Analysis of Innovative Micro-CHP Systems to Meet Household Energy Demands

This paper presents an analysis aimed to evaluate the feasibility of micro-CHP systems to meet household energy demands of a single family user. The considered CHP systems are based on innovative technologies, which are already available on the market or will be available in the short-term period, and that have an electric power output suitable for a single family user, i.e. the electric power must be close to a few kW. The considered technologies (micro gas turbines, micro Rankine cycles, Stirling engines and thermophotovoltaic generators) are compared to the internal combustion engine, which is currently the only well-established technology for small size CHP. For two single-family dwellings, characterized by different floor areas and shape factors, a specific certification of energy performance was carried out, to estimate yearly energy requirements. Daily profiles of electric, thermal and cooling loads are instead estimated by using literature data. Five CHP systems are considered, which are composed of (i) a prime mover (internal combustion engine, micro gas turbine, micro Rankine cycle, Stirling engine or thermophotovoltaic generator), (ii) a thermal energy storage unit and (iii) an auxiliary boiler used to cover peak thermal demands which cannot be met by both the CHP unit and the thermal energy storage unit. The energy performance, in terms of primary energy saving, and the maximum cost allowed for each CHP system are evaluated, to identify the most suitable technology, prime mover and thermal energy storage unit size. For this purpose, the influence of specific tariff conditions in the present market scenario is evaluated thoroughly.