||Analysis of Hybrid SOFC-Stirling Engine Plants
||Munoz, Carlos Boigues
||Rokni, Masoud (Thermal Energy Systems, Department of Mechanical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Carlsen, Henrik (Thermal Energy Systems, Department of Mechanical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
||Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
||The wish of producing electrical energy with high efficiencies and low contamination levels has been motivation enough to undertake the study of the hybrid SOFC-Stirling engine power plant.
The purpose of the project is to analyse the optimum power plant configuration and type of fuel to obtain 10 electrical kilowatts.
Three fuels have been studied for fuelling the SOFC stacks: Natural Gas, ammonia and methanol. The configuration of the power plant is different for each fuel type, as they require different processes in the plant cycle. The optimization for each configuration has been carried out looking for a compromise between maximum efficiency and low cost.
The calculations have been carried out in DNA (Dynamic Network Analysis), a component-based simulation tool for energy systems, created and developed in the Thermal Energy Systems Department of DTU.
The first attempt of integrating an SOFC plant with a Stirling cycle has been developed, obtaining an improved Natural Gas power plant with an efficiency value of 59,01%, which represents an efficiency increase of 16,46% with respect to the original Natural Gas power plant (50,67%). In both plants the fuel has to be desulphurized and pre-reformed before entering the SOFC stack. For the ammonia power plant, the optimum configuration operating at nominal load has a thermal efficiency of 57,89%, and the fuel does not have to undergo any physicochemical treatment before entering the SOFC, it only needs to increase its temperature to 650ºC. The methanol power plant has an efficiency of 55,12%. The methanol needs to be steam reformed before entering the anode inlet of the SOFC, so the steam present in the used fuel mass flow is used for the purpose. This is accomplished by recirculating part of the used fuel mass flow to the methanol stream.
The thermoeconomic analysis carried out demonstrates that currently none of the power plants analysed can compete with the traditional power generation systems, as the cost of electricity is higher than the market price. In the actual time, the lowest cost of generated electricity corresponds to the ammonia power plant, with 0,2742€/kWh, whilst the market price was 0,2462€/kWh in 2010. For a conservative hypothesized future scenario, were the price of the SOFC stacks and Stirling engine is lower than the actual price, the electricity generated by the ammonia power plant has a cost of 0,1828€/kWh.
||DTU Mechanical Engineering
Creation date: 2012-01-11
Update date: 2012-01-11