Numerical analysis of operating range and SOFC-off-gas combustor requirements of a biogas powered SOFC-MGT hybrid power plant

Abstract

Hybrid Power plants (HyPP) combining a micro gas turbine with a solid oxide fuel cell are projected to reach very high electric efficiency values. Powered by biogas, they have the potential to become an important pillar for a future CO 2-neutral energy mix. However, to compensate the fluctuating energy yield of wind turbines and photovoltaic power plants they should also provide a wide operating range. While previous numerical studies show that this is the case for natural gas powered HyPP, the impact of biogas utilization on the operating range was still unknown. In the present study, a detailed numeric model of the HyPP being constructed at DLR is presented. The model is used for an in-depth investigation of the operating limits using biogases with various methane contents. The influence of fuel cell operating limits, like the stack temperature, minimal cell voltage and maximal fuel utilization rate, on the HyPP operation range are discussed. While the results show a strong correlation between methane content and operation range, a power output reduction of 33 % is still feasible for methane contents as low as 60 vol%. Knowing the operating range of the HyPP is also crucial for the design of the plants components. Hence, in a final step the operating conditions for the fuel cell off-gas combustor are derived for the respective operating ranges.

Numerical Modeling of Energy Systems Based on Micro Gas Turbine: A Review

“…The four parameters considered were air-steam mixtures as reforming agents, fuel utilization factor, turbine inlet temperature, and compression ratio, and the several sets of information resulting from the analysis represent valuable knowledge for direct-biogas SOFC operational performance. Krummrein et al [74] investigated the performance related to the use of biogas fuel for their hybrid power plant SOFC-MGT demonstrator. Results of steady state simulations showed that the thermodynamic parameters are only slightly influenced by the substitution of methane with biogas.…”

“…In Table 5, a summary of the literature reviewed in this subsection has been listed. Performance maps [74] Turbec T100 ChemCAD TIT variability with SOFC (Subroutines for SOFC and gasifier?) [75] Turbec T100 Aspen Plus [76] 4.3.…”

Techno-Economic Assessment of CHP Systems in Wastewater Treatment Plants

“…Pressurizing the gases in the compressor prior to entering the SOFC raises the electrical efficiency of the SOFC [81]. This approach can be a high electrical efficiency option, especially for small-scale CHP [82]. Use of these combined systems is also being explored for auxiliary power units in the transportation sector [83].…”

Modeling Analysis of SOFC System Oriented to Working Condition Identification

“…Antonucci investigated the acceptable cost of sodium chloride nickel cell hybrid system using SOFC [15]. Krummrein proposed a detailed numerical model of hybrid system (SOFC + micro turbine), and discussed the influence of fuel cell operation limit on the operation range of hybrid power station, including stack temperature, minimum stack voltage, and maximum fuel utilization [16]. Lee used a simplified two-dimensional axisymmetric model domain to simulate the performance of a 1 kW fuel cell reforming unit.…”