Economic Feasibility of Power/Heat Cogeneration by Biogas–Solid Oxide Fuel Cell (SOFC) Integrated Systems

Based upon the thermodynamic simulation of a biogas-SOFC integrated process and costing its elements, present work examines economic feasibility biogas-SOFCs for combined heat power (CHP) generation, by comparison their performance against conventional biogas-CHP with internal combustion engines (ICEs), under same assumptions. As well as issues scale an SOFC’s cost, examined in literature, study brings up determinative effects of: (i) employed SOFC size, respect to operational point, (ii) criterion, on assessment. Two plant capacities were (250 m3·h−1 750 biogas production), feasibilities assessed Internal Rate Return (IRR), Net Present Value (NPV) Pay Back Time (PBT) criteria. For costs at 1100 2000 EUR·kWel−1, foreseen 2035 2030, respectively, SOFCs found increase investment (by 2.5–4.5 times, depending plant’s capacity size) generation 13–57%, size), latter increasing revenues. SOFC-CHP exhibits considerably lower IRRs (5.3–13.4% small 16.8–25.3% larger plant), compared ICE-CHP (34.4%). Nonetheless, according NPV that does not evaluate profitability return investment, (NPVmax: EUR 3.07 M) can compete biogas-ICE (NPV: 3.42 M), sized operate 70% maximum density (MPD) cost whereas plants, lead higher NPVs (EUR 12.5–21.0 9.3 M). PBTs are (7.7–11.1 yr 4.2–5.7 large plant, 2.3 3.1 biogas-ICE) because criterion suppresses effect SOFC-CHP-increased revenues time period shorter than lifetime. Finally, economics optimized 70–82.5% MPD, criterion. Overall, choice size drastically affect evaluation SOFC-CHP, also determines economically optimum SOFC.