Possibilities of increasing the overall efficiency of a Solar dish Stirling system Anna Pääkkönen, Henrik Tolvanen, Jukka Konttinen, Department of Chemistry and Bioengineering, Tampere University of Technology The aim of this work was to investigate the possibilities of increasing a solar/gas-Stirling-engine system overall efficiency. The available fuel for the current installation is either biogas or methane. We suggest adding an external gas engine to the existing system. The engine would run on the same fuel as the Stirling engine and the thermal energy of the exhaust gases would be utilized in the Stirling engine. The results show that adding the reciprocal gas engine can save fuel costs of the system. The external engine also increases the system power production reliability in case of Stirling engine maintenance or breakdown.