Energy, exergy and environment analyses of a hybrid PV-system district heating system for a new household settlement in Germany

This work presents an exergetic and environmental assessment of a hybrid district heating system (HDHS) and normal district heating system (NDHS) analysed within two supply temperature levels. Energetic, exergetic and environmental performances are investigated. Results indicate that different scenarios have a lower degree of exergy efficiency in comparison to energy efficiency. The HDHS has a higher exergy efficiency (around 2%) and lower primary exergy demand (around 3%) compared to NDHS. Moreover, the combination of photovoltaic (PV) modules and low supply temperature reduces around 90% of the exergy losses. Results of the environmental study confirm that the lower supply temperature added to the PV modules reduce CO2 emissions. In general, exergy analyses of the district heating systems should be conducted to make the exergo-environmental model, the matching of the quality level of demand and supply and the environmental impact, more known to the public and decision makers in the context of multi-grid energy systems.