TY - JOUR A1 - Vannahme, Anna A1 - Busch, Jonas A1 - Ehrenwirth, Mathias A1 - Schrag, Tobias T1 - Experimental Study of District Heating Substations in a Hardware-in-the-Loop Test Rig JF - Resources N2 - 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. UR - https://doi.org/10.3390/resources12040043 KW - district heating substation KW - local district heating network KW - non-retrofitted single- and two-family-houses KW - thermal hardware-in-the-loop test rig Y1 - 2023 UR - https://doi.org/10.3390/resources12040043 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-33382 SN - 2079-9276 VL - 12 IS - 4 PB - MDPI CY - Basel ER - TY - JOUR A1 - Igiligi, Anthony A1 - Vielhauer, Armin A1 - Ehrenwirth, Mathias A1 - Hurm, Christian A1 - Summ, Thorsten A1 - Trinkl, Christoph A1 - Navarro Gevers, Daniel T1 - Assessment of Conservation Voltage Reduction in Distribution Networks with Voltage Regulating Distribution Transformers JF - Energies N2 - The application of voltage reduction in medium and low voltage grids to reduce peak power demand or energy consumption has been implemented since the 1980s using several approaches. Conservation Voltage Reduction (CVR), as one such approach, uses a voltage control device to reduce or increase the voltage setpoint on a busbar, thereby reducing or increasing the amount of active and reactive power supply in the network. Voltage regulation for CVR is always implemented according to established network planning standards in each country. Research in this field has proven that a CVR factor (CVRf) of 0.7–1.5 for peak demand reduction can be achieved. This is an evaluation metric of CVR. The aim of this research is to determine and validate CVRf for peak demand reduction by comparing actual results obtained during regular tap changes with other randomly distributed periods outside tap change operations, using a set of measurement data. It is important to understand CVR deployment capability by evaluating CVR potentials from historical random tap operations before a robust network-wide deployment is introduced. This research provides such guidance. It also provides a novel approach to determining tap changes from voltage measurements using a time-based algorithm. A CVRf ranging from 0.95 to 1.61 was estimated using a measurement dataset from a test field. The result of the entire evaluation shows that the CVRf are smaller during peak PV production and greater during peak demand periods. Further evaluation using statistical hypotheses testing and a control chart was used to validate the evaluation. UR - https://doi.org/10.3390/en16073155 KW - conservation voltage reduction KW - peak power KW - tap change KW - voltage regulating distribution transformers Y1 - 2023 UR - https://doi.org/10.3390/en16073155 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-33449 SN - 1996-1073 VL - 16 IS - 7 PB - MDPI CY - Basel ER - TY - JOUR A1 - Hemmerle, Hannes A1 - Hale, Sina A1 - Dressel, Ingo A1 - Benz, Susanne A1 - Attard, Guillaume A1 - Blum, Philipp A1 - Bayer, Peter T1 - Estimation of Groundwater Temperatures in Paris, France JF - Geofluids N2 - Subsurface temperature data is usually only accessible as point information with a very limited number of observations. To spatialize these isolated insights underground, we usually rely on interpolation methods. Unfortunately, these conventional tools are in many cases not suitable to be applied to areas with high local variability, like densely populated areas, and in addition are very vulnerable to uneven distributions of wells. Since thermal conditions of the surface and shallow subsurface are coupled, we can utilize this relationship to estimate shallow groundwater temperatures from satellite-derived land surface temperatures. Here, we propose an estimation approach that provides spatial groundwater temperature data and can be applied to natural, urban, and mixed environments. To achieve this, we combine land surface temperatures with anthropogenic and natural processes, such as downward heat transfer from buildings, insulation through snow coverage, and latent heat flux in the form of evapotranspiration. This is demonstrated for the city of Paris, where measurements from as early as 1977 reveal the existence of a substantial subsurface urban heat island (SUHI) with a maximum groundwater temperature anomaly of around 7 K. It is demonstrated that groundwater temperatures in Paris can be well predicted with a root mean squared error of below 1 K by means of satellite-derived land surface images. This combined approach is shown to improve existing estimation procedures that are focused either on rural or on urban conditions. While they do not detect local hotspots caused by small-scaled heat sources located underground (e.g., sewage systems and tunnels), the findings for the city of Paris for the estimation of large-scale thermal anomalies in the subsurface are promising. Thus, the new estimation procedure may also be suitable for other cities to obtain a more reliable insight into the spatial distribution of urban ground and groundwater temperatures. UR - https://doi.org/10.1155/2019/5246307 Y1 - 2019 UR - https://doi.org/10.1155/2019/5246307 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-35817 SN - 1468-8123 VL - 2019 PB - Hindawi CY - London ER - TY - JOUR A1 - Tissen, Carolin A1 - Menberg, Kathrin A1 - Bayer, Peter A1 - Blum, Philipp T1 - Meeting the demand BT - geothermal heat supply rates for an urban quarter in Germany JF - Geothermal Energy - Science, Society and Technology N2 - Thermal energy for space heating and for domestic hot water use represents about a third of the overall energy demand in Germany. An alternative to non-renewable energy-based heat supply is the implementation of closed and open shallow geothermal systems, such as horizontal ground source heat pump systems, vertical ground source heat pump (vGSHP) systems and groundwater heat pump systems. Based on existing regulations and local hydrogeological conditions, the optimal site-specific system for heat supply has to be identified. In the presented technical feasibility study, various analytical solutions are tested for an urban quarter before and after building refurbishment. Geothermal heat supply rates are evaluated by providing information on the optimal system and the specific shortcomings. Our results show that standard vGSHP systems are even applicable in older and non-refurbished residential areas with a high heat demand using a borehole heat exchanger with a length of 100 m or in conjunction with multiple boreholes. After refurbishment, all studied shallow geothermal systems are able to cover the lowered heat demand. The presented analysis also demonstrates that ideally, various technological variants of geothermal systems should be evaluated for finding the optimal solution for existing, refurbished and newly developed residential areas. UR - https://doi.org/10.1186/s40517-019-0125-8 KW - Ground source heat pump (GSHP) KW - Groundwater heat pump (GWHP) KW - Borehole heat exchanger (BHE) KW - Heat demand KW - Refurbishment KW - Geothermal potential KW - GIS Y1 - 2019 UR - https://doi.org/10.1186/s40517-019-0125-8 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-35833 SN - 2195-9706 VL - 7 PB - BioMed Central CY - London ER - TY - JOUR A1 - Ringel, Lisa Maria A1 - Somogyvári, Márk A1 - Jalali, Mohammadreza A1 - Bayer, Peter T1 - Comparison of Hydraulic and Tracer Tomography for Discrete Fracture Network Inversion JF - Geosciences N2 - Fractures serve as highly conductive preferential flow paths for fluids in rocks, which are difficult to exactly reconstruct in numerical models. Especially, in low-conductive rocks, fractures are often the only pathways for advection of solutes and heat. The presented study compares the results from hydraulic and tracer tomography applied to invert a theoretical discrete fracture network (DFN) that is based on data from synthetic cross-well testing. For hydraulic tomography, pressure pulses in various injection intervals are induced and the pressure responses in the monitoring intervals of a nearby observation well are recorded. For tracer tomography, a conservative tracer is injected in different well levels and the depth-dependent breakthrough of the tracer is monitored. A recently introduced transdimensional Bayesian inversion procedure is applied for both tomographical methods, which adjusts the fracture positions, orientations, and numbers based on given geometrical fracture statistics. The used Metropolis-Hastings-Green algorithm is refined by the simultaneous estimation of the measurement error’s variance, that is, the measurement noise. Based on the presented application to invert the two-dimensional cross-section between source and the receiver well, the hydraulic tomography reveals itself to be more suitable for reconstructing the original DFN. This is based on a probabilistic representation of the inverted results by means of fracture probabilities. UR - https://doi.org/10.3390/geosciences9060274 KW - hydraulic tomography KW - tracer tomography KW - DFN KW - Bayesian inversion KW - heterogeneity KW - fracture KW - hydrogeophysics Y1 - 2019 UR - https://doi.org/10.3390/geosciences9060274 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-35858 SN - 2076-3263 VL - 9 IS - 6 PB - MDPI CY - Basel ER - TY - JOUR A1 - Schweizer, Manuel A1 - Tutunaru, Robin A1 - Holzhammer, Uwe T1 - Energie- und Leistungsbedarf des elektrischen Individualverkehrs JF - BWK ENERGIE. UR - doi.org/10.37544/1618-193X-2022-7-8 KW - Energiesystemmodellierung KW - Elektromobilität KW - Energiebedarf KW - Leistungsbedarf Y1 - 2022 UR - doi.org/10.37544/1618-193X-2022-7-8 SN - 1618-193X VL - 74 IS - 7-8 SP - 44 EP - 48 PB - VDI fachmedien CY - Düsseldorf ER - TY - JOUR A1 - Schweizer, Manuel A1 - Stöckl, Martin A1 - Tutunaru, Robin A1 - Holzhammer, Uwe T1 - Influence of heating, air conditioning and vehicle automation on the energy and power demand of electromobility JF - Energy Conversion and Management: X N2 - With the increasing number of electric vehicles in the transport sector, the relevance of accurate energy and power demand predictions of electromobility is growing. Thereby, different vehicle functions, especially heating and air conditioning and vehicle automation, have a significant influence. In accordance with the upcoming Euro-7 emissions standard, the energy consumption for heating even has to be contained in the manufacturer’s consumption data in the future. To increase the accuracy of energy and power demand predictions of electromobility, the energy consumption of vehicle functions such as heating and air conditioning as well as the energy savings through vehicle automation must be considered. This paper presents approaches for modeling and simulation the energy consumption of heating, air conditioning and vehicle automation which can be used as an extension of electric vehicles WLTP (Worldwide Harmonized Light-Duty Vehicles Test Procedure) consumption simulation on the level of vehicle classes. The Germany-wide results of the electric vehicles energy demand for heating and air conditioning on the level of NUTS3-areas (Nomenclature of territorial units for statistics) and vehicle classes show regionally different results and confirm the relevance of the research approach. Vehicle automation results are described on the level of the five SAE automation levels (Society of Automotive Engineers automation levels) and the vehicle classes. The approaches and results can be used for single vehicles or assumed vehicle fleets. UR - https://doi.org/10.1016/j.ecmx.2023.100443 KW - Energy system modelling KW - Electromobility KW - Heating and air conditioning KW - Vehicle automation KW - Energy demand KW - Power demand Y1 - 2023 UR - https://doi.org/10.1016/j.ecmx.2023.100443 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-38868 SN - 2590-1745 VL - 2023 IS - 20 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Summ, Thorsten A1 - Ehrenwirth, Mathias A1 - Trinkl, Christoph A1 - Zörner, Wilfried A1 - Pischow, Kaj A1 - Greenough, Richard A1 - Oyinlola, Muyiwa T1 - Effect of argon concentration on thermal efficiency of gas-filled insulating glass flat-plate collectors JF - Applied Thermal Engineering N2 - Insulating glass flat-plate collectors can save cost by being produced quickly and automatically in insulated glass production facilities, and they can be filled with argon to reduce heat loss. During its lifetime, the collector is likely to lose argon because of gradual material degradation of the sealing. However, information on the influence of the argon concentration on the collector efficiency is limited. Therefore, the objective of this research work was to analyse this effect. A theoretical material property calculation of argon-air mixtures was carried out to determine the convective losses with variable argon concentrations. Thermal collector performance was measured experimentally using an outdoor solar tracker test rig. The results strongly suggest, that the influence of argon concentration on both the convective losses and the thermal efficiency is non-linear. The measurements revealed that an argon concentration of 90 % can increase average thermal performance by 6.7 ± 4.8 percentage points. An increase in argon concentration from 0 % to 50 % has almost twice the effect on average thermal efficiency as an increase from 50 % to 90 %. Concluding from these results, an argon leakage threshold of 2.5 percentage points per year is proposed to avoid disproportionate loss of efficiency over time. UR - https://doi.org/10.1016/j.applthermaleng.2023.120657 KW - Insulating glass KW - Flat-plate collector KW - Argon KW - Gas concentration KW - Efficiency measurement KW - Convective heat transfer Y1 - 2023 UR - https://doi.org/10.1016/j.applthermaleng.2023.120657 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-37875 SN - 1873-5606 SN - 1359-4311 VL - 2023 IS - 230, Part A PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Besner, Rebekka A1 - Mehta, Kedar A1 - Zörner, Wilfried T1 - How to Enhance Energy Services in Informal Settlements? BT - Qualitative Comparison of Renewable Energy Solutions JF - Energies N2 - More than half of the urban population of Sub-Saharan Africa lives in informal housing conditions. While urban areas are, in general, characterized by a high electrification rate, residents of informal settlements are still affected by energy poverty, the use of traditional energy sources and unreliable electricity supply. The aim of the study is to give an overview of different renewable-energybased solutions which are able to improve local energy provision. These are Solar Home Systems, Mini-Grids, and Energy-Hubs. The technologies are compared to another option for improving energy supply, namely Grid Expansion. The analysis is based on 24 Key Performance Indicators, which can be classified into technical, economic, environmental, social, and political dimensions. The selection of indicators is based on the challenges prevalent in informal settlements that impede a comprehensive, sustainable energy supply. The literature-based indices are used to determine which of the four technologies is a suitable solution for minimizing the challenges prevailing in informal settlements. The resulting matrix provides a holistic comparison and serves as a decision aid in selecting the appropriate technology for future projects in informal settlements, depending on local conditions and the needs of the population. The results show that the Energy-Hub is a valid alternative for energy supply improvement in Informal Settlements. UR - https://doi.org/10.3390/en16124687 KW - informal settlements KW - energy access KW - Sub-Saharan Africa KW - Energy-Hub KW - Mini-Grid Y1 - 2023 UR - https://doi.org/10.3390/en16124687 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-37319 SN - 1996-1073 VL - 16 IS - 12 PB - MDPI CY - Basel ER - TY - JOUR A1 - Pophillat, William A1 - Attard, Guillaume A1 - Bayer, Peter A1 - Hecht-Méndez, Jozsef A1 - Blum, Philipp T1 - Analytical solutions for predicting thermal plumes of groundwater heat pump systems JF - Renewable Energy UR - https://doi.org/10.1016/j.renene.2018.07.148 Y1 - 2018 UR - https://doi.org/10.1016/j.renene.2018.07.148 SN - 1879-0682 VL - 2020 IS - 147, Part 2 SP - 2696 EP - 2707 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Attard, Guillaume A1 - Bayer, Peter A1 - Rossier, Yvan A1 - Blum, Philipp A1 - Eisenlohr, Laurent T1 - A novel concept for managing thermal interference between geothermal systems in cities JF - Renewable Energy UR - https://doi.org/10.1016/j.renene.2019.06.095 Y1 - 2019 UR - https://doi.org/10.1016/j.renene.2019.06.095 SN - 1879-0682 VL - 2020 IS - 145 SP - 914 EP - 924 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Pophillat, William A1 - Bayer, Peter A1 - Teyssier, Esther A1 - Blum, Philipp A1 - Attard, Guillaume T1 - Impact of groundwater heat pump systems on subsurface temperature under variable advection, conduction and dispersion JF - Geothermics UR - https://doi.org/10.1016/j.geothermics.2019.101721 Y1 - 2019 UR - https://doi.org/10.1016/j.geothermics.2019.101721 SN - 1879-3576 VL - 2020 IS - 83 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Selleneit, Volker A1 - Mast, Tanja A1 - Holzhammer, Uwe T1 - Method to describe and rate the ability to provide flexibility of residual power providers in electricity grids with a high share of variable renewable energies JF - CIRED - Open Access Proceedings Journal N2 - With an increasing ratio of variable renewable energies in Germany, power supply has to be ensured by providing flexibility from controllable supply and demand energy conversion units. For residual electricity supply, utilities in the industrial sector or flexible biogas plants may be suitable flexibility options. To describe and rate different technologies or utilities in terms of their ability to provide flexibility, a definition of flexibility and an innovative method to describe flexibility considering the grid requirements is elaborated. The method is based on a solid definition of flexibility indicators suitable for all technologies. For an increased flexibility, in many cases, it is reasonable to add supporting technologies like a storage to a utility or biogas combined heat and power (CHP). Such utility configurations can also be described with the elaborated method. The method can also make a valuable contribution to all distribution systems or utility system modellers as it can be taken as a basis for the modelling. In this study, the definition of flexibility indicators is described in detail and used on the example of a biogas CHP plant. UR - https://doi.org/10.1049/oap-cired.2021.0294 KW - Energy resources KW - Distribution networks KW - Thermal power stations and plants KW - Biofuel and biomass resources KW - Power supply quality and harmonics KW - Control of electric power systems Y1 - 2020 UR - https://doi.org/10.1049/oap-cired.2021.0294 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-17043 SN - 2515-0855 VL - 2020 IS - 1 SP - 154 EP - 157 PB - IET CY - Stevenage ER - TY - BOOK A1 - Eltrop, Ludger A1 - Nagel, Sylvio A1 - Holzhammer, Uwe A1 - Mast, Tanja A1 - Selleneit, Volker A1 - Tronnier, Annika A1 - Wachinger, Gisela ED - Eltrop, Ludger ED - Holzhammer, Uwe T1 - Methodenhandbuch "Bioenergie als Flexibilitätsoption im Energiesystem" T3 - Schriftenreihe "Energetische Biomassenutzung", Band 21 UR - https://doi.org/10.48480/m6ak-zr53 Y1 - 2021 UR - https://doi.org/10.48480/m6ak-zr53 SN - 2701-2719 PB - Deutsches Biomasseforschungszentrum gemeinnützige GmbH CY - Leipzig ER - TY - CHAP A1 - Dotzauer, Martin A1 - Büchner, Daniel A1 - Eltrop, Ludger A1 - Härdtlein, Marlies A1 - Henning, Christiane A1 - Herrmann, André A1 - Holzhammer, Uwe A1 - Kornatz, Peter A1 - Mast, Tanja A1 - Nagel, Sylvio A1 - Oehmichen, Katja A1 - Philipp, Matthias A1 - Pohl, Marcel A1 - Selleneit, Volker A1 - Thrän, Daniela ED - Thrän, Daniela ED - Pfeiffer, Diana T1 - Flexible Bereitstellung von Bioenergie T2 - Methodenhandbuch: Stoffstromorientierte Bilanzierung der Klimagaseffekte: Methoden zur Bestimmung von Technologiekennwerten, Gestehungskosten und Klimagaseffekten von Vorhaben im Rahmen des BMWi-Forschungsnetzwerkes Bioenergie/ BMWi-Förderbereich „Energetische Biomassenutzung“ UR - https://doi.org/10.48480/ddpt-ys74 Y1 - 2021 UR - https://doi.org/10.48480/ddpt-ys74 SN - 978-3-946629-58-0 SN - 2701-2719 SP - 56 EP - 108 PB - Deutsches Biomasseforschungszentrum gemeinnützige GmbH CY - Leipzig ET - Version 5 ER - TY - CHAP A1 - Mast, Tanja A1 - Holzhammer, Uwe A1 - Philipp, Matthias ED - Nelles, Michael T1 - SmartBio : Biogasanlagen als Akteur in neuen intelligenten, regionalen Märkten T2 - Tagungsband 12. Rostocker Bioenergieforum 2018 Y1 - 2018 UR - https://www.openagrar.de/receive/dimport_mods_00001878 SN - 978-3-86009-473-0 SP - 143 EP - 150 PB - Universität Rostock CY - Rostock ER - TY - CHAP A1 - Mast, Tanja A1 - Nagel, Sylvio A1 - Holzhammer, Uwe A1 - Eltrop, Ludger T1 - Biogasanlagen neu denken BT - technisch-ökonomische Charakterisierung für die Einbindung in die modellgestützte Systemanalyse T2 - Tagungsband 14. Rostocker Bioenergieforum 2020, 19. Dialog Abfallwirtschaft MV UR - https://doi.org/10.18453/rosdok_id00002650 Y1 - 2020 UR - https://doi.org/10.18453/rosdok_id00002650 SN - 978-3-86009-507-2 SP - 123 EP - 132 PB - Universität Rostock CY - Rostock ER - TY - CHAP A1 - Nagel, Sylvio A1 - Mast, Tanja A1 - Holzhammer, Uwe A1 - Eltrop, Ludger T1 - Die Rolle der Bioenergie im Energie- und Mobilitätssystem in Deutschland BT - Ergebnisse einer modellgestützten Systemanalyse T2 - Tagungsband 14. Rostocker Bioenergieforum 2020, 19. Dialog Abfallwirtschaft MV UR - https://doi.org/10.18453/rosdok_id00002650 Y1 - 2020 UR - https://doi.org/10.18453/rosdok_id00002650 SN - 978-3-86009- 507-2 SP - 47 EP - 56 PB - Universität Rostock CY - Rostock ER - TY - CHAP A1 - Mast, Tanja A1 - Koller, Maria A1 - Holzhammer, Uwe T1 - Verfügbarkeit und Erlösmöglichkeiten unterschiedlicher Biogasanlagenkonzepte im Smart-Market-Ansatz T2 - Tagungsband 14. Rostocker Bioenergieforum 2020, 19. Dialog Abfallwirtschaft MV UR - https://doi.org/10.18453/rosdok_id00002650 Y1 - 2020 UR - https://doi.org/10.18453/rosdok_id00002650 SN - 978-3-86009- 507-2 SP - 391 EP - 397 PB - Universität Rostock CY - Rostock ER - TY - JOUR A1 - El Makroum, Reda A1 - Khallaayoun, Ahmed A1 - Lghoul, Rachid A1 - Mehta, Kedar A1 - Zörner, Wilfried T1 - Home Energy Management System Based on Genetic Algorithm for Load Scheduling: A Case Study Based on Real Life Consumption Data JF - Energies N2 - This paper proposes a home energy management system able to achieve optimized load scheduling for the operation of appliances within a given household. The system, based on the genetic algorithm, provides recommendations for the user to improve the way the energy needs of the home are handled. These recommendations not only take into account the dynamic pricing of electricity, but also the optimization for solar energy usage as well as user comfort. Historical data regarding the times at which the appliances have been used is leveraged through a statistical method to integrate the user’s preference into the algorithm. Based on real life appliance consumption data collected from a household in Morocco, three scenarios are established to assess the performance of the proposed system with each scenario having different parameters. Running the scenarios on the developed MATLAB script shows a cost saving of up to 63.48% as compared to a base scenario for a specific day. These results demonstrate that significant cost saving can be achieved while maintaining user comfort. The addition of supplementary shiftable loads (i.e., an electric vehicle) to the household as well as the limitations of such home energy management systems are discussed. The main contribution of this paper is the real data and including the user comfort as a metric in in the home energy management scheme. UR - https://doi.org/10.3390/en16062698 KW - home energy management KW - load scheduling KW - genetic algorithm KW - user comfort Y1 - 2023 UR - https://doi.org/10.3390/en16062698 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-32284 SN - 1996-1073 VL - 16 IS - 6 PB - MDPI CY - Basel ER - TY - JOUR A1 - Kaminski Küster, Kristie A1 - Daniel, Gebbran A1 - Aoki, Alexandre Rasi A1 - Lambert-Torres, Germano A1 - Navarro Gevers, Daniel A1 - Impinnisi, Patricio A1 - da Silva Pinto, Cleverson Luiz T1 - Adoption of Local Peer-to-Peer Energy Markets: Technical and Economical Perspectives for Utilities JF - Energies N2 - Peer-to-peer (P2P) energy markets constitute a promising approach for locally coordinating the increasing amount of distributed energy resources (DERs) in the distribution system. Although the benefits of P2P markets for the prosumers are already well understood, their impact on utilities is not well discussed nor well understood. This hinders the development of regulatory frameworks, which are still needed to allow for the widespread adoption of decentralized energy markets in any interested country. So far, research has been conducted in specific isolated aspects, making it difficult to understand the overall implications for utilities. The present study aims to tackle this research gap by comprehensively evaluating P2P markets’ effects, considering utilities as primary stakeholders. A qualitative roadmap with the overall benefits and challenges of adopting P2P by utilities is outlined to reach this purpose. Technical and economic criteria are assigned for comparing a P2P market to the current regulatory framework. Each criterion is evaluated in a co-simulation platform connecting a market model to a power flow model. Market performance is assessed by revenue analysis, and grid operation indicators evaluate grid performance. Furthermore, network fees are introduced as compensation mechanisms for the net revenue loss. Comparison scenarios encompass network fees and the number of agents, PV, and storage penetration. Results demonstrate that there is no possible benefit for both utilities and prosumers simultaneously if looking exclusively at the financial balance of the market. An equilibrium in benefits for all stakeholders is achievable if non-financial metrics are considered in an integrated market and fee structure analysis. Moreover, results demonstrate that the design of market structures must be sensitive to network configurations and DER penetration changes. This study contributes toward comprehending how the utilities could embrace P2P markets as a feasible solution for grid coordination challenges, opening a new set of questions for further research. UR - https://doi.org/10.3390/en16052364 KW - co-simulation KW - distributed energy resources KW - impact analysis KW - local energy markets KW - microgrids KW - peer-to-peer energy trading Y1 - 2023 UR - https://doi.org/10.3390/en16052364 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-32304 SN - 1996-1073 VL - 16 IS - 5 PB - MDPI CY - Basel ER - TY - JOUR A1 - Stöckl, Martin A1 - Idda, Johannes A1 - Selleneit, Volker A1 - Holzhammer, Uwe T1 - Flexible Operation to Reduce Greenhouse Gas Emissions along the Cold Chain for Chilling, Storage, and Transportation - A Case Study for Dairy Products JF - Sustainability N2 - The further expansion of renewable energies in Germany requires flexible consumers to balance fluctuations in electricity production from variable renewable energies. Cold storage warehouses, due to their inherent storage capacity and widespread use, are well-suited for integrating more renewable energies. The potential of cold storage warehouses is often viewed in isolation and not in conjunction with the cold chain’s upstream and downstream processes. By adjusting the temperatures within the processes, the individual links in the cold chain can be made flexible. To assess the effects of flexibilization on emissions and electricity costs, thermodynamic models of the individual links in the cold chain and of a yogurt pallet are developed and linked together. Due to temperature fluctuations in the products resulting from the flexibilization, emission evaluations must be considered throughout the cold chain. Results of the simulation for the study period show that emissions reductions and electricity cost savings can be achieved in all three links when they are made flexible. However, the savings vary in magnitude. Only minor savings can be achieved in the cooling tunnel. The greatest potential for savings is in refrigerated transport, if deeper cooling occurs in the process before, i.e., in the cold storage warehouse. UR - https://doi.org/10.3390/su152115555 KW - flexibility KW - flexible energy demand KW - system efficiency KW - cold storage warehouse KW - refrigerated transport KW - cold chain KW - variable renewable energies KW - industry KW - dairies Y1 - 2023 UR - https://doi.org/10.3390/su152115555 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-40844 SN - 2071-1050 VL - 15 IS - 21 PB - MDPI CY - Basel ER - TY - CHAP A1 - Schmitt, David A1 - Reum, Tobias A1 - Summ, Thorsten A1 - Trinkl, Christoph A1 - Schrag, Tobias ED - Droege, Peter ED - Quint, Lelia T1 - Potential of a Long-Term Predictive Controller for Managing Energy Storages to Reduce the Electric Grid-Load of an Air-Source Heat Pump T2 - Proceedings of the International Renewable Energy Storage and Systems Conference (IRES 2023) N2 - Electrifying the domestic heating sector is mandatory to decarbonize the buildings sector but leads to additional peak loads in the public grid. Air-source heat pumps the mostly used technology in this regard even though, they suffer from lower efficiency during times of high heat demands. The usage of energy storages and predictive controllers enables operation shifting and hence offers potential to decrease the peak loads in the electric grid. This potential can be increased by using a longer prediction horizon as extended operation shifting can be performed. In this contribution, a methodology to derive the theoretical potential on the grid peak load reduction of such a long-term predictive controller is introduced. The electric load profile of an air-source heat pump in a typical German single-family home was generated based on different weather data scenarios for the city of Ingolstadt. Based on the profile the dependency between peak load reduction and required storage capacity was identified. In the case study a reduction of the peak load from 21 – 31% for an unrenovated building was achieved using a 500 L buffer storage. Further investigation needs to be done to derive a more realistic potential for renovated or new buildings. UR - https://doi.org/10.2991/978-94-6463-455-6_21 Y1 - 2024 UR - https://doi.org/10.2991/978-94-6463-455-6_21 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-49963 SN - 978-94-6463-455-6 SP - 205 EP - 211 PB - Atlantis Press CY - Dordrecht ER - TY - JOUR A1 - Selleneit, Volker A1 - Holzhammer, Uwe T1 - Eigenenergieversorgung oder mehr Resilienz durch Flexibilisierung? JF - VDI energie + umwelt UR - https://doi.org/10.37544/2942-7347-2024-5-6-53 Y1 - 2024 UR - https://doi.org/10.37544/2942-7347-2024-5-6-53 SN - 2942-7347 VL - 1 IS - 5-6 SP - 53 EP - 57 PB - VDI Fachmedien CY - Düsseldorf ER - TY - JOUR A1 - Mehta, Kedar A1 - Shah, Meeth Jeetendra A1 - Zörner, Wilfried T1 - Agri-PV (Agrivoltaics) in Developing Countries: Advancing Sustainable Farming to Address the Water–Energy–Food Nexus JF - Energies N2 - The escalating demand for water, energy, and food, coupled with the imperative for sustainable development, necessitates innovative solutions to address the complex interdependencies within the water–energy–food nexus. In this context, agriculture and photovoltaics (Agri-PV or Agri–voltaics) systems have emerged as a promising approach to promoting sustainable agricultural practices while enhancing energy efficiency and food production. However, limited research, especially on the technical aspects of Agri-PV, has resulted in a knowledge gap regarding how to model and determine the suitability of Agri-PV for different crops based on local conditions. This study presents a novel approach to modeling and simulating Agri-PV systems for various major crops in developing countries, using Uzbekistan as a case study. It provides a blueprint for selecting suitable Agri-PV systems. The research investigates the technical feasibility of Agri-PV technology tailored to Uzbekistan’s agricultural landscape, with broader implications for Central Asia. Employing a systematic methodology, the study begins by selecting appropriate sites and crops for Agri-PV system testing, ensuring the relevance and applicability of the research findings to the local context. Using advanced software tools such as PVSyst, the study accurately calculates photosynthetically active radiation (PAR) values specific to selected crops, bridging a significant knowledge gap and providing empirical data essential for informed decision making. The methodology further incorporates an in-depth analysis of economic and technical considerations in selecting PV modules and inverters, enhancing the scientific accuracy of the study. By strategically modeling Agri-PV systems based on parameters like row density, module distance, and tilt angle, this research aims to optimize the integration of photovoltaic technology with agricultural practices in Uzbekistan. Moreover, this study helps to understand the impact of Agri-PV systems on the water–energy–food nexus, providing valuable insights into the potential benefits and challenges specific to the region. The study identifies the positive impact of Agri-PV on major crops and provides a suitable design and modeling approach for sustainable farming practices. UR - https://doi.org/10.3390/en17174440 Y1 - 2024 UR - https://doi.org/10.3390/en17174440 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-51677 SN - 1996-1073 VL - 17 IS - 17 PB - MDPI CY - Basel ER - TY - JOUR A1 - Vannahme, Anna A1 - Ehrenwirth, Mathias A1 - Schrag, Tobias T1 - Development and application of a guideline for assessing optimization potentials for district heating systems JF - Energy N2 - Integrating renewable energies into district heating systems has a large potential to reduce CO2-emissions in the heating sector. As district heating systems offer the possibility of incorporating renewable energies into the heat supply, new systems have to be built and the existing networks must be maintained. This study investigates ways to optimize existing district heating systems in order to ensure economic sustainability in the long-term. Previous case studies have elaborated on a variety of optimization measures. However, to date, these measures have neither been collected nor consistently assessed for a wider application range. Therefore, in the study presented here a system for assessing the ecological and economic benefits of optimization measures was developed and applied. The assessment method utilized showed that optimization of district heating consumer substations and adding of a central buffer storage tank has a high optimization potential in comparison to intermittent operation strategy, which has a significantly lower optimization potential. From this information and the transferability data, a district heating operator can determine which optimization measure should be prioritized, which is shown at the end of the paper on an example case. UR - https://doi.org/10.1016/j.energy.2024.131226 Y1 - 2024 UR - https://doi.org/10.1016/j.energy.2024.131226 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-47196 SN - 1873-6785 SN - 0360-5442 VL - 2024 IS - 297 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bazzi, Ahmed A1 - El Hafdaoui, Hamza A1 - Khallaayoun, Ahmed A1 - Mehta, Kedar A1 - Ouazzani, Kamar A1 - Zörner, Wilfried T1 - Optimization Model of Hybrid Renewable Energy Generation for Electric Bus Charging Stations JF - Energies N2 - This paper introduces a comprehensive approach for sizing grid-connected hybrid renewable energy systems tailored for electric bus fleet operations. The study involves two main steps. First, a mathematical model that optimizes the configuration of such systems by considering daily electric bus consumption, solar irradiance, wind speed, and biomass potential is formulated. The model utilizes Pareto frontier multi-objective optimization to minimize the net present cost, the cost of energy, and greenhouse gas emissions. Second, the model is rigorously applied and tested in a real-world case study in Fez, Morocco, using HOMER Pro; the case study centers on the daily energy requirements of the buses, estimated at 2.5 megawatt hours per day, with a peak demand of 345 kilowatts. Two scenarios are explored, revealing a discernible trade-off dilemma between the full hybrid renewable energy scenario (Scenario 1) and the grid-connected hybrid renewable energy scenario (Scenario 2). In Scenario 2, the grid-connected hybrid renewable energy system demonstrates a notable 42.8% reduction in the net present cost, totaling USD 984,624. Similarly, the levelized cost of energy experiences a significant decrease, reaching approximately 0.08 USD/kWh, marking a 38.1% reduction. However, this apparent economic advantage is juxtaposed with a critical consideration—an increase in greenhouse gas emissions from null to 330,418 kg/year. UR - https://doi.org/10.3390/en17010053 KW - electric buses KW - HOMER KW - on-site renewable energy generation KW - sustainable transport KW - hybrid renewable energy generation KW - grid-connected renewable energy system KW - electric bus charging station Y1 - 2023 UR - https://doi.org/10.3390/en17010053 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-47109 SN - 1996-1073 VL - 17 IS - 1 PB - MDPI CY - Basel ER - TY - JOUR A1 - Bachseitz, Michael A1 - Sheryar, Muhammad A1 - Schmitt, David A1 - Summ, Thorsten A1 - Trinkl, Christoph A1 - Zörner, Wilfried T1 - PV-Optimized Heat Pump Control in Multi-Family Buildings Using a Reinforcement Learning Approach JF - Energies N2 - For the energy transition in the residential sector, heat pumps are a core technology for decarbonizing thermal energy production for space heating and domestic hot water. Electricity generation from on-site photovoltaic (PV) systems can also contribute to a carbon-neutral building stock. However, both will increase the stress on the electricity grid. This can be reduced by using appropriate control strategies to match electricity consumption and production. In recent years, artificial intelligence-based approaches such as reinforcement learning (RL) have become increasingly popular for energy-system management. However, the literature shows a lack of investigation of RL-based controllers for multi-family building energy systems, including an air source heat pump, thermal storage, and a PV system, although this is a common system configuration. Therefore, in this study, a model of such an energy system and RL-based controllers were developed and simulated with physical models and compared with conventional rule-based approaches. Four RL algorithms were investigated for two objectives, and finally, the soft actor–critic algorithm was selected for the annual simulations. The first objective, to maintain only the required temperatures in the thermal storage, could be achieved by the developed RL agent. However, the second objective, to additionally improve the PV self-consumption, was better achieved by the rule-based controller. Therefore, further research on the reward function, hyperparameters, and advanced methods, including long short-term memory layers, as well as a training for longer time periods than six days are suggested. UR - https://doi.org/10.3390/en17081908 KW - reinforcement learning KW - PV-optimization KW - heat pump KW - multi-family building KW - energy-management system Y1 - 2024 UR - https://doi.org/10.3390/en17081908 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-47361 SN - 1996-1073 VL - 17 IS - 8 PB - MDPI CY - Basel ER - TY - JOUR A1 - Summ, Thorsten A1 - Oyinlola, Muyiwa A1 - Khattak, Sanober A1 - Ehrenwirth, Mathias A1 - Trinkl, Christoph A1 - Zörner, Wilfried T1 - Towards maximum cost-effectiveness: multi-objective design optimisation of insulating glass flat-plate collectors JF - Applied Thermal Engineering N2 - A significant challenge in the advancement of solar thermal heating systems lies in the unexplored techno-economic potential of insulating glass flat-plate collectors. These collectors are constructed in accordance with the specifications of standard insulating glass units and have emerged over the past decade as a promising design concept for enhancing the cost-effectiveness of solar thermal systems. However, substantial findings regarding the techno-economic viability of their production are still pending. The aim of this paper is to optimise insulating glass collector designs for solar district heating applications by identifying key design parameters that maximise cost-effectiveness. This study employed a five-stage methodology. It included thermo-hydraulic collector modelling using MATLAB/Simscape and the CARNOT Toolbox. The model was validated against experimental performance tests. A Latin hypercube computational design with 250,000 samples was set up to train supervised machine learning metamodels and perform a multi-objective optimisation using an elitist genetic algorithm. The study identified the argon concentration, collector length, and width as critical parameters influencing efficiency. Larger, thinner collectors demonstrated superior performance due to reduced convective losses and increased aperture-to-surface ratios. The optimisation revealed that the insulating glass collectors could achieve a 7.7 percentage point increase in efficiency, a 19.4 % reduction in material cost, and a 14.5 % decrease in weight compared to market-available flat-plate collectors. However, the direct economic comparison was not considered strong in evidence due to a lack of economic data from technology providers. The most cost-effective designs featured an argon concentration of 99 %, sealing thickness of 31.2 mm, and a glazing thickness of 4.1 mm, and 4.5 mm, while collector length and width varied more significantly. The research findings indicate the techno-economic potential of insulating glass collectors, demonstrating their ability to outperform conventional flat-plate collectors in terms of cost-effectiveness and efficiency. Future studies should focus on producing and testing larger modules and incorporating production costs to fully realise their potential for solar district heating applications. This study provides valuable guidelines for IGU designers and producers aiming to develop cost-effective and efficient solar thermal collectors for district heating systems. UR - https://doi.org/10.1016/j.applthermaleng.2024.124594 Y1 - 2024 UR - https://doi.org/10.1016/j.applthermaleng.2024.124594 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-53618 SN - 1359-4311 VL - 2025 IS - 258 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Lwakatare, Bertha A1 - Vyavahare, Priyanka A1 - Mehta, Kedar A1 - Zörner, Wilfried T1 - Electrification Planning for Off-Grid Communities in Sub-Saharan Africa: Advancing Energy Access JF - Energies N2 - Sub-Saharan Africa, especially its rural areas, faces significant challenges in achieving universal electrification despite its abundant renewable energy resources. The region has the highest population without access to electricity, largely due to economic, infrastructural, and geographical barriers. Energy poverty is a critical issue that hinders sustainable development and exacerbates inequalities. Namibia’s sustainable energy policy aligns with the global Sustainable Development Goals (SDGs), particularly SDG 7, which aims to provide affordable and reliable modern energy access for all. The policy emphasizes mini-grids and decentralized power systems as key strategies for rural electrification. However, despite increased deployment of mini-grids, these solutions often struggle with long-term sustainability. This research explores cost-effective electrification strategies through scenario-based modeling to reduce energy poverty and expand energy access in Namibia’s rural communities, focusing on the existing mini-grids in Tsumkwe and Gam. Using a comprehensive methodology that incorporates HOMER Pro for mini-grid capacity expansion and MS Excel for evaluating main-grid extensions, this study aims to identify the most feasible and economical electrification solutions. The analysis compares electricity supply, total net present cost, and the levelized cost of electricity across these systems. The findings will offer insights into addressing energy poverty in Namibia and provide recommendations for sustainable and scalable rural electrification across Sub-Saharan Africa. UR - https://doi.org/10.3390/en17235994 KW - off-grid communities KW - grid extension KW - mini-grid expansion KW - rural electrification KW - Sub-Saharan Africa KW - Namibia Y1 - 2024 UR - https://doi.org/10.3390/en17235994 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-53771 SN - 1996-1073 VL - 17 IS - 23 PB - MDPI CY - Basel ER - TY - JOUR A1 - Mirzaqobulov, Jakhongirmirzo A1 - Mehta, Kedar A1 - Ilyas, Sana A1 - Salokhiddinov, Abdulkhakim T1 - The Role of Collector-Drainage Water in Sustainable Irrigation for Agriculture in the Developing World: An Experimental Study JF - World N2 - This study investigates the feasibility of using mineralized collector-drainage water (CDW) for irrigating maize crops on light gray soils in the Syrdarya region of Uzbekistan, an area facing severe water scarcity and soil salinity challenges. The research is particularly novel as it explores maize production in marginalized soils, a subject previously unexamined in this context. The experiment was designed as a three-factor factorial study with three replications, following the guidelines of the Uzbekistan Cotton Scientific Research Institute. Five irrigation treatments (Fresh Water, Fresh Water 70% vs. CDW 30%, Complex Method (Mixing with Specific Rules), CDW 70% vs. Fresh Water 30% (Mixing) and only CDW) were evaluated using an Alternate Furrow Irrigation system, incorporating various mixtures of fresh water and CDW to determine their effects on soil salinity, crop health and yield. The amount of irrigation water required was determined using a soil moisture balance model, with soil samples collected at multiple depths (0–100 cm) to monitor changes in moisture content and salinity. Salinity levels and soil health parameters such as alkalinity, chloride, sulfate and cation/anion balances were measured at different stages of crop growth. Data were collected over three growing seasons (3 years). An analysis of the data revealed that using CDW, even in mixtures with fresh water, can sustain crop production while managing soil salinity. Notably, irrigation methods such as Mixing 70–30 and the Complex Mixing Method effectively reduced freshwater dependency and maintained the crop yield without significantly increasing salinity. The results suggest that CDW could be a viable alternative water source in regions where traditional water resources are limited. The findings have significant implications for improving water use efficiency and agricultural productivity in areas facing similar environmental challenges. This research not only contributes to the broader understanding of sustainable irrigation practices in arid regions but also provides a scientific basis for the wider adoption of CDW in Uzbekistan, potentially enhancing food security and supporting long-term agricultural sustainability in the region. UR - https://doi.org/10.3390/world6010001 KW - water management KW - Central Asia KW - Uzbekistan KW - sustainable irrigation KW - SDGs KW - sustainable agriculture Y1 - 2024 UR - https://doi.org/10.3390/world6010001 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-55516 SN - 2673-4060 VL - 6 IS - 1 PB - MDPI CY - Basel ER - TY - JOUR A1 - Mehta, Kedar A1 - Zörner, Wilfried T1 - Cracking the code: mapping residential building energy performance in rural Central Asia through building typologies JF - SN Applied Sciences N2 - Buildings in rural Central Asia have unique characteristics as they were built during the Soviet era (during 1950–1960) without any energy efficiency measures. The special and aged building stock pose a crucial challenge on energy security and energy supply. However, accurate scientific data on their energy usage is lacking, highlighting a research gap about robust and validated methodology to determine the energy use of rural Central Asian buildings. In response to this need, this research paper proposes a set of generalised residential building typologies for rural Central Asia, with a focus on Kyrgyzstan. The study combines quantitative and qualitative methods, including household surveys, energy demand modelling, EnergyPlus simulations, and result validation. It derives energy-based building typologies from construction year and building envelope characteristics. Through numerous validated simulations, it was identified that the heat demand for rural Kyrgyz houses is 3–5 times here compared to European houses (250–400 kWh/m2). The study revealed the estimated heat demand for homes in rural Kyrgyzstan, indicating a significant potential for improving building energy efficiency in the region. These results can inform specific approaches, such as building renovation plans, energy certification, and renovation strategies. Furthermore, the validated methodology introduced offers opportunities for researchers in the field of building energy efficiency and can be applied to similar regions in Central Asia with comparable building stocks and climates. UR - https://doi.org/10.1007/s42452-023-05607-1 Y1 - 2023 UR - https://doi.org/10.1007/s42452-023-05607-1 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-41536 SN - 2523-3971 VL - 5 IS - 12 PB - Springer Nature CY - Cham ER - TY - JOUR A1 - Summ, Thorsten A1 - Oyinlola, Muyiwa A1 - Khattak, Sanober A1 - Trinkl, Christoph A1 - Zörner, Wilfried T1 - Statistical analysis of solar thermal collectors in the Solar Keymark Database JF - Sustainable Energy Technologies and Assessments N2 - Experimental, analytical, or numerical investigations are ordinarily conducted to reveal optimisation potential for solar thermal collectors. At the same time, the ‘Solar Keymark Database’ contains more than 2,000 test reports from certified laboratories featuring properties including thermal efficiency, dimensions, or optical properties. This dataset offers untapped potential for statistical analyses as an alternative optimisation approach. Hence, this paper aims to provide a) the first statistical findings of solar thermal collector properties listed in the Solar Keymark Database and b) insights into statistical relations between these properties. The key correlations observed from the analysis of flat-plate collectors were between efficiency and both gross height (R = 0.30) and gross area (R = 0.27). We concluded that preferable collector designs may be featured with larger area to height ratios. The analyses of evacuated tube collectors revealed a strong correlation between efficiency and transversal incidence angle modifier (R = -0.65) as a result from different tube spacing. It was noticeable that the quasi-dynamic test method reported significantly higher efficiencies (7.14 percentage points) for evacuated tube collectors, which should be carefully considered for future test procedures. Overall, the statistical analysis was in accordance with conventional bottom-up analyses and revealed insightful dependencies for the present collector data. UR - https://doi.org/10.1016/j.seta.2023.103581 Y1 - 2023 UR - https://doi.org/10.1016/j.seta.2023.103581 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-43981 SN - 2213-1396 VL - 2024 IS - 61 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Mehta, Kedar A1 - Zörner, Wilfried T1 - Crop selection in Agri-PV: international review based strategic decision-making model JF - Solar Compass N2 - Agri-Photovoltaics (Agri-PV) is well known for its dual land use, integrating solar energy generation with agricultural production. This not only optimizes land use but also enhances food and energy security. Since Agri-PV is closely linked with crop cultivation, it is not solely about energy generation but also requires careful consideration of crop suitability within Agri-PV installations. Despite its significance, there is limited information available to guide decision-making for crop selection in Agri-PV systems. Selecting suitable crops remains a complex challenge, as factors such as shading tolerance, water requirements, and economic viability vary across different geographical and climatic conditions. This study develops a novel, review-based decision support model for crop selection in Agri-PV systems, synthesizing international research and case studies to provide a structured framework for decision-making. The model is based on 12 main crop typologies and key parameters such as water use, shading adaptability, crop yield/economic potential, and space requirements, derived from 117 research articles and case studies from 25 countries. By leveraging insights from successful international implementations, the model provides a practical framework for policymakers, farmers, and energy planners to enhance the sustainability and efficiency of Agri-PV projects. Findings suggest that crop selection strategies must align with regional climate conditions and PV system design to maximize synergies between energy and food production. High-value crops that require less space and have higher shade tolerance are more suitable for small-scale or decentralized Agri-PV systems. Future research should focus on advanced modeling techniques, AI-driven optimization, and real-world pilot studies to further refine decision-making in Agri-PV deployment. This study contributes to the growing body of knowledge on Agri-PV systems by providing a novel crop suitability matrix for effective decision-making. UR - https://doi.org/10.1016/j.solcom.2025.100143 Y1 - 2025 UR - https://doi.org/10.1016/j.solcom.2025.100143 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-62476 SN - 2772-9400 VL - 2025 IS - 16 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Vannahme, Anna A1 - Patel, Dharmik A1 - Schmitt, David A1 - Summ, Thorsten A1 - Trinkl, Christoph A1 - Schrag, Tobias T1 - Technical and economic analysis of digitally controlled substations in local district heating networks JF - Energy N2 - Since the 1990s, there has been a noticeable increase in the establishment of local district heating networks in Germany, coinciding with the use of thermal energy from biogas and biomass facilities. Historically, the prioritization of economically efficient heat utilization was subdued due to favorable electricity feed-in tariffs. However, with the expiration of Renewable Energy Sources Act subsidies, operators shifted focus to the operational costs of district heating networks. This study aims to examine the effects of optimizing controllers and valves at district heating substations in single-family homes, utilizing two local district heating networks. The emphasis is on evaluating impacts on operating costs and determining whether the economic and energetic benefits justify implementation. Simulation studies in MATLAB/Simulink Simscape depict both consumers and district heating networks individually, without aggregation. In the most favorable scenario, investing in enhancing substation controllers in single-family homes is projected to yield returns after 13 years. Comprehensive optimization of all substation controls in single-family homes can potentially result in up to 9% savings in thermal energy demand due to reduced heat losses and a corresponding 9% reduction in electrical power consumption for the main pump. UR - https://doi.org/10.1016/j.energy.2024.133585 Y1 - 2024 UR - https://doi.org/10.1016/j.energy.2024.133585 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-52718 SN - 0360-5442 SN - 1873-6785 VL - 2024 IS - 312 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Tutunaru, Robin A1 - Bosch, Stephan A1 - Greßhake, Lukas A1 - Holzhammer, Uwe T1 - Ein Konzept für eine GIS-gestützte Visualisierung der spezifischen Anforderungen von regionalen Akteuren der Energiewende an die Landnutzung JF - AGIT: Journal für Angewandte Geoinformatik N2 - Für eine nachhaltige Energiewende werden Konzepte benötigt, welche die techno-ökonomische und sozial-ökologische Komplexität regionaler Standortentscheidungen für erneuerbare Energien (EE) visualisieren können. Dabei möchten wir die Ergebnisse mittels Geographischer Infor-mationssysteme (GIS) so visualisieren, dass sie von jedem Akteur nachvollzogen werden können und einen konstruktiven Austausch zur Wertigkeit bestimmter Flächen zwischen allen Akteuren erlauben. T2 - A Concept for a GIS-based Visualisation of the Specific Demands on Land Use at the Background of Regional Energy Transitions UR - https://doi.org/10.14627/537742005 Y1 - 2023 UR - https://doi.org/10.14627/537742005 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-62815 SN - 2509-713X SN - 2364-9283 VL - 2023 IS - 9 SP - 44 EP - 49 PB - Wichmann Verlag CY - Berlin ER - TY - CHAP A1 - Mast, Tanja A1 - Hümmer, Benedikt A1 - Holzhammer, Uwe T1 - Smart Markets als marktbasierte Ergänzung zum deutschen Engpassmanagement BT - Konzeptionierung anhand eines Modellbeispiels T2 - 17. Symposium Energieinnovation KW - netzdienliche Flexibilität KW - marktbasiertes Engpassmanagement KW - Smart Market Y1 - 2022 UR - https://www.tugraz.at/events/eninnov2022/nachlese/download-beitraege/stream-a/#c318498 PB - Technische Universität Graz CY - Graz ER - TY - JOUR A1 - Stöckl, Martin A1 - Holzhammer, Uwe T1 - Integration von Flexibilität in die Energieversorgung BT - Ein Aspekt zur Erreichung der Klimaziele und zur Stabilisierung der Energiekosten - Fallbeispiel Kühlhaus JF - Ernährung aktuell - der Lebensmittelbrief Y1 - 2024 SN - 1866-6787 VL - 35 IS - Mai/Juni SP - 46 EP - 47 PB - LID CY - Lampertheim ER - TY - CHAP A1 - Mast, Tanja A1 - Hümmer, Benedikt A1 - Holzhammer, Uwe T1 - Potential of Demand Side Management and Biogas Plants in regional market-based Congestion Management T2 - ENERDAY 15th Conference on Energy Economics and Technology "Creative Destruction? Disruptive innovation in times of Covid and an accelerated energy system transformation": Book of Abstracts KW - smart Market KW - grid congestion KW - biogas plants KW - demand side management Y1 - 2021 UR - https://tu-dresden.de/bu/wirtschaft/bwl/ee2/tagungen/enerday-archives SP - 22 EP - 23 PB - TU Dresden CY - Dresden ER - TY - JOUR A1 - Doepfert, Markus A1 - Chu, Jiahe A1 - Hamacher, Thomas T1 - HAMLET: A modular agent-based Python framework for energy markets and systems JF - SoftwareX N2 - HAMLET is an agent-based Python framework designed to model the intricate interactions between energy markets, systems, and stakeholders. Its modular architecture provides a flexible and adaptable platform for analyzing complex energy systems. With numerous pre-built templates for energy system components, HAMLET enables researchers to focus on their area of expertise without the need to develop the surrounding ecosystem from scratch. By integrating market and system dynamics, HAMLET supports diverse applications, including market design optimization, grid management, policy refinement, and energy management system development. HAMLET delivers detailed insights into the technical, economic, and social impacts of new system designs, addressing a critical gap in energy system modeling. UR - https://doi.org/10.1016/j.softx.2025.102346 Y1 - 2025 UR - https://doi.org/10.1016/j.softx.2025.102346 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-63428 SN - 2352-7110 VL - 2025 IS - 32 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Chaturvedi, Pushpendra Kr. A1 - Kumar, Nand A1 - Toftum, Jørn A1 - Andersen, Rune Korsholm A1 - Lamba, Ravita A1 - Mehta, Kedar T1 - Exploring influential parameters affecting residential building energy use: advancing energy efficiency through machine learning JF - Clean Technologies and Environmental Policy UR - https://doi.org/10.1007/s10098-025-03301-x Y1 - 2025 UR - https://doi.org/10.1007/s10098-025-03301-x SN - 1618-9558 VL - 27 IS - 11 SP - 6975 EP - 6996 PB - Springer CY - Berlin ER - TY - CHAP A1 - Reum, Tobias A1 - Natale, Christian A1 - Schmitt, David A1 - Dongellini, Matteo A1 - Naldi, Claudia A1 - Summ, Thorsten A1 - Morini, Gian Luca A1 - Schrag, Tobias ED - Zilio, Claudio ED - Busato, Filippo ED - Mazzarella, Livio ED - Noro, Marco T1 - Control Strategies for Active Regeneration in a Dual-Source Heat Pump T2 - Proceedings of the 15th REHVA HVAC World Congress - CLIMA 2025: Volume 1 UR - https://doi.org/10.1007/978-3-032-06806-4_55 Y1 - 2025 UR - https://doi.org/10.1007/978-3-032-06806-4_55 SN - 978-3-032-06806-4 SP - 564 EP - 574 PB - Springer CY - Cham ER - TY - CHAP A1 - Schmitt, David A1 - Reum, Tobias A1 - Summ, Thorsten A1 - Schrag, Tobias ED - Zilio, Claudio ED - Busato, Filippo ED - Mazzarella, Livio ED - Noro, Marco T1 - Comparison of Heat Pump Modelling Approaches for Predictive Controllers to Optimize the Efficiency of Modulating Air-Source Heat Pumps: A Case Study from South Germany T2 - Proceedings of the 15th REHVA HVAC World Congress - CLIMA 2025: Volume 1 UR - https://doi.org/10.1007/978-3-032-06806-4_59 Y1 - 2025 UR - https://doi.org/10.1007/978-3-032-06806-4_59 SN - 978-3-032-06806-4 SP - 611 EP - 620 PB - Springer CY - Cham ER - TY - JOUR A1 - Rouegui, Meryem A1 - Bellabair, Hind A1 - El Asli, Abdelghani A1 - Amar, Amine A1 - Zörner, Wilfried A1 - Rachidi, Fouad A1 - Lghoul, Rachid T1 - Bio-Methanization of Sheep Manure and Beet Waste in the Meknes–Fès Region, Morocco: Effects of Pretreatment and Machine Learning Applications for Biochemical Methane Potential Prediction JF - Recycling N2 - Sheep manure and beet waste (the uneatable leaf part of the beet) are promising feedstock for biogas production due to their abundance and organic richness. However, their high lignocellulosic content reduces anaerobic digestibility and controls methane yield. This study investigates the effect of various pretreatment strategies, namely physical, thermal, and combined physical–thermal methods, on the Biochemical Methane Potential (BMP) of sheep manure and beet waste. Batch anaerobic digestion experiments were conducted under mesophilic conditions, with BMP values recorded for each treatment. The highest BMP for sheep manure, 125 Nml CH4/g VS, was achieved using combined physical and thermal pretreatment. This approach enhanced methane production by 16%, 25%, and 60% compared to physical pretreatment (PP) alone, thermal pretreatment (TP) alone, and no pretreatment, respectively, while the one BMP for beet waste is 80 Nml CH4/g VS and obtained with thermal pretreatment. To predict BMP outcomes, three machine learning approaches are applied, namely Linear Regression (LM), Random Forest Regression (RFR), and Gradient Boosting Machine (GBM), using digestion time (N days), total solids (Ts), volatile solids (Vs), pretreatment type, and biomass type. The variance analysis confirmed that the interaction between pretreatment and biomass type significantly improved model performance. While diagnostic checks revealed non-linear patterns limiting the linear model, ensemble methods achieved stronger results. The RFR model explained 79.5% of the variance with a Root Mean Square Error (RMSE) of about 15.7, whereas the GBM model achieved the lowest RMSE of 5.05. GBM captures complex non-linear interactions. In addition, variable importance analyses identified digestion time, solid content, and pretreatment as the most influential factors for methane yield, with the combined chemical and physical pretreatment producing the highest biogas outputs. These findings underscore the potential of advanced machine learning models, particularly GBM (Gradient Boosting Machine), for optimizing anaerobic digestion strategies and maximizing biogas recovery from sheep manure and beet waste. UR - https://doi.org/10.3390/recycling10060213 Y1 - 2025 UR - https://doi.org/10.3390/recycling10060213 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-64862 SN - 2313-4321 VL - 10 IS - 6 PB - MDPI CY - Basel ER - TY - JOUR A1 - Mehta, Kedar A1 - Jain, Rushabh Bansilal A1 - Zörner, Wilfried T1 - Agrivoltaics Around the World: Potential, Technology, Crops and Policies to Address the Energy–Agriculture Nexus for Sustainable and Climate-Resilient Land Use JF - Energies N2 - The urgent pursuit of climate-resilient agriculture and clean energy systems, central to the Energy–Agriculture Nexus and the UN Sustainable Development Goals, has accelerated global interest in agrivoltaic (Agri-PV) technologies. This paper presents a global systematic review and meta-analysis of 160 peer-reviewed studies, structured through a five-stage thematic synthesis: (1) mapping global and regional Agri-PV deployment and potential, (2) analyzing system design and modeling methodologies, (3) evaluating crop suitability under partial shading, (4) reviewing enabling policies and regulatory frameworks, and (5) assessing techno-economic feasibility and investment barriers. Results reveal that Europe and Asia lead Agri-PV development, driven by incentive-based policies and national tenders, while limited regulatory clarity and high capital costs constrain wider adoption. Despite technological progress, no integrated model fully captures the coupled energy, water, and crop dynamics essential for holistic assessment. Strengthening economic valuation, policy coherence, and standardized modeling approaches will be critical to scale Agri-PV systems as a cornerstone of sustainable and climate-resilient land use. UR - https://doi.org/10.3390/en18246417 Y1 - 2025 UR - https://doi.org/10.3390/en18246417 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-65288 SN - 1996-1073 VL - 18 IS - 24 PB - MDPI CY - Basel ER - TY - JOUR A1 - Mehta, Kedar A1 - Lwakatare, Bertha A1 - Zörner, Wilfried A1 - Ehrenwirth, Mathias T1 - Mini-grid performance in Sub-Saharan Africa: case studies from Tsumkwe and Gam, Namibia JF - Sustainable Energy Research N2 - This paper investigates the performance analysis and operational challenges of mini-grids in Sub-Saharan Africa, focusing on the Tsumkwe and Gam mini-grids, the only officially recognized mini-grids in Namibia. The study addresses a critical gap in understanding mini-grid efficiency, technical difficulties, and future potential. The key research questions focus on assessing mini-grid performance, identifying technical and operational challenges, quantifying the relationship between electricity demand and supply, and providing recommendations for enhancing rural electrification through mini-grids. These insights are crucial for evaluating the effectiveness of mini-grids in the African context and understanding their role in advancing rural electrification. By using a mixed-method approach, the research combines quantitative and qualitative data to offer a comprehensive analysis of these two mini-grid systems of Namibia. The data collected from 2017 to 2022 include metrics on energy supply, consumption, photovoltaic generation, community load, and meteorological conditions. Qualitative insights were gathered through field visits, surveys, and interviews with mini-grid operators, allowing for a thorough examination of community perspectives, operational issues, and technical performance. The findings reveal that the Tsumkwe mini-grid has seen a decline in efficiency due to maintenance problems and battery overheating, while the Gam mini-grid, initially oversized, now struggles with increased demand and new connections. This study provides the first detailed technical insights, identifies consumer archetypes, and evaluates the energy dynamics of mini-grids in Namibia. Recommendations include improved maintenance protocols, advanced battery management, and enhanced data monitoring. By analyzing Tsumkwe and Gam, this paper offers valuable lessons for mini-grid development in Sub-Saharan Africa, stressing the need for continuous evaluation and strategic improvements to achieve sustainable rural electrification. UR - https://doi.org/10.1186/s40807-025-00174-y Y1 - 2025 UR - https://doi.org/10.1186/s40807-025-00174-y UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-65316 SN - 2731-9237 VL - 12 IS - 1 PB - SpringerOpen CY - Singapore ER - TY - JOUR A1 - Chaturvedi, Pushpendra Kr. A1 - Kumar, Nand A1 - Lamba, Ravita A1 - Mehta, Kedar T1 - Multi-objective optimization of glazing and shading configurations for visual, thermal, and energy performance of cooling dominant climatic regions of India JF - Clean Technologies and Environmental Policy UR - https://doi.org/10.1007/s10098-024-03114-4 Y1 - 2024 UR - https://doi.org/10.1007/s10098-024-03114-4 SN - 1618-9558 VL - 27 IS - 9 SP - 4909 EP - 4932 PB - Springer CY - Berlin ER - TY - JOUR A1 - Mehta, Kedar A1 - Betz, Florian T1 - Agri-photovoltaics in India: Geospatial suitability for sustainable water–energy–food nexus solutions JF - Energy for Sustainable Development UR - https://doi.org/10.1016/j.esd.2025.101915 Y1 - 2025 UR - https://doi.org/10.1016/j.esd.2025.101915 SN - 2352-4669 VL - 2026 IS - 91 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Mehta, Kedar A1 - Ehrenwirth, Mathias A1 - Zörner, Wilfried A1 - Greenough, Richard T1 - Need of energy transition at roof of the world BT - Correlative approach to interpret energy identity of high-altitude Central Asian communities JF - Energy for Sustainable Development UR - https://doi.org/10.1016/j.esd.2023.101271 Y1 - 2023 UR - https://doi.org/10.1016/j.esd.2023.101271 SN - 2352-4669 SN - 0973-0826 VL - 2023 IS - 76 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Idda, Johannes A1 - Selleneit, Volker A1 - Holzhammer, Uwe T1 - Hochflexible Biomethan-BHKW-Anlagen und der Einfluss eines Biomethanspeichers auf den möglichen Biogaspreis für Post-EEG-Biogasanlagen T2 - Biogas in der Landwirtschaft – Stand und Perspektiven: FNR/KTBL-Kongress am 8. und 9. September 2025 Y1 - 2025 SP - 94 EP - 101 PB - KTBL CY - Darmstadt ER - TY - JOUR A1 - Mehta, Kedar A1 - Lamba, Ravita A1 - Sinha, Sunanda A1 - Kumar, Nand T1 - BIPV in India: Opportunities, challenges, and pathways for urban planning and smart cities JF - Solar Compass N2 - As India urbanizes rapidly, sustainable energy solutions have become a priority to meet rising energy demands and mitigate environmental impacts. Building-Integrated Photovoltaics (BIPV) offer a promising approach to harness solar energy within urban infrastructure, transforming buildings into renewable energy assets. Unlike conventional rooftop PV systems, BIPV maximizes urban space utilization while enhancing architectural aesthetics and energy efficiency. However, the adoption of BIPV in India remains limited due to factors such as regulatory barriers, lack of standardized designs, and high initial costs. This study uses SWOT (Strengths, Weaknesses, Opportunities, Threats) and TOWS (Threats, Opportunities, Weaknesses, Strengths) analyses to assess the potential, opportunities, and challenges of BIPV in India’s urban planning. It then discusses policy implications and offers practical recommendations for implementation in Indian cities. Key findings of this study indicate that BIPV adoption in India can significantly contribute to urban sustainability by reducing carbon emissions, improving energy self-sufficiency, and lowering long-term operational costs. The SWOT and TOWS analysis reveal that while BIPV presents opportunities for smart urban integration, challenges such as high initial investments and lack of awareness must be addressed through targeted policies and incentives. Additionally, global case studies highlight successful BIPV implementations, providing valuable lessons for India’s urban planning strategies. UR - https://doi.org/10.1016/j.solcom.2025.100133 Y1 - 2025 UR - https://doi.org/10.1016/j.solcom.2025.100133 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-61824 SN - 2772-9400 VL - 2025 IS - 15 PB - Elsevier CY - Amsterdam ER -