The Demosofc Project: Preliminary Results from an Industrial-Size Biogas-Fed Solid Oxide Fuel Cell

Abstract

The EU-funded DEMOSOFC project (www.demosofc.eu) aims to demonstrate the technical and economic feasibility of operating a 174 kWe SOFC in a wastewater treatment plant (WWTP). The fuel for the three SOFC modules (3x58 kWe) is biogas, which is available on-site from the anaerobic digestion of sludge collected from the treated wastewater. A heat-recovery loop allows to recover useful thermal energy from the hot SOFC exhaust gases (90-100 kWth). The recovered heat is transferred through a water loop to the sludge, which is pre-heated to 40-45 °C before feeding the digester. A full thermal recovery within the WWPT is thus achieved. Energy generated and recovered from the SOFCs will be consumed at the WWTP and will cover about 30% of the overall electricity demand and 50% of the yearly thermal demand.The WWTP is located in Collegno, in the Turin premises (IT). The Collegno plant is serving around 180’000 Person Equivalent (P.E.), both residential and industrial users, and currently, exploits biogas for heating-only in a boiler. The integrated biogas-SOFC plant includes three main units: 1) the biogas clean-up and compression section; 2) the three SOFC power modules, and 3) the heat recovery loop. The scope of the project is demonstrating the high-efficiency conversion of renewable fuel into electricity and heat. The three SOFC modules are supplied by Convion (www.convion.fi), partner of the DEMOSOFC project. The first module has been shipped to Turin during April 2017, and the demonstration phase will last four years (2017-2020). The expected net electric efficiency of the SOFC is in the range 52-55%. A special focus of the demonstration is the deep and reliable removal of harmful contaminants for the SOFC (mostly H2S and siloxanes) that are found in the raw biogas. In-line and real-time gas analysis are installed to monitor the removal efficiency of the biogas clean-up unit, which relies on solid sorbents (e.g., activated carbons).The present work is related to the first on-field test of the SOFC units and the starting of the entire plant. After having completed mechanical and electrical connections, the first module has been fed by clean and compressed biogas on site produced and activated with a dedicated start-up procedure. The analysis is related to the SOFC operation, with a description of the starting procedure and preliminary performance results. The on-site produced and measured AC electric power is employed for the calculation of the net electrical efficiency; dedicated emissions measurements have been performed with simulated biogas at Convion facilities and will be replied on-site during the system operation. Figure 1