Geothermal power projects in Turkey are outliers for this technology because of their very high CO2 emissions rates (800-1600 g/kW-hr) which are comparable to or significantly exceed those from coal-fired power generation (940-980 g/kW-hr). A “typical” 50 MW geothermal project in Turkey producing 1000 g/kW-hr CO2 emits 1,200 tonnes per day of CO2 to the atmosphere. CO2 is discharged to the atmosphere from all geothermal plant types installed to date in Turkey: flash, binary and hybrid flash-binary projects. Turkey lacks pumped binary projects which feature zero CO2 emissions due to use of downhole pumps installed in wells which deliver pressurized liquid to the binary plant. Produced gas is kept in solution in the pumped, pressurized liquid which is reinjected to the reservoir after exiting the heat exchangers, yielding a closed-loop system. Pumping of production wells is generally not feasible in Turkey due to a combination of: 1) high gas contents which can depress the flash point in wells down to depths below the technical limit of downhole pumps; and 2) reservoir temperatures exceeding the 190ºC temperature limitation of the pumps. Declines in CO2 emissions rates over time are possible for some geothermal projects in Turkey due to dilution of reservoir gas by “de-gassed” injectate. However, available data from the Kizildere I and Germencik projects indicates that gas levels still remain very high for one or more decades of plant operation despite declines from initial gas levels at plant start-up. Mitigation of produced CO2 by re-injection to the reservoir is unlikely to be a viable option for Turkey geothermal projects, as there is as yet no precedent for successful sustained re-injection of the massive amounts of CO2 such as produced by these fields. A short-lived experiment at the Coso field in the USA was abandoned due to recycling of injected gas back to production wells, and the scale of ongoing gas injection operations at Hellisheidi in Iceland is too small to be applicable to Turkey projects. A portion of the CO2 produced by the initial plants installed at the Kizildere and Salavatli fields has been sold for commercial uses. However, this represents a small proportion of the total CO2 production by geothermal projects in Turkey and the in-country market for CO2 appears to be saturated. Geothermal projects in Turkey are not environmentally friendly due to the adverse climate impacts of these extreme CO2 emissions rates. Multi-lateral lending agencies such as the European Bank for Reconstruction and Development and World Bank Group are actively providing funding for geothermal development in Turkey, and fueling the recent explosive growth of geothermal capacity in the country. Such financial support is inconsistent with the stated missions of these agencies to reduce greenhouse gas emissions and promote environmentally sustainable projects. Instead, financial support for geothermal development in Turkey should be directed towards facilitating: 1) exploration for and development of other low-gas geothermal systems similar to those already identified at Tuzla and Buharkent; 2) research and development directed towards increasing the pressure and depth limits for downhole pumps so that more gassy geothermal systems in Turkey can be developed as zero-emissions pumped binary projects; and 3) research and development focused on scaling-up of gas reinjection systems such as in operation at Hellisheidi.

Press the Back button in your browser, or search again.

Copyright 2017, Stanford Geothermal Program: Readers who download papers from this site should honor the copyright of the original authors and may not copy or distribute the work further without the permission of the original publisher.