Field test with Stirling engine micro-combined heat and power units in residential buildings

The Institute for Energy Economy and Application Technology (IfE), together with the Energie Südbayern (ESB), the local gas supplier in southern Bavaria, are responsible for a field measurement campaign of four gas fired Stirling engine micro-combined heat and power units. These units and the measurement equipment were installed in four different single family houses at the end of 2009. After monitoring over 1 year, it can be said that the Stirling engine micro-combined heat and power units are capable in supplying small residential buildings with thermal and electric power. The data evaluation shows the micro-combined heat and power-units work with a steady-state efficiency above 90%. The main goals of this field test, besides the verification of the Stirling engine’s efficiency, are an analysis of the complete system’s overall energy performance. Therefore, a detailed examination of not only the heat-consuming devices, space heating and the domestic hot water system, but also the examination of heat-generating devices, the Stirling engine and the auxiliary burner were made. The implementation of heat demand curves helps to assess not only the steady state, but also the yearly performances of each micro-combined heat and power units. For a future integration of micro-combined heat and power units into a smart grid, they have to be predictable. Hence, a detailed analysis was taken onto the electricity generation curves at different ambient temperatures and its hourly behaviour. Lastly, for the economic evaluation, the onsite consumption characteristics were considered in depth.