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The indirect electrification of the sectors heating, mobility and chemical industry by power-to-X processes may play a significant role in transforming our energy system, because not all processes can easily use electrical power directly. The high-temperature co-electrolysis is particularly well suited to produce synthesis gas as feedstock for various power-to-fuel and power-to-chemicals processes.Besides the energy- and cost-intensive direct air capture, biogenic carbon dioxide emissions are promising candidate for supplying the CO2. Biogas contains between 30 - 50 vol. % of CO2 besides methane and trace impurities and is available in a significant amount in Europe. The biogas can be upgraded by separating the CO2 and methane. However, since the upgrade plants add additional costs and the combination is often not economically viable, biogas is in most cases directly burned in CHP plants.To harness the significant carbon potential of biogas, an oxyfuel combustion may be used, which avoids the dilution of CO2 with nitrogen from the air and emits a mixture of steam and CO2 that could be used directly in a co-electrolysis system for re-usage of CO2. Recent investigations show, that this mixture can be supplied for low costs by retrofitting existing biogas combustion to an oxyfuel combustion. This contribution will investigate the performance and operation of short-stacks containing Ni/YSZ-based solid-oxide cells with simulated flue gases from such a biogas-oxyfuel process.However, biogas also contains trace impurities originating from the biomass, foremost sulfuric species and siloxanes. Before combustion, these are partially removed from the gas, but some traces remain and are converted to oxidized combustion products. In particular, the impact of these oxidized contaminants on the degradation behavior of the cells will be considered and experimentally investigated.

Energies: open-access journal of related scientific research, technology development and studies in policy and management 15(14), 4975 (2022). doi:10.3390/en15144975, Published by MDPI, Basel

Reaction chemistry & engineering (2022). doi:10.1039/D2RE00282E, Published by Royal Society of Chemistry, Cambridge

Synthetic energy carriers that are not based on crude oil or natural gas can contribute to the transcending of fossil-based sources of energy in the future. A contemporary example is the organic substance, oxymethylenether (OMEn), which consists of hydrogen, carbon, and oxygen. It is reported in the literature that OMEn suppresses the formation of harmful NOx and soot and reduces CO2 emissions during the combustion process in internal combustion engines due to its high oxygen content. For the investigation presented in this paper, the use of OMEn was transferred to the autothermal reforming (ATR) process, which is normally conducted using pure diesel fuel or kerosene in order to produce a hydrogen-rich reformate gas to operate fuel cell systems. Different mixtures of OMEn and Ultimate diesel fuel were fed into Jülich's ATR 14 at a steady state. Thereby, approved reaction conditions from former ATR diesel fuel experiments with respect to O2/C and H2O/C molar ratios (0.47 and 1.9, respectively) and temperatures of the educts were applied. It was observed that the addition of OMEn to Ultimate diesel fuel resulted in stable temperatures at characteristic positions within ATR 14 and had a positive effect on the quality of the ATR product gas (reformate). For instance, the concentration of the undesired byproducts ethene and benzene decreased from 800 ppmv to the range of roughly 230 ppmv and from some 130 ppmv to less than 40 ppmv, respectively, when the mass fraction of OMEn in the OMEn/Ultimate diesel mixture was increased from 0% to 30%.

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