems in rural areas was investigated. A local district heating system in Germany and the related project NATAR are briefly described; measurement data is evaluated. Operational experiences with a seasonal temperature reduction and consequent advantages for different heat generation systems and heat storages are discussed. The analysis of measurement data reveals a high optimization potential for solar thermal systems in case of an integration both into a low- and a high-temperature storage. Furthermore, a combined heat-and-power plant in combination with a CO2 heat pump promises sector-coupling potential and high electricity self-consumption.}, language = {en} } @inproceedings{LauermannBetzMehtaetal.2020, author = {Lauermann, Magdalena and Betz, Florian and Mehta, Kedar and Thevs, Niels and Ehrenwirth, Mathias and Z{\"o}rner, Wilfried and Cyffka, Bernd}, title = {Preservation of Selected Ecosystem Services in the Floodplains of the Naryn River (Kyrgyzstan): Introducing the {\"O}koFlussPlan Project}, booktitle = {Beitr{\"a}ge zum 50. und 51. Jahrestreffen des Arbeitskreises Hydrologie 2018 in Koblenz und 2019 in Heidelberg}, publisher = {Institut f{\"u}r Geographie, Universit{\"a}t Augsburg}, address = {Augsburg}, url = {https://www.uni-augsburg.de/de/fakultaet/fai/geo/forschung/geographicaaugustana/}, pages = {47 -- 53}, year = {2020}, language = {en} } @inproceedings{RammEhrenwirthSchrag2019, author = {Ramm, Tobias and Ehrenwirth, Mathias and Schrag, Tobias}, title = {Modelling of the central heating station within a district heating system with variable temperatures}, booktitle = {Proceedings of the 13th International Modelica Conference}, editor = {Haumer, Anton}, publisher = {Modelica Association and Link{\"o}ping University Electronic Press}, address = {Link{\"o}ping}, isbn = {978-91-7685-122-7}, issn = {1650-3686}, doi = {http://dx.doi.org/10.3384/ecp19157567}, pages = {567 -- 576}, year = {2019}, language = {en} } @inproceedings{SchragEhrenwirthRammetal.2020, author = {Schrag, Tobias and Ehrenwirth, Mathias and Ramm, Tobias and Vannahme, Anna and Trinkl, Christoph}, title = {Solar energy use in district heating networks}, booktitle = {ICREEC 2019: Proceedings of the 1st International Conference on Renewable Energy and Energy Conversion}, editor = {Belasri, Ahmed and Beldjilali, Sid Ahmed}, publisher = {Springer}, address = {Singapur}, isbn = {978-981-15-5443-8}, issn = {2352-2534}, doi = {https://doi.org/10.1007/978-981-15-5444-5_1}, pages = {3 -- 10}, year = {2020}, language = {en} } @inproceedings{VannahmeRammEhrenwirthetal.2019, author = {Vannahme, Anna and Ramm, Tobias and Ehrenwirth, Mathias and Schrag, Tobias}, title = {Comparison of a usual heat-transfer-station with a hydraulic modified version under the aspect of exergy saving}, booktitle = {Proceedings of the 13th International Modelica Conference}, editor = {Haumer, Anton}, publisher = {Link{\"o}ping University Electronic Press}, address = {Link{\"o}ping}, isbn = {978-91-7685-122-7}, issn = {1650-3686}, doi = {http://dx.doi.org/10.3384/ecp19157647}, pages = {647 -- 654}, year = {2019}, language = {en} } @article{MehtaEhrenwirthTrinkletal.2022, author = {Mehta, Kedar and Ehrenwirth, Mathias and Trinkl, Christoph and Z{\"o}rner, Wilfried}, title = {Mapping Potential for Improving Rural Energy Services in Kyrgyzstan: Factors for Achieving Sustainable Development Goals in the Community Context}, volume = {3}, journal = {World}, number = {3}, publisher = {MDPI}, address = {Basel}, issn = {2673-4060}, doi = {https://doi.org/10.3390/world3030032}, pages = {586 -- 606}, year = {2022}, abstract = {Energy is a pivotal element for overall development. Therefore, affordable and clean energy for all (Sustainable Development Goal 7) is one of the important elements. Despite a suitable approach, Kyrgyzstan lags behind to achieve its Sustainable Development Goals by 2030. Improving access to energy can significantly impact the progress of many other sustainable development targets. However, access to reliable, sustainable, and adequate energy is a crucial task in rural Kyrgyzstan. Taking into consideration the energy situation and the importance of the availability of energy services, the overarching aim of the presented article is to map the potential of improving rural energy services to foster overall sustainable development goals. The article presents the most relevant information about rural energy usage behaviour based on three primary pillars: energy demand, energy carrier, and energy sources. In addition, the presented research article synthesises the key driving factors which have a direct or indirect impact on the energy services in rural areas. The summarised data displays a deep insight into a variety of complex and dynamic household energy consumption patterns. The article provides a potential solution nexus to foster improved energy services in rural Kyrgyzstan and therefore to foster the overall sustainable development in Kyrgyzstan. The findings of the article help to formulate a strategy to design rural energy services for policy makers and stockholders.}, language = {en} } @article{MehtaEhrenwirthTrinkletal.2022, author = {Mehta, Kedar and Ehrenwirth, Mathias and Trinkl, Christoph and Z{\"o}rner, Wilfried}, title = {Towards Sustainable Community Development through Renewable Energies in Kyrgyzstan: A Detailed Assessment and Outlook}, volume = {3}, journal = {World}, number = {2}, publisher = {MDPI}, address = {Basel}, issn = {2673-4060}, doi = {https://doi.org/10.3390/world3020018}, pages = {327 -- 343}, year = {2022}, abstract = {In rural Kyrgyzstan, the energy need is usually derived from multiple natural energy resources such as firewood, charcoal, agricultural residues, animal dung, and wood branches, which are considered common and predominant practices. Because of the non-sustainable resources and heavy reliance on the environment, Kyrgyzstan is one of the most vulnerable countries to climate change in Central Asia. On the contrary, the great renewable energy potential in Kyrgyzstan is untapped, which could be the most promising solution to ensuring sustainable energy supply in the country. However, because of the lack of scientific knowledge, current energy policies, and the lack of infrastructure, renewable resources are mainly untapped. To exploit the country's renewable energy potential, there is a need for a systematic diagnosis to develop a strategy to explore renewables in Kyrgyzstan, which is currently missing in the existing literature. In that regard, the presented study aims to assess the current status of renewable energy sources by considering the local energy context from a potential point of view. Further to this, it provides a comparative overview through a matrix of strengths, weaknesses, opportunities, and threats. Such novel analysis would be the fundamental base for formulating policy advice and a national plan to enhance the utilization of renewable energy in Kyrgyzstan. The presented analysis was carried out based on the extensive literature review, the country's national plan, and the existing energy policies of Kyrgyzstan. The article found out that there is huge potential available for the renewable energy market. As compared to other renewable energy sources, solar energy has great potential and can be considered one of the pioneer sustainable sources for integration into the country's power generation framework.}, language = {en} } @article{WernerMuschikEhrenwirthetal.2022, author = {Werner, Melanie and Muschik, Sebastian and Ehrenwirth, Mathias and Trinkl, Christoph and Schrag, Tobias}, title = {Sector Coupling Potential of a District Heating Network by Consideration of Residual Load and CO2 Emissions}, volume = {15}, pages = {6281}, journal = {Energies}, number = {17}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en15176281}, year = {2022}, abstract = {The growing share of fluctuating renewable electricity production within the German energy system causes the increasing necessity for flexible consumers, producers, and storage technologies to balance supply and demand. District heating networks with combined heat and power units, Power-to-Heat applications, and thermal energy storage capacities can serve as one of these flexible options. In this context, a simulation model of the district heating network of the rural community Dollnstein, Germany, was built. With the residual load of different regional areas (Germany, Bavaria, Eichst{\"a}tt, Dollnstein) it is investigated, how the heat generators can operate in an electricity market beneficial way. Two different control algorithms were evaluated: Due to a correlation between the residual loads and the CO2 emissions of the electricity mix, the CO2 savings achieved by this control algorithm are determined. Another way to operate electricity market beneficial is to consider the current CO2 emissions of each region. The main outcomes of this paper are, that there is a high potential for sector coupling by shifting the operation times of a CHP and a heat pump according to the residual load. The electricity demand of the heat pump can be met in terms of low CO2 emissions of the electricity mix, while the CHP can replace electricity with high CO2 emissions. These results can be improved, by considering not the residual load but the current CO2 emissions in the control algorithm.}, language = {en} } @article{BottEhrenwirthTrinkletal.2022, author = {Bott, Christoph and Ehrenwirth, Mathias and Trinkl, Christoph and Bayer, Peter}, title = {Component-based modeling of ground-coupled seasonal thermal energy storages}, volume = {2022}, pages = {118810}, journal = {Applied Thermal Engineering}, number = {214}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-5606}, doi = {https://doi.org/10.1016/j.applthermaleng.2022.118810}, year = {2022}, abstract = {Seasonal thermal energy storages are considered a central element of modern, innovative energy systems and help to harmonize fluctuating energy sources. Furthermore, they allow for an improved coupling between the electricity and heating sectors. Despite recent improvements of planning processes and enhanced models, significant discrepancies between projected and measured heat losses were revealed. Additional shortcomings of available tools relate to limitations in specifying geometry, internal design, or physical processes. Addressing these drawbacks, this study employs a revised, alternative approach by using a flexible, component-based, model ("STORE"). It allows variable flexible parameterizations to study diverse design scenarios. After introducing relevant seasonal thermal energy storage components, processes and mechanisms, datasets, and evaluation techniques, a plausibility test is presented that applies a common thermal energy storage model for benchmarking. In a test study, the re-use of a circa 1,000 m3 large swimming pool is simulated. STORE is used to investigate performance trends caused by different designs (e.g., insulation thicknesses, materials at individual interfaces). For the plausibility test, the results show a high degree of coverage and good applicability. Further, the results of the test study show a storage efficiency of 12.4\% for an uninsulated base case, which can be improved to 69.5\% in case of the most complex, highly insulated configuration. Critical trends are revealed, covering reduced peak capacity levels (26.5 to 23.5 MWh) and raised average filling temperatures (39.1 to 45.2 °C). Improved long-term behavior involves reduced environmental impacts due to reduced heating of the ambient soil (+7.9 K compared to +14.1 K after 2 years). General conclusions reveal that an optimal design should initially focus on an external cover of soil and top insulation. However, evaluations should base on multiple parameters depending on the target criteria. This is where the present model is highly useful. The capability of STORE to rapidly analyze a plethora of scenarios proves its high applicability for optimizing the planning processes of seasonal thermal energy storage projects.}, language = {en} } @article{VannahmeBuschEhrenwirthetal.2023, author = {Vannahme, Anna and Busch, Jonas and Ehrenwirth, Mathias and Schrag, Tobias}, title = {Experimental Study of District Heating Substations in a Hardware-in-the-Loop Test Rig}, volume = {12}, pages = {43}, journal = {Resources}, number = {4}, publisher = {MDPI}, address = {Basel}, issn = {2079-9276}, doi = {https://doi.org/10.3390/resources12040043}, year = {2023}, abstract = {This study compares two district heating substation systems for implementation in rural district heating networks with non-retrofitted single- and two-family houses. The aim is to determine which system has the potential to provide lower return temperatures and/or lower power peak demand. A hardware-in-the-loop-test rig was utilized to measure the two district heating substations under real operation conditions. This experimental study demonstrates that load balancing of the district heating network is attainable with the district heating substation with storage. This is especially advantageous when there is a high demand for domestic hot water. Overall, both systems yield comparable return temperatures.}, language = {en} }