Energy analysis of a novel domestic scale integrated wooden pellet-fueled micro-cogeneration concept

•Energy analysis for three concepts of pellet-fueled micro-cogeneration is presented.•Building performance is assessed for two energy performance levels in three climates.•Both electrical and thermal demands can be fulfilled with a good energy match.•The energy match can be improved by adding an electrical or a thermal storage.

In this paper, the feasibility of conceptual 1.9 kWe micro-cogeneration technologies is evaluated by way of annual energy balances and weighted energy matching indices (WMI). The concept is based on a commercial 20 kWth wooden-pellet fueled boiler, in which a rotary steam engine (RSE), a Stirling engine (SE) or a domestic thermoelectric cogeneration system (DTCS) can be easily integrated. Both thermal and electrical tracking strategies are examined with an option to charge an electric car and to deliver surplus heat to a local thermal grid. The sizing of electrical and thermal storages is discussed. The hourly energy demands are simulated using the whole-building simulation tool IDA-ICE for detached houses representing two energy performance levels and located in three climatic zones in Finland. The performance of micro-cogeneration is assessed through electrical and thermal efficiencies obtained from recently published performance analyses. The results indicate that by using the suggested concept, the energy demands of the case building can be met in cold climates and a good energy match can be obtained. The energy match can be improved slightly by using an electrical storage of maximum 100 A h (4.8 kW h) or a thermal storage of maximum 1500 L (17.5 kW h).