Modelling the behaviour of domestic micro-cogeneration under different operating regimes and with variable thermal buffering

In the UK large scale field trials (Carbon Trust, 2007) are underway to assess the performance of combustion based, domestic cogeneration devices with regards to both their carbon-saving potential and also their possible impact on the electricity distribution system. The preliminary results indicate that only modest carbon savings are achievable from these devices. However, in these trials the systems tested did not include any thermal buffering between the device and the heating system; hence the results give an incomplete picture of domestic cogeneration performance. This paper describes the preliminary outcomes from a comprehensive modelling exercise that explored the performance of domestic cogeneration for different UK housing types under different operational scenarios, and with and without thermal buffering. The simulation results indicate that thermal buffering has a dramatic effect on the performance and operational characteristics of micro-cogeneration devices however, due to standing losses in the thermal buffering, carbon emissions levels show only small variations. The results from these simulations are contrasted with the evidence emerging from the field trials and it is concluded that the model gives a realistic picture of performance.