[en] As most of the alternative power sources, geothermal energy started being considered as a tentative one during the early 1970s. At that time the world's demand for energy was mostly fed by means of petroleum, coal, gas and other primary materials. The low prices of these raw materials at that time and the lack of general consciousness on the environmental contamination problems caused by the combustion processes did not forecast any significant changes for the coming years. However, as from 1973, a constant raise in prices, specially for liquid fuels, started to take place. A few years later, in the early 1980s, a growing interest for nature and for the delicate equilibrium of the ecological and for systems started to awaken. These facts led several countries to re-evaluate their power resources and to reconsider those showing less negative incidence upon the environment. Among such alternatives, geothermal energy introduces certain features that make it highly advisable for developing countries, in addition to the fact that the mean heat reservoirs are located within this group of nations

[en] The use of the geothermal energy for energy production is reviewed for different countries. The basic schemes for a geothermal power plant are given. A system with combined cycle (ORMAT GCCU) is described. In Bulgaria, two sources of thermal waters are identified as suitable for geothermal energy production

[en] This study examines on how to improve the performance of dry-steam geothermal power plants in Kamojang by utilizing the binary system. The main data taken in this research is the temperature, pressure and mass flow collected from the plant’s operational data. It is then analyzed using the thermodynamic method and Engineering Equation Solver (EES). Results from the analysis showed that the net power output is about 48,865 kW. The first law efficiency increases from 16.45% to 19.44%, while the second law efficiency increases from 18.69% to 28.75%. (paper)

[en] Steamboat Envirosystems, LLC (SELC) was awarded a grant in accordance with the DOE Enhanced Geothermal Systems Project Development. Atlas-Copco Rotoflow (ACR), a radial expansion turbine manufacturer, was responsible for the manufacturing of the turbine and the creation of the new computer program. SB Geo, Inc. (SBG), the facility operator, monitored and assisted ACR's activities as well as provided installation and startup assistance. The primary scope of the project is the redesign of an axial flow turbine to a radial inflow turboexpander to provide increased efficiency and reliability at an existing facility. In addition to the increased efficiency and reliability, the redesign includes an improved reduction gear design, and improved shaft seal design, and upgraded control system and a greater flexibility of application

[en] The Philippine experience in risk assessment and management is more pronounced in the field of energy systems. This particular study focuses on the evaluation and management of pollutant emission from a geothermal power plant. It embraces two main methodologies 1) the systematic calculation of the risks impacts of the energy systems to human health and to the environment, and 2) the evaluation of cost-effectiveness of risk reduction schemes. Presented in detail is how the researchers resolve the problems and the approach perceived as necessary for an effective risk management. (ELC). 12 refs.; 5 tabs.; 3 figs

[en] Geothermal power development in New Zealand first began in the mid-1950s, and there is the potential for the supply of up to ten per cent of the country''s power needs. New Zealand already has over 300 MW of installed geothermal capacity. In recent years, deregulation of the power industry has encouraged further development, and two new plants entered commercial operation late last year. (author)

[en] Highlights: ► An introduction to AHP technique was made. ► Application to AHP was given to define source and community importance. ► Importance of energy sources were found. ► A policy for the sample district was made according to the importance matrix. ► Solar and geothermal sources has highest importance with natural gas support. - Abstract: Energy resource planning for a district in the built environment is a challenging issue for the authorities. They have to take many criteria into account in order to derive sustainable, robust, and long-term energy policies. Among these criteria authorities have to look at the alternatives from different point of views, such as the environmentalists, industry, local community, and local authorities of that district. In this study, an Analytical Hierarchy Process (AHP) method was developed in order to facilitate energy resource planning activities. This method was applied to the district of Aydin in Turkey. Hypothetical results showed that solar energy investments has the highest priority and can be realized by local residents and government, while industry and government can make investments for geothermal power plants and de-centralized lignite power plants using clean technology.

[en] The Oregon DOE (ODOE) compiled available public information documenting geothermal power plants in the US. ODOE did this work for Bonneville Power Administration (BPA). Work began in early 1991 and was complete in March 1992. Database and example report files were sent to BPA at that time. Data covers both construction and operating experience at plants. Interview data supplemented reports. The paper discusses trends regarding development timing, size, suppliers and other characteristics

[en] This book highlights research and industry developments of geothermal energy for 2000 and 2001

[en] At Mt Amiata (Italy) geothermal energy is used, since 1969, to generate electricity in five plants with a nominal capacity of 88 MW. Anomalous levels of mercury characterise geothermal fluids of Mt. Amiata, an area renowned for its vast cinnabar deposits and for the mercury production carried out in the past. Mercury emission rates range from 300 to 400 g/h, or 3-4 g/h per MW electrical installed capacity. These emissions are coupled with a release of 7-8 kg/(h MW) of hydrogen sulphide (H₂S). Mercury is discharged as Hg''0 gaseous species and reaches the atmosphere with the non-condensable gas fraction. In this fraction CO₂ is the major component (94-98%), H₂S is around 1% and mercury concentration is as high as 1-10 mg/Nm''3. Leaves of a spontaneous grass (Avena sterilis), at the end of the vegetative cycle, were used as mercury bioconcentrators to map deposition near geothermal power plants and to calculate the corresponding average levels of Hg''0 in the air. Direct measurements of mercury and hydrogen sulphide vapours in the air reached by power plant emissions showed a ratio of about 1-2000. This ratio was applied to calculate average levels of hydrogen sulphide starting from mercury deposition mapping: typical concentrations of mercury and hydrogen sulphide were of the order of 10-20 ng/m''3 and 20-40 ^mu^g/m''3, respectively. (author)