Status of geothermal energy in world and Turkey and studies in ITU

After roughly 100 years of the first electricity generation, installed capacity of geothermal power plants have grown to 8900 MW in 25 countries, producing 56830 GWh/year. An estimate of the installed thermal power in the world for direct utilization at the end of 2004 is 27825 MWt. Thermal energy used is 261418 TJ/yr. The distribution of thermal energy used by category is approximately 33% for geothermal heat pumps, 29% for bathing and swimming, 20% for space heating (of which 77% for district heating), 7.5% for greenhouse heating and open ground heating, 4% for industrial process heat, 4% for aquaculture and 2% for others uses. A conventional steam cycle power plant with 17.8 MWe capacity was installed in Kizildere geothermal field and has been generating an average gross power of 10 MWe since 1984. An air cooled binary cycle power plant with gross capacity of 8.5 MWe is being built in Aydin-Salavatli has been in operation for two months. A decision was made to install another power plant with a capacity of 45 MWe in Aydin-Germencik that reservoir assessment studies are being conducted Direct utilization of geothermal resources in Turkey are about 500 MWt of which 250 MWt is used by district heating,140 MWt utilized by greenhouse heating and 100 MWt belong to bathing Turkeys geothermal potential as geothermal resource base was estimated as 3.1x1023 J. Later information on the geothermal potential was provided by Serpen and Turkeys geothermal resource base was found 2.85x1023 J. Recent studies by Serpen revealed Turkeys convertible energy from geothermal resources in 3 categories as 1.2E22 J for direct use (in two categories) and 1.3E18 J for indirect use. Stochastic studies conducted on economics of geothermal resources in Turkey by Serpen revealed that power generation looks profitable with the electricity selling prices of around 4.5-5 cents/kWh. The payout time for this type of investments reaches 7 to 8 years. District heating systems do not seem to be profitable with actual low fixed rate heat payments (tariffs). On the other hand, greenhouse heating, other type of direct-use, looks very profitable. Health Spa investments looks promising and feasible. It is unfortunate that Turkey, having rich geothermal resources, many utilization opportunities and know-how, has not been able to run her geothermal potential due to lack of a proper geothermal law. There are several draft codes for geothermal energy in circulation; one prepared by Ministry of Energy, another by Ministry of Interior. Neither of drafts could meet Turkeys needs for geothermal energy in a contemporary way. The following results are obtained by this study: Geothermal resources of the world could provide 8% of the power generation needs of the world in the near future. Increasing oil prices would enable to improve the economics of developing enhanced geothermal resources in the future and would eventually double power generation from geothermal resources. Utilization of low grade geothermal resources should replace fossil fuels locally for direct-use in the world and Turkey. Utilization of geothermal resources instead of fossil fuels will eventually reduce social costs by controlling CO2 levels. In Turkey, economics of power generation looks sound, and new projects are in line. Economics of district heating systems with existing financial model and tariffs in Turkey are not in good shape, and they will not be able to compete with natural gas in the short and mid term. Turkey has suitable geothermal resources for the utilization of process heating, and this should be emphasized and taken into account by industrialists. The utilization of geothermal resources of Turkey in greenhouse heating seems economically sound, and industry has already sensed that trend. Taking into account of Turkeys rich geothermal resources she merits a contemporary geothermal legislation, but the existing official drafts of geothermal law are insufficient and far from to meet actual requirements of Turkey in many aspects.