Numerical and experimental assessment of a novel SOFC-based system for micro-power generation

In this work, a novel micro-scale system based on solid oxide fuel cells (SOFCs) is studied for operation at low temperature, assessing the expected performance numerically and the actual cell operation experimentally. The potential application is powering gas-connected but off-electric-grid remote electronic devices with nominal capacity of tens of watts, such as those necessary to monitor and operate the gas grid, using methane as feed. Since water is generally not available in such distributed uses, feed pre-treating is critical and poses technical challenges for the high and stable performance of the SOFC. Several promising design configurations for the system are defined. The use of commercial YSZ-based SOFCs is envisioned, and recirculation is needed to avoid carbon deposition, which is predicted by the calculation of carbon activity and confirmed by the experimental observations. A higher anodic recirculation is required at low (≤50%) fuel utilization in order to decrease the estimated carbon activity, due to a lower content of oxygen atoms in the anode outlet stream. The anode inlet composition was numerically estimated assuming a fuel utilization factor of 70% with 60% anodic recirculation, then was experimentally tested, achieving a stable power generation without carbon deposition.