Exergoenvironmental analysis for a geothermal district heating system: An application

• Using exergoenvironmental analysis in a geothermal district heating for the first time.
• Evaluating environmental impact of a geothermal district heating system.
• Discussing the effects of ambient and wellhead temperatures on the environmental impact.
• Total environmental impact of the system occurs from exergy destructions of components.
• The exergoenvironmental analysis can be done only once for all the ambient temperatures.

Energy sources are of great importance in relation to pollution of the world. The use of renewable energy resources and the creation of more efficient energy systems make great contributions to the prevention of greenhouse gases. Recently, many studies indicate that the energy conversion systems have many advantages in terms of technical and economic point of view. In near future, environmental impact is going to play an important role in the selection/design of such energy resources and systems. In this study, the Afyon GDHS (geothermal district heating system) having actual operating conditions is investigated at the component level in terms of environmental impact by using exergoenvironmental analysis. Moreover, the effects of ambient and wellhead temperatures on the environmental impacts of the system are discussed. The results show that a great part of total environmental impact of the system occurs from the exergy destructions of the components. Therefore, the environmental impacts can be reduced by improving their exergetic efficiencies instead of design changes of the system components. The environmental impacts of the system are reduced when the ambient temperature decreases and the wellhead temperature increases. Thus, it might not be necessary to conduct separately the exergoenvironmental analysis for different ambient temperatures.