This study is particularly aimed at investigating the influence of hydrogen chloride traces in biogas on direct internal reforming in solid oxide fuel cells (SOFCs). The experiments are performed with simulated biogas containing methane to carbon dioxide ratio of 3:2, the usual average proportion in biogas. To the best of our knowledge, there are no reported studies that investigated the effect of hydrogen chloride on direct internal reforming by clearly establishing the effect of reforming with outlet gas composition measurements. The experiments at SOFC operating temperature of 850 °C reveals no negative effect on reforming or cell performance, with 4, 8, and 12 ppm(v) of hydrogen chloride in biogas. At 800 °C, there is no visible performance degradation, but a negligible amount of methane (∼ 1%) is detected in the anode off gas. Both the reforming and electrochemical performance are marginally affected at 750 °C. Further, post-test analyses (FESEM-EDS, XRD) of the used SOFC reveals no damage to the cell at microstructure level or chlorine poisoning. All the experiments are performed in the context of utilizing the biogas generated from sewage treatment plants in an SOFC system. The reported level of chlorine traces in biogas generated from sewage sludge is < 10 ppm(v) and hence the limit set for experiments is at par with this value.@en

Small-scale electrical power generation (<100 kW) from biogas plants to provide off-grid electricity is of growing interest. Currently, gas engines are used to meet this demand. Alternatively, more efficient small-scale solid oxide fuel cells (SOFCs) can be used to enhance electricity generation from small-scale biogas plants. Most electricity generators require a constant gas supply and high gas quality in terms of absence of impurities like H 2S. Therefore, to efficiently use the biogas from existing decentralized anaerobic digesters for electricity production, higher quality and stable biogas flow must be guaranteed. The installation of a biogas upgrading and buffer system could be considered; however, the cost implication could be high at a small scale as compared to locally available alterna-tives such as co-digestion and improved digester operation. Therefore, this study initially describes relevant literature related to feedstock pre-treatment, co-digestion and user operational practices of small-scale digesters, which theoretically could lead to major improvements of anaerobic digestion process efficiency. The theoretical preamble is then coupled to the results of a field study, which demonstrated that many locally available resources and user practices constitute frugal innovations with potential to improve biogas quality and digester performance in off-grid settings. @en

Biomass is predominantly the major source of energy in the global south. It is the readily available source of energy in global south and is used in rural energy households in the form of wood, charcoal and agricultural residues. However, biomass energy source is not utilised in the most efficient way and hence there is still a gap in achieving the SDG 7 target. The growing global population has increased the global demand of energy and other basic resources like water and food. But also, has resulted in increased need of sanitation services which are not readily provided to rural communities.....@en

Internal dry reforming of methane is envisaged as a possibility to reduce on capital and operation costs of biogas fuelled solid oxide fuel cells (SOFCs) system by using the CO2 present in the biogas. Due to envisaged internal dry reforming, the requirement for biogas upgrading becomes obsolete, thereby simplifying the system complexity and increasing its technology readiness level. However, impurities prevailing in biogas such as H2S have been reported in literature as one of the parameters which affect the internal reforming process in SOFCs. This research has been carried out to investigate the effects of H2S on internal dry reforming of methane on nickel-scandia-stabilised zirconia (Ni-ScSZ) electrolyte supported SOFCs. Results showed that at 800°C and a CH4:CO2 ratio of 2:3, H2S at concentrations as low as 0.125 ppm affects both the catalytic and electric performance of a SOFC. At 0.125 ppm H2S concentration, the CH4 reforming process is affected and it is reduced from over 95% to below 10% in 10 h. Therefore, future biogas SOFC cost reduction seems to become a trade-off between biogas upgrading for CO2 removal and biogas cleaning of impurities to facilitate efficient internal dry reforming.@en

Biogas is known as a traditional energy source for off-grid population throughout the world. And currently small-scale solid oxide fuel cell (SOFC) systems are being promoted for off-grid energy supply. Also, electricity demand is increasing at a high rate due to the ever-increasing population and technological revolution. Therefore, promotion of off-grid energy supply needs to be refocused. The small scale biogas-SOFC is an envisaged modern energy system which can meet both the thermal and electrical energy demand for off-grid population more efficiently (60% at 800 °C) than currently available technologies. However, it has been observed that cleaning of biogas could increase the system capital cost by 6–7% and >40% of the overall annual system operating cost. Cost-effective gas cleaning is therefore important for economic feasibility of the biogas-SOFC energy system. This review focuses on technical and economic challenges of current commercial and laboratory scale biogas cleaning technologies. Special focus is directed towards cost mitigation strategies for gas cleaning such as combined in-situ bioreactor upgrading and application of cost-effective sorbents. The results are useful to advance implementation of biogas-SOFC systems in off-grid applications in developing as well as developed world.@en