@article{KaulBoellmannThemaetal., author = {Kaul, Anja and Boellmann, Andrea and Thema, Martin and Kalb, Larissa and Stoeckl, Richard and Huber, Harald and Sterner, Michael and Bellack, Annett}, title = {Combining a robust thermophilic methanogen and packing material with high liquid hold-up to optimize biological methanation in trickle-bed reactors}, series = {Bioresource technology}, volume = {345}, journal = {Bioresource technology}, publisher = {Elsevier}, doi = {10.1016/j.biortech.2021.126524}, abstract = {The hydrogen gas-to-liquid mass transfer is the limiting factor in biological methanation. In trickle-bed reactors, mass transfer can be increased by high flow velocities in the liquid phase, by adding a packing material with high liquid hold-up or by using methanogenic archaea with a high methane productivity. This study developed a polyphasic approach to address all methods at once. Various methanogenic strains and packings were investigated from a microbial and hydrodynamic perspective. Analyzing the ability to produce high-quality methane and to form biofilms, pure cultures of Methanothermobacter performed better than those of the genus Methanothermococcus. Liquid and static hold-up of a packing material and its capability to facilitate attachment was not attributable to a single property. Consequently, it is recommended to carefully match organism and packing for optimized performance of trickle-bed reactors. The ideal combination for the ORBIT system was identified as Methanothermobacter thermoautotrophicus IM5 and DuraTop (R).}, language = {en} } @article{ThemaWeidlichKauletal., author = {Thema, Martin and Weidlich, Tobias and Kaul, Anja and B{\"o}llmann, Andrea and Huber, Harald and Bellack, Annett and Karl, J{\"u}rgen and Sterner, Michael}, title = {Optimized biological CO2-methanation with a pure culture of thermophilic methanogenic archaea in a trickle-bed reactor}, series = {Bioresource Technology}, journal = {Bioresource Technology}, number = {333}, publisher = {Elsevier}, doi = {10.1016/j.biortech.2021.125135}, abstract = {In this study, a fully automated process converting hydrogen and carbon dioxide to methane in a high temperature trickle-bed reactor was developed from lab scale to field test level. The reactor design and system performance was optimized to yield high methane content in the product gas for direct feed-in to the gas grid. The reaction was catalyzed by a pure culture of Methanothermobacter thermoautotrophicus IM5, which formed a biofilm on ceramic packing elements. During 600 h in continuous and semi-continuous operation in countercurrent flow, the 0.05 m3 reactor produced up to 95.3 \% of methane at a methane production rate of 0.35 mCH43mR-3h-1. Adding nitrogen as carrier gas during startup, foam control and dosing of ammonium and sodium sulfide as nitrogen and sulfur source were important factors for process automation.}, language = {en} } @article{HeberlWithelmKauletal., author = {Heberl, Michael and Withelm, Christian and Kaul, Anja and Rank, Daniel and Sterner, Michael}, title = {Prospective Life Cycle Assessment of Biological Methanation in a Trickle-Bed Pilot Plant and a Potential Scale-Up}, series = {Energies}, volume = {17}, journal = {Energies}, number = {9}, publisher = {MDPI AG}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en17092206}, abstract = {The fluctuating nature of renewable energies results in the need for sustainable storage technologies to defossilize the energy system without other negative consequences for humans and the environment. In this study, a pilot-scale trickle-bed reactor for biological methanation and various scale-up scenarios for 2024 and 2050 were investigated using life cycle assessment. A best- and worst-case scenario for technology development until 2050 was evolved using cross-consistency analysis and a morphological field, based on which the data for the ecological models were determined. The results show that the plant scale-up has a very positive effect on the ecological consequences of methanation. In the best-case scenario, the values are a factor of 23-780 lower than those of the actual plant today. A hot-spot analysis showed that electrolysis operation has an especially large impact on total emissions. The final Monte Carlo simulation shows that the technology is likely to achieve a low global warming potential with a median of 104.0 kg CO2-eq/MWh CH4 and thus can contribute to decarbonization.}, language = {en} }