Environmental assessment of a binary geothermal sourced power plant accompanied by exergy analysis

Abstract

In this study, a geothermal power plant endowed with actual operational conditions and its equipment are evaluated using exergoenvironmental analysis from the perspective of environmental impact. Environmental impacts related to equipment (including construction, operation/maintenance and disposal), exergy destruction and pollution formation are taken into consideration. Moreover, effects of ambient temperature and brine input temperature with respect to environmental impact factors of the system are also discussed. Though this analysis, relative difference of specific environmental impacts, exergoenvironmental factor and total environmental impact are determined as 122% and 2.5% and 2285 Pts/h, respectively. The results of the study show that 98% of total environmental impact for the geothermal power plant is the cause of exergy destruction of the equipment involved. For this reason, improvement of exergetic efficiency for equipment should be considered rather than construction, operation/maintenance and disposal changes of system equipment. Hence, it is probably possible to have a higher capacity plant by getting a better condenser performance, as well as strengthening the vaporizers and the pumps. Besides, approximately 44 Pts/h of non-condensable gas-NCG (CO2 mostly) released from vaporizer to atmosphere caused environmental impact of the system to be measured as high environmental impact value of electricity equal to 0.108 Pts/kWh. In conclusion, conditions during which the ambient temperature decreases and brine input temperature increases, the system’s environmental impacts concurrently decrease. This study is expected to serve as a guidework for researchers involved in environmental impacts of geothermal power plants and improvement of the plants in terms of environmental impact.