The aim of the project is the development and the successful test of a pellets test furnace with an integrated 5 kW(el) Stirling-engine with an excellent electrical efficiency compared to the employed primary energy. In contrast to add-on solution of Stirling modules in pellet boilers the current project develops a test furnace with a fully integrated Stirling-engine. With a optimal combustion and optional secondary measures for dust reduction and recovery of exhaust heat for pre heating the combustion air, the requirements of a clean and hot flue gas are fulfilled. The disadvantages of high flue gas temperature e.g. thermal stress of the materials, generation of thermal NOx and slag from ash were considered during the development. To eliminate the still consisting dust pollution of the flue gas an additional cleaning system or clean-keeping concept of the heater-heat exchanger will be developed. Further innovations, like reduction of piston friction, optimization of modulation capability and break down management, for increasing the efficiency of the Stirling engine will be realized. The developed combustion concept will be checked with a CFD-model (computational fluid dynamics). With the help of CFD simulation, a test furnace will be designed, built and tested (task of TU Wien partner). The project results could be summarized with the first operational experience and scientific findings of the developed components. Further results are the determination and optimization of the electrical and thermal efficiency of the Stirling-Biomass-System.