Economic and environmental analysis of replacement of natural gas heating system with geothermal heat pump in district 11 of Tehran

Considering the fact that fossil fuels resources with their extreme environmental contaminants are coming to an end, clean and renewable energy utilization is taken into account. One of the simplest renewable energy resources which can also be used for heating and cooling is ground source heat pump (GSHP). Not only natural gas utilization is very costly because of subsidies for Iranian government, but also imposes massive amount of air pollution into the atmosphere and causes external costs as well. In this paper, by modeling the buildings which are having construction permission in district 11 of Tehran city by 2014, the exchange of GSHP’s with common systems by government support is studied. The results showed that by using GSHP in each year, more than 100’568 tons of air pollutant is prevented to be spread and the amount of reduced environmental costs due to contaminant is estimated to be 641’364 $. Besides, 12’931’360 cubic meters of natural gas can be saved annually. Regarding to gas exportation price in 2014, 3’232’840 $ profit will be gained from gas exportation. After all, Iranian government strategies to encourage households in order to apply this system are discussed. It is found with government supports for using GSHP’s, the rate of return will be changed from 18 years (with no governmental support) to less than 2 years.