Solid oxide fuel cell micro combined heat and power system operating strategy: Options for provision of residential space and water heating

Solid oxide fuel cell (SOFC) based micro combined heat and power (micro-CHP) systems exhibit fundamentally different characteristics from other common micro-CHP technologies. Of particular relevance to this article is that they have a low heat-to-power ratio and may benefit from avoidance of thermal cycling. Existing patterns of residential heat demand in the UK, often characterised by morning and evening heating periods, do not necessarily complement the characteristics of SOFC based micro-CHP in an economic and technical sense because of difficulties in responding to large rapid heat demands (low heat-to-power ratio) and preference for continuous operation (avoidance of thermal cycling). In order to investigate modes of heat delivery that complement SOFC based micro-CHP a number of different heat demand profiles for a typical UK residential dwelling are considered along with a detailed model of SOFC based micro-CHP technical characteristics. Economic and environmental outcomes are modelled for each heat demand profile. A thermal energy store is then added to the analysis and comment is made on changes in economic and environmental parameters, and on the constraints of this option. We find that SOFC-based micro-CHP is best suited to slow space heating demands, where the heating system is on constantly during virtually all of the winter period. Thermal energy storage is less useful where heat demands are slow, but is better suited to cases where decoupling of heat demand and heat supply can result in efficiencies.