@inproceedings{ReumNataleSchmittetal.2025, author = {Reum, Tobias and Natale, Christian and Schmitt, David and Dongellini, Matteo and Naldi, Claudia and Summ, Thorsten and Morini, Gian Luca and Schrag, Tobias}, title = {Control Strategies for Active Regeneration in a Dual-Source Heat Pump}, booktitle = {Proceedings of the 15th REHVA HVAC World Congress - CLIMA 2025: Volume 1}, editor = {Zilio, Claudio and Busato, Filippo and Mazzarella, Livio and Noro, Marco}, publisher = {Springer}, address = {Cham}, isbn = {978-3-032-06806-4}, doi = {https://doi.org/10.1007/978-3-032-06806-4_55}, pages = {564 -- 574}, year = {2025}, language = {en} } @inproceedings{SchmittReumSummetal.2025, author = {Schmitt, David and Reum, Tobias and Summ, Thorsten and Schrag, Tobias}, title = {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}, booktitle = {Proceedings of the 15th REHVA HVAC World Congress - CLIMA 2025: Volume 1}, editor = {Zilio, Claudio and Busato, Filippo and Mazzarella, Livio and Noro, Marco}, publisher = {Springer}, address = {Cham}, isbn = {978-3-032-06806-4}, doi = {https://doi.org/10.1007/978-3-032-06806-4_59}, pages = {611 -- 620}, year = {2025}, language = {en} } @article{RoueguiBellabairElAslietal.2025, author = {Rouegui, Meryem and Bellabair, Hind and El Asli, Abdelghani and Amar, Amine and Z{\"o}rner, Wilfried and Rachidi, Fouad and Lghoul, Rachid}, title = {Bio-Methanization of Sheep Manure and Beet Waste in the Meknes-F{\`e}s Region, Morocco: Effects of Pretreatment and Machine Learning Applications for Biochemical Methane Potential Prediction}, volume = {10}, pages = {213}, journal = {Recycling}, number = {6}, publisher = {MDPI}, address = {Basel}, issn = {2313-4321}, doi = {https://doi.org/10.3390/recycling10060213}, year = {2025}, abstract = {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.}, language = {en} } @article{MehtaJainZoerner2025, author = {Mehta, Kedar and Jain, Rushabh Bansilal and Z{\"o}rner, Wilfried}, title = {Agrivoltaics Around the World: Potential, Technology, Crops and Policies to Address the Energy-Agriculture Nexus for Sustainable and Climate-Resilient Land Use}, volume = {18}, pages = {6417}, journal = {Energies}, number = {24}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en18246417}, year = {2025}, abstract = {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.}, language = {en} } @article{MehtaLwakatareZoerneretal.2025, author = {Mehta, Kedar and Lwakatare, Bertha and Z{\"o}rner, Wilfried and Ehrenwirth, Mathias}, title = {Mini-grid performance in Sub-Saharan Africa: case studies from Tsumkwe and Gam, Namibia}, volume = {12}, pages = {30}, journal = {Sustainable Energy Research}, number = {1}, publisher = {SpringerOpen}, address = {Singapore}, issn = {2731-9237}, doi = {https://doi.org/10.1186/s40807-025-00174-y}, year = {2025}, abstract = {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.}, language = {en} } @article{ChaturvediKumarLambaetal.2024, author = {Chaturvedi, Pushpendra Kr. and Kumar, Nand and Lamba, Ravita and Mehta, Kedar}, title = {Multi-objective optimization of glazing and shading configurations for visual, thermal, and energy performance of cooling dominant climatic regions of India}, volume = {27}, journal = {Clean Technologies and Environmental Policy}, number = {9}, publisher = {Springer}, address = {Berlin}, issn = {1618-9558}, doi = {https://doi.org/10.1007/s10098-024-03114-4}, pages = {4909 -- 4932}, year = {2024}, language = {en} } @article{MehtaBetz2025, author = {Mehta, Kedar and Betz, Florian}, title = {Agri-photovoltaics in India: Geospatial suitability for sustainable water-energy-food nexus solutions}, volume = {2026}, pages = {101915}, journal = {Energy for Sustainable Development}, number = {91}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2352-4669}, doi = {https://doi.org/10.1016/j.esd.2025.101915}, year = {2025}, language = {en} } @article{MehtaEhrenwirthZoerneretal.2023, author = {Mehta, Kedar and Ehrenwirth, Mathias and Z{\"o}rner, Wilfried and Greenough, Richard}, title = {Need of energy transition at roof of the world}, volume = {2023}, pages = {101271}, journal = {Energy for Sustainable Development}, subtitle = {Correlative approach to interpret energy identity of high-altitude Central Asian communities}, number = {76}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2352-4669}, doi = {https://doi.org/10.1016/j.esd.2023.101271}, year = {2023}, language = {en} } @inproceedings{IddaSelleneitHolzhammer2025, author = {Idda, Johannes and Selleneit, Volker and Holzhammer, Uwe}, title = {Hochflexible Biomethan-BHKW-Anlagen und der Einfluss eines Biomethanspeichers auf den m{\"o}glichen Biogaspreis f{\"u}r Post-EEG-Biogasanlagen}, booktitle = {Biogas in der Landwirtschaft - Stand und Perspektiven: FNR/KTBL-Kongress am 8. und 9. September 2025}, publisher = {KTBL}, address = {Darmstadt}, pages = {94 -- 101}, year = {2025}, language = {de} } @article{MehtaLambaSinhaetal.2025, author = {Mehta, Kedar and Lamba, Ravita and Sinha, Sunanda and Kumar, Nand}, title = {BIPV in India: Opportunities, challenges, and pathways for urban planning and smart cities}, volume = {2025}, pages = {100133}, journal = {Solar Compass}, number = {15}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2772-9400}, doi = {https://doi.org/10.1016/j.solcom.2025.100133}, year = {2025}, abstract = {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.}, language = {en} } @article{BottDresselBayer2020, author = {Bott, Christoph and Dressel, Ingo and Bayer, Peter}, title = {Paraffin wax as self-sealing insulation material of seasonal sensible heat storage systems—A laboratory study}, volume = {15}, pages = {e0236056}, journal = {PLOS ONE}, number = {7}, publisher = {PLOS}, address = {San Francisco}, issn = {1932-6203}, doi = {https://doi.org/10.1371/journal.pone.0236056}, year = {2020}, abstract = {Seasonal heat storage is considered as one of the key elements on the path to a low-emission economy. Embedded in local district heating networks, they raise the share of renewable energies and balance out highly fluctuating supplies of e.g. solar systems or windmills. The technology of seasonal heat storage can be described as almost technically mature, with well-established concepts and some systems being in operation for a considerable time. Nevertheless, the operating experience gained to date also revealed two critical problems. On the one hand, even smallest leakages in sealing foils led to irreparable breakdowns. On the other hand, heat loss in the marginal areas was revealed as a key deficiency, preventing the technology from advancing towards global marketability. This study presents an experimental approach to address these two key issues in the field of seasonal energy storage. Two small-scale laboratory tests were carried out to test paraffin wax as a completely novel component in the marginal area of seasonal storages. This is based on two material properties: As hydrophobic and mobile medium, the warmed and molten paraffin should actively seal the fissures and holes in the event of leakage. Additionally, the latent heat storage properties of the paraffin wax should increase the systems' total storage capacity and reduce lateral heat losses via its low thermal conductivity. With retardation periods from 2.5 to 4 hours, the results show an effective phase change effect of the paraffin wax, which reduces energy losses and allows to buffer short-term, intensive loading and unloading processes. By storing up to 138 kJ/kg energy in the paraffin wax, increased capacities of application-scale pit storages by up to 40.70 MWh are to be expected. Additionally, the self-healing features could be successfully demonstrated: With only small losses of between 1.5 and 17\%, the paraffin wax effectively sealed artificially incised leaks. Thereby, the mechanism was most effective for local defects. Following these positive demonstrations of feasibility, technical design questions still remain, which concern prevention of deformation of the paraffin wax. Once solved, this new component can then provide a path for further optimization of seasonal heat storage technologies.}, language = {en} } @inproceedings{Mehta2026, author = {Mehta, Kedar}, title = {AI and ML Based Energy Management in Smart Grids with Renewable Integration}, booktitle = {Digital Technologies and Applications: Proceedings of ICDTA'25, Ifrane, Morocco. Volume 1}, editor = {Motahhir, Saad and Bossoufi, Badre and Guerrero, Josep M.}, publisher = {Springer}, address = {Cham}, isbn = {978-3-032-07718-9}, doi = {https://doi.org/10.1007/978-3-032-07718-9_38}, pages = {453 -- 463}, year = {2026}, language = {en} } @unpublished{MuellerSchmittBottetal.2026, author = {M{\"u}ller, Simon Nikolaus and Schmitt, David and Bott, Christoph and Akbar, Shariq and Bayer, Peter and Schrag, Tobias}, title = {Operating thermal source networks - How supply temperature and ground exchange shape performance}, titleParent = {SSRN}, publisher = {Elsevier}, address = {Amsterdam}, doi = {http://dx.doi.org/10.2139/ssrn.6034530}, year = {2026}, language = {en} } @inproceedings{ReumSchmittSummetal.2024, author = {Reum, Tobias and Schmitt, David and Summ, Thorsten and Schrag, Tobias}, title = {Energetic Potential of Parallel Operation of Two Heat Sources in a Dual-Source Heat Pump}, booktitle = {International Sustainable Energy Conference - Proceedings}, editor = {Fink, Christian and Brunner, Christoph}, publisher = {TIB Open Publishing}, address = {Hannover}, issn = {2976-2030}, doi = {https://doi.org/10.52825/isec.v1i.1158}, year = {2024}, abstract = {Dual-source heat pumps can mitigate disadvantages of single source heat pumps: They have fewer geological requirements compared to ground-source heat pumps while having higher efficiencies compared to air-source heat pumps. Parallel operation of two heat sources can also make electric heaters for peak loads obsolete, leading to economic benefits in the operational costs. Parallel operation has not been analysed thoroughly at different evaporation temperature gradients. To address this gap in research, four possible interconnections of two heat sources were analysed using a refrigerant cycle simulation, two with similar and two with separate evaporation pressures. The energetic potential of each interconnection is evaluated and compared to single source operation with an air-source and a ground-source heat pump. The results showed that only the interconnections with separate evaporation pressure allowed significant reduction in evaporation power from the ground source. As expected, the efficiency - compared to single air-source operation - increased for all parallel interconnections but decreased compared to ground-source operation. Efficient peak load coverage with small ground-source collectors therefore requires a more complex interconnection of completely split evaporator branches at different evaporation pressures. While the efficiency and heating power compared to single ground-source operation decreased slightly (by 4\% and 6\%, respectively), the power load on the GSHX and ASHX reduced to about 54\% and 66\% compared to the corresponding single-source operation, respectively. This allows high efficiency at reduced GSHX size and ASHX noise emission. Additionally, this interconnection also allows increased flexibility for improved heat source management.}, language = {en} } @inproceedings{MuellerStrobelFaigletal.2024, author = {M{\"u}ller, Simon Nikolaus and Strobel, Rainer and Faigl, Markus and Schrag, Tobias}, title = {Analysis of Industrial 5GDHC System in Ingolstadt}, booktitle = {International Sustainable Energy Conference - Proceedings}, subtitle = {A Step Towards CO2-Neutral Industry}, editor = {Fink, Christian and Brunner, Christoph}, publisher = {TIB Open Publishing}, address = {Hannover}, issn = {2976-2030}, doi = {https://doi.org/10.52825/isec.v1i.1152}, year = {2024}, abstract = {This study comprehensively examines the technical manifestation and planning process for a shared thermal energy network at a 75-hectare industrial area in Ingolstadt. Unlike traditional systems, this (5GDHC) network showcases a smart integration of energy flows across 70 buildings with a yearly heating demand of around 17 GWh and a yearly cooling demand of around 35 GWh. The network spans over 9,100 meters of piping with diameters up to 800 mm. With thermal power from various sources including 1.8 MW waste heat from a data centre and potential for 10 MW from the Danube River, the system epitomizes a dynamic balance of heating and cooling demands. The paper itself examines the planning process of the system and encompasses topics such as defining energy requirements and load profiles, assessing potential energy sources and sinks for enhanced system efficiency, and analysing pipe and network design. Through this investigation, the study provides valuable insights towards a methodology to facilitate the successful implementation of future industrial 5GDHC systems, furthering the cause of sustainable energy.}, language = {en} } @article{EmbergerNairLichteneggeretal.2025, author = {Emberger, Lukas and Nair, Gireesh and Lichtenegger, Klaus and Moser, Maria and Summ, Thorsten and Natiesta, Thomas and Fan, Jianhua and Wang, Pengcheng and Unterberger, Viktor and Ohnewein, Philip}, title = {Open data in the solar thermal community: Status, barriers, and opportunities}, volume = {2025}, pages = {100114}, journal = {Solar Energy Advances}, number = {5}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2667-1131}, doi = {https://doi.org/10.1016/j.seja.2025.100114}, year = {2025}, abstract = {Open data in the renewable energy sector could contribute to a greener future and reduce carbon emissions. This study investigates existing open datasets in the solar thermal domain, challenges in publishing and using open data and its potential impact. The results support the common belief that open data is useful, offering considerable benefits for data re-users and the solar thermal community. While substantial open data in the solar thermal domain already exists, some datasets like plant statistics and cost data are hard to utilize due to licensing, accessibility, and quality issues. The study shows that data owners benefit less from publishing data compared to data re-users and service providers. While data sharing seems appealing to data owners, several barriers discourage data sharing. Suggestions to promote the use and publications of open data in solar thermal domain are discussed.}, language = {en} } @article{JamesKillingerMutangaetal.2025, author = {James, Stuart Daniel and Killinger, Markus and Mutanga, Chiedza Ngonidzashe and Pirard, Romain and Einax, Mario and Huber, Matthias and Bader, Tobias}, title = {The hybrid renewable energy community approach (HyRECA): Synergising electricity access with bush encroachment mitigation in rural Southern Africa}, volume = {2026}, pages = {100136}, journal = {Renewable and Sustainable Energy Transition}, number = {9}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2667-095X}, doi = {https://doi.org/10.1016/j.rset.2025.100136}, year = {2025}, abstract = {Rural electrification and bush encroachment in Southern Africa have long been studied separately. Research shows that hybrid renewable energy systems (HRES) offer viable solutions for off-grid communities, and bush encroachment mitigation is widely recognised as an ecological priority. Using Jamataka, Botswana, as a case study, this study integrates both, asking under which conditions encroacher bush-based HRES are economically viable, which electricity access levels local populations can afford, and whether biomass utilisation contributes to mitigation. Findings indicate strong potential for bush-based HRES in off-grid areas, but competitiveness declines where low-cost grid electricity is available. Economic viability is examined through levelised cost of electricity (LCOE) across alternative HRES configurations. HOMER Pro® simulations indicate PV/biomass/battery systems are most cost-effective off-grid, achieving 100 \% renewable fractions, near zero CO₂ emissions, and LCOE of 0.246 \$/kWh. In grid-connected contexts without feed-in, PV/diesel/grid combinations dominate (LCOE 0.117 \$/kWh) due to low tariffs, but with higher emissions. A novel affordability analysis using household willingness to pay and the World Bank Multi-Tier Framework indicates that all households reach at least Tier 3 electricity access under grid-connected systems and >70 \% off-grid, supporting household-use of medium-power appliances. Sustainable biomass extraction clears ∼12 ha annually (∼120 t) in Jamataka, aiding bush encroachment mitigation. Upscaling indicates potential to electrify 1.35 million people in >900 bush-encroached villages across Botswana, Namibia, and South Africa, using <1 \% of encroached land - highlighting significant untapped potential. Future research should validate findings through geospatial modelling with high-resolution biomass data and spatially sensitive biomass cost models for region-wide planning.}, language = {en} } @unpublished{JamesKillingerMutangaetal.2025, author = {James, Stuart Daniel and Killinger, Markus and Mutanga, Chiedza Ngonidzashe and Pirard, Romain and Einax, Mario and Huber, Matthias and Bader, Tobias}, title = {The Hybrid Renewable Energy Community Approach (HyRECA): Synergising energy access, economic development, and ecosystem restoration in rural Southern Africa}, titleParent = {SSRN}, publisher = {Elsevier}, address = {Amsterdam}, doi = {https://dx.doi.org/10.2139/ssrn.5294413}, year = {2025}, language = {en} } @article{NgetunyBaldaufZoerner2026, author = {Ngetuny, Joshua Kiplagat and Baldauf, Tobias and Z{\"o}rner, Wilfried}, title = {Evaluating Feedstock Pretreatment Methods to Unlock Co-Digestion in Small-Scale Biogas Systems: A Multi-Criteria Approach to System Integration and Decision Making}, volume = {19}, pages = {1303}, journal = {Energies}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en19051303}, year = {2026}, abstract = {Small-scale biogas plants in developing countries present a viable alternative to traditional polluting energy sources, particularly in rural and underserved communities. These systems typically rely on locally sourced livestock manure; however, inconsistent supply often results in underfeeding, reduced biogas production, and, in many cases, system abandonment. Co-digestion with crop residues presents a promising strategy to enhance feedstock availability and system resilience. However, the recalcitrant nature of lignocellulosic biomass and limited access to suitable pretreatment technologies have constrained its adoption. This paper evaluates feasible pretreatment methods for integrating crop residues, especially straw, into small-scale biogas systems. Using the Analytic Hierarchy Process (AHP), pretreatment methods are assessed based on five criteria: (i) technology simplicity, (ii) energy requirements, (iii) capital and operational costs, (iv) effectiveness, and (v) environmental impact. The analysis identifies microbial pretreatment using the liquid fraction of digestate, combined with mechanical size reduction, as the most suitable approach for small-scale implementation, utilizing low-cost, simplified mechanical devices adaptable to various crop residues with minimal energy input. A conceptual design of a demonstration plant is proposed to validate this integrated pretreatment approach and assess its impact on biogas yield, system performance, and technology adoption. The design incorporates an on-site digestate separation unit to supply microbial inoculum and emphasizes simplicity and cost-effectiveness in material handling and energy use. Pilot trials are proposed to evaluate key performance indicators, including specific methane yield (LCH4/gVS added), volatile solids reduction (\%), and methane content increase (\%), ensuring evidence-based adoption and practical applicability of the design.}, language = {en} } @article{NgetunyBaldaufZoerner2025, author = {Ngetuny, Joshua Kiplagat and Baldauf, Tobias and Z{\"o}rner, Wilfried}, title = {Optimizing Feedstock Selection for Sustainable Small-Scale Biogas Systems Using the Analytic Hierarchy Process}, volume = {18}, pages = {1739}, journal = {Energies}, number = {7}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en18071739}, year = {2025}, abstract = {Small-scale biogas systems can play a pivotal role in sustainable energy provision, particularly in developing countries. However, their dependence on livestock manure as the only feedstock poses challenges to their adoption and long-term viability. This often leads to insufficient biogas production and plant abandonment. This study proposes co-digestion of livestock manure with other farm residues to enhance the technical sustainability of small-scale biogas systems by ensuring adequate and consistent biogas production throughout the plant's lifespan, minimizing the risks associated with reliance on a single feedstock. A novel feedstock selection approach is developed using the Analytic Hierarchy Process (AHP), a multicriteria decision-making method, to prioritize feedstocks based on adequacy, supply consistency, and logistical ease. AHP is chosen due to its capability to handle both quantitative and qualitative evaluation criteria. This approach is applied to the F{\`e}s-Mekn{\`e}s region of Morocco, which offers abundant livestock and crop residues alongside product utilization pathways. The prioritization and ranking of the potential feedstocks identified in the region reveals cattle manure as the top-ranked feedstock due to its consistent supply and ease of collection, followed by straw, valued for its storability and nutrient stability. Sheep, horse, and chicken manure ranked third, fourth, and fifth, respectively, while household food waste and fruit and vegetable residues, limited by seasonality and perishability, were ranked lower. Based on these findings, co-digestion of cattle manure and straw is proposed as a sustainable strategy for small-scale biogas plants in F{\`e}s-Mekn{\`e}s, addressing feedstock shortages, enhancing biogas production, and reducing plant abandonment. This approach strengthens technical sustainability and promotes the broader adoption of biogas technologies in developing countries.}, language = {en} }