SOFC Operation with Real Biogas

Abstract

Biogas is a valuable energy source and will be available in future in systems relying on renewables. It is an attractive fuel for solid oxide fuel cells (SOFC), which are able to utilize the carbon contained in the biogas and which produce electricity with high efficiency. In the current paper, state‐of‐the‐art SOFCs were studied regarding performance and durability in relation to biogas as fuel and considering important contaminants, specifically sulfur. First, the catalytic behavior in relevant synthetic biogas mixtures was studied and the potential of dry reforming was demonstrated. Successful long term operation of an SOFC under both, conditions of steam and dry reforming, i.e., addition of steam or CO2 to avoid carbon formation was shown. For the steam reforming case a remarkable period of 3,500 h, hereof 3,000 h in the presence of H2S was achieved. Finally, a real biogas from a landfill gas unit was used as fuel. The concept of dry reforming was realized. The SOFC was successfully operated with and in one case even without a specific gas cleaning unit.

Operation of solid oxide fuel cells with alternative hydrogen carriers

“…This finding was confirmed at SOFC cell level in the presence of sulphur impurities and typical biogas compositions [35]. The observed degradation of the power output under steam reforming conditions was even stopped when using CO2 as reforming agent instead of steam [15].…”

“…Catalytic studies on SoA anodes indicated that the presence of CO2 can mitigate the sulphur poisoning effect on the methane reforming reaction [34]. This finding was confirmed at SOFC cell level in the presence of sulphur impurities and typical biogas compositions [35]. The observed degradation of the power output under steam reforming conditions was even stopped when using CO2 as reforming agent instead of steam [15].…”

“…State-of-the-art (SoA) SOFC anodes are composed of a composite between nickel and yttria stabilized zirconia (Ni/YSZ cermet), nickel being a catalyst, which cansimilar to large-scale catalytic reforming processes [9,10] -reform hydrocarbons with steam or CO2 within the SOFC anode [11,12]. This functionality can also be utilized when using biogas [13,14,15,16] as an available fuel in a fossil-free energy scenario. The catalytic activity of the SOFC anode is not restricted to the reforming of hydrocarbons.…”

Effects of Sn doping on the manufacturing, performance and carbon deposition of Ni/ScSZ cells in solid oxide fuel cells

“…Pairing this abundant and under-utilized fuel with SOFC with higher efficiency would increase the generated electricity while considerably reducing the carbon footprint of energy services. In addition, studies by Johnson et al [35] and Hagen et al [36] show that the presence of CO2 (instead of pure methane) in biogas can suppress the effect of sulphur poisoning.…”

Progress of SOFC/SOEC Development at DTU Energy: From Materials to Systems

“…Power output during single cell SOFC test with real biogas from a landfill unit (bottle 1-3 with gas cleaning, bottle 4 without gas cleaning) and an intermediate period using synthetically mixed biogas under dry reforming conditions at 750 o C, from ref (15). …”