TY - JOUR A1 - Rieke, Christian A1 - Stollenwerk, Dominik A1 - Dahmen, Markus A1 - Pieper, Martin T1 - Modeling and optimization of a biogas plant for a demand-driven energy supply JF - Energy N2 - Due to the Renewable Energy Act, in Germany it is planned to increase the amount of renewable energy carriers up to 60%. One of the main problems is the fluctuating supply of wind and solar energy. Here biogas plants provide a solution, because a demand-driven supply is possible. Before running such a plant, it is necessary to simulate and optimize the process. This paper provides a new model of a biogas plant, which is as accurate as the standard ADM1 model. The advantage compared to ADM1 is that it is based on only four parameters compared to 28. Applying this model, an optimization was installed, which allows a demand-driven supply by biogas plants. Finally the results are confirmed by several experiments and measurements with a real test plant. Y1 - 2018 U6 - https://doi.org/10.1016/j.energy.2017.12.073 SN - 0360-5442 VL - 145 SP - 657 EP - 664 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Dotzauer, Martin A1 - Pfeiffer, Diana A1 - Lauer, Markus A1 - Pohl, Marcel A1 - Mauky, Eric A1 - Bär, Katharina A1 - Sonnleitner, Matthias A1 - Zörner, Wilfried A1 - Hudde, Jessica A1 - Schwarz, Björn A1 - Faßauer, Burkhardt A1 - Dahmen, Markus A1 - Rieke, Christian A1 - Herbert, Johannes A1 - Thrän, Daniela T1 - How to measure flexibility – Performance indicators for demand driven power generation from biogas plants JF - Renewable Energy Y1 - 2019 U6 - https://doi.org/10.1016/j.renene.2018.10.021 SN - 0960-1481 SP - 135 EP - 146 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Breitbach, Gerd A1 - Alexopoulos, Spiros A1 - May, Martin A1 - Teixeira Boura, Cristiano José A1 - Herrmann, Ulf T1 - Analysis of volumetric solar radiation absorbers made of wire meshes T2 - AIP Conference Proceedings Y1 - 2019 U6 - https://doi.org/10.1063/1.5117521 SN - 0094243X VL - 2126 SP - 030009-1 EP - 030009-6 ER - TY - CHAP A1 - Mahdi, Zahra A1 - Rendón, Carlos A1 - Schwager, Christian A1 - Teixeira Boura, Cristiano José A1 - Herrmann, Ulf T1 - Novel concept for indirect solar-heated methane reforming T2 - AIP Conference Proceedings Y1 - 2019 U6 - https://doi.org/10.1063/1.5117694 SN - 0094-243X VL - 2126 SP - 180014-1 EP - 180014-7 PB - AIP Publishing CY - Melville, NY ER - TY - CHAP A1 - May, Martin A1 - Breitbach, Gerd A1 - Alexopoulos, Spiros A1 - Latzke, Markus A1 - Bäumer, Klaus A1 - Uhlig, Ralf A1 - Söhn, Matthias A1 - Teixeira Boura, Cristiano José A1 - Herrmann, Ulf T1 - Experimental facility for investigations of wire mesh absorbers for pressurized gases T2 - AIP Conference Proceedings Y1 - 2019 U6 - https://doi.org/10.1063/1.5117547 SN - 0094243X VL - 2126 SP - 030035-1 EP - 030035-9 ER - TY - CHAP A1 - Sattler, Johannes, Christoph A1 - Alexopoulos, Spiros A1 - Caminos, Ricardo Alexander Chico A1 - Mitchell, John C. A1 - Ruiz, Victor C. A1 - Kalogirou, Soteris A1 - Ktistis, Panayiotis K. A1 - Teixeira Boura, Cristiano José A1 - Herrmann, Ulf T1 - Dynamic simulation model of a parabolic trough collector system with concrete thermal energy storage for process steam generation T2 - AIP Conference Proceedings Y1 - 2019 U6 - https://doi.org/10.1063/1.5117663 SN - 0094243X VL - 2126 SP - 150007-1 EP - 150007-8 ER - TY - JOUR A1 - Edip, K. A1 - Sesov, V. A1 - Butenweg, Christoph A1 - Bojadjieva, J. T1 - Development of coupled numerical model for simulation of multiphase soil JF - Computers and Geotechnics N2 - In this paper, a coupled multiphase model considering both non-linearities of water retention curves and solid state modeling is proposed. The solid displacements and the pressures of both water and air phases are unknowns of the proposed model. The finite element method is used to solve the governing differential equations. The proposed method is demonstrated through simulation of seepage test and partially consolidation problem. Then, implementation of the model is done by using hypoplasticity for the solid phase and analyzing the fully saturated triaxial experiments. In integration of the constitutive law error controlling is improved and comparisons done accordingly. In this work, the advantages and limitations of the numerical model are discussed. Y1 - 2018 U6 - https://doi.org/10.1016/j.compgeo.2017.08.016 SN - 0266-352X VL - 96 SP - 118 EP - 131 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Rupp, Matthias A1 - Rieke, Christian A1 - Handschuh, Nils A1 - Kuperjans, Isabel T1 - Economic and ecological optimization of electric bus charging considering variable electricity prices and CO₂eq intensities JF - Transportation Research Part D: Transport and Environment N2 - In many cities, diesel buses are being replaced by electric buses with the aim of reducing local emissions and thus improving air quality. The protection of the environment and the health of the population is the highest priority of our society. For the transport companies that operate these buses, not only ecological issues but also economic issues are of great importance. Due to the high purchase costs of electric buses compared to conventional buses, operators are forced to use electric vehicles in a targeted manner in order to ensure amortization over the service life of the vehicles. A compromise between ecology and economy must be found in order to both protect the environment and ensure economical operation of the buses. In this study, we present a new methodology for optimizing the vehicles’ charging time as a function of the parameters CO₂eq emissions and electricity costs. Based on recorded driving profiles in daily bus operation, the energy demands of conventional and electric buses are calculated for the passenger transportation in the city of Aachen in 2017. Different charging scenarios are defined to analyze the influence of the temporal variability of CO₂eq intensity and electricity price on the environmental impact and economy of the bus. For every individual day of a year, charging periods with the lowest and highest costs and emissions are identified and recommendations for daily bus operation are made. To enable both the ecological and economical operation of the bus, the parameters of electricity price and CO₂ are weighted differently, and several charging periods are proposed, taking into account the priorities previously set. A sensitivity analysis is carried out to evaluate the influence of selected parameters and to derive recommendations for improving the ecological and economic balance of the battery-powered electric vehicle. In all scenarios, the optimization of the charging period results in energy cost savings of a maximum of 13.6% compared to charging at a fixed electricity price. The savings potential of CO₂eq emissions is similar, at 14.9%. From an economic point of view, charging between 2 a.m. and 4 a.m. results in the lowest energy costs on average. The CO₂eq intensity is also low in this period, but midday charging leads to the largest savings in CO₂eq emissions. From a life cycle perspective, the electric bus is not economically competitive with the conventional bus. However, from an ecological point of view, the electric bus saves on average 37.5% CO₂eq emissions over its service life compared to the diesel bus. The reduction potential is maximized if the electric vehicle exclusively consumes electricity from solar and wind power. Y1 - 2020 U6 - https://doi.org/10.1016/j.trd.2020.102293 SN - 1361-9209 VL - 81 IS - Article 102293 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Paulsen, Svea A1 - Hoffstadt, Kevin A1 - Krafft, Simone A1 - Leite, A. A1 - Zang, J. A1 - Fonseca-Zang, W. A1 - Kuperjans, Isabel T1 - Continuous biogas production from sugarcane as sole substrate T2 - Energy Reports N2 - A German–Brazilian research project investigates sugarcane as an energy plant in anaerobic digestion for biogas production. The aim of the project is a continuous, efficient, and stable biogas process with sugarcane as the substrate. Tests are carried out in a fermenter with a volume of 10 l. In order to optimize the space–time load to achieve a stable process, a continuous process in laboratory scale has been devised. The daily feed in quantity and the harvest time of the substrate sugarcane has been varied. Analyses of the digester content were conducted twice per week to monitor the process: The ratio of inorganic carbon content to volatile organic acid content (VFA/TAC), the concentration of short-chain fatty acids, the organic dry matter, the pH value, and the total nitrogen, phosphate, and ammonium concentrations were monitored. In addition, the gas quality (the percentages of CO₂, CH₄, and H₂) and the quantity of the produced gas were analyzed. The investigations have exhibited feasible and economical production of biogas in a continuous process with energy cane as substrate. With a daily feeding rate of 1.68gᵥₛ/l*d the average specific gas formation rate was 0.5 m3/kgᵥₛ. The long-term study demonstrates a surprisingly fast metabolism of short-chain fatty acids. This indicates a stable and less susceptible process compared to other substrates. Y1 - 2020 U6 - https://doi.org/10.1016/j.egyr.2019.08.035 N1 - 6th International Conference on Energy and Environment Research, ICEER 2019, 22–25 July, University of Aveiro, Portugal VL - 6 IS - Supplement 1 SP - 153 EP - 158 PB - Elsevier ER - TY - CHAP A1 - Kern, Alexander A1 - Imani Vashiani, Anahita A1 - Timmermanns, Tobias T1 - Threat for human beings due to touch voltages and body currents caused by direct lightning strikes in case of non-isolated lightning protection systems using natural components T2 - 35th International Conference on Lightning Protection (ICLP) and XVI International Symposium on Lightning Protection (SIPDA) N2 - For typical cases of non-isolated lightning protection systems (LPS) the impulse currents are investigated which may flow through a human body directly touching a structural part of the LPS. Based on a basic LPS model with conventional down-conductors especially the cases of external and internal steel columns and metal façades are considered and compared. Numerical simulations of the line quantities voltages and currents in the time domain are performed with an equivalent circuit of the entire LPS. As a result it can be stated that by increasing the number of conventional down-conductors and external steel columns the threat for a human being can indeed be reduced, but not down to an acceptable limit. In case of internal steel columns used as natural down-conductors the threat can be reduced sufficiently, depending on the low-resistive connection of the steel columns to the lightning equipotential bonding or the earth termination system, resp. If a metal façade is used the threat for human beings touching is usually very low, if the façade is sufficiently interconnected and multiply connected to the lightning equipotential bonding or the earth termination system, resp. KW - Lightning protection system KW - down-conductor KW - steel columns KW - metal façade KW - touch voltage Y1 - 2021 SN - 978-1-6654-2346-5 U6 - https://doi.org/10.1109/ICLPandSIPDA54065.2021.9627465 N1 - 35th International Conference on Lightning Protection (ICLP) and XVI International Symposium on Lightning Protection (SIPDA), 20-26 Sept. 2021, Colombo, Sri Lanka PB - IEEE CY - New York, NY ER -