Technical, environmental and economic evaluation of a kW-level flared gas-fuel GT-SOFC hybrid system

Recovery of flared gas for electricity production via the use of a hybrid system combining a Solid Oxide Fuel Cell (SOFC) system and gas turbine (GT) technology was explored as a promising non-flaring method. The proposed hybrid system offers an innovative solution to significantly reduce atmospheric emissions and avoid energy loss caused by flaring. Indeed, a comprehensive numerical model of the process is developed, integrating mass and energy balance modeling via ASPEN PLUS software, coupled with an electrochemical model using MATLAB software. The effects of three internal reforming scenarios taking place at the SOFC anode including partial oxidation (PO), steam reforming (SR) and dry reforming (DR) were evaluated. Simulation results at SOFC celllevel showed that the internal steam reforming scenario was the best scenario occurring in-situ the anode side and ensuring a higher H2 concentration in the reformate gas. This scenario was used as a basic operating mode for subsequent simulations at the stack-level. Furthermore, the scaled-up SOFC kW-level was integrated with GT technology and showed a maximum power density of about 3 kW.m-2 for a stack area of 191.2 m2, giving a total system output power of 1.238 MW. Under the design conditions, economic and environmental evaluation showed an Electricity Production Cost (EPC) of about 0.08 $/kWh and a daily carbon dioxide emission of about 13 eq. tCO2/day equivalent to 0.2092 eq. kgCO2/kWh. Finally, a sensitive study highlighting the impact of the inlet flared gas flow rate on various economic parameters was performed.