Interest in geothermal energy originated in Iran when James R. McNiff, a United Nations geothermal expert visited the country in December 1974.In 1975, a contract among the Ministry of Energy, ENEL (Entes Nazionale per L' Energia Elettrica) of Italy and TB (Tehran Berkeley) of Iran was signed for geothermal exploration in the northwestern part of Iran.In 1983 the result of investigations defined Sabalan, Damavand, Khoy-Maku and Sahand regions as four prospected geothermal sites. From 1996 to 1999 countrywide geothermal energy resource exploration project was carried out by Renewable Energy Organization of Iran (SUNA) which belongs to the Ministry of Energy (MOE) and 10 potential areas were indicated additionally. Geothermal potential siting project by using Geographic Information System (GIS) was carried out in Geothermics laboratory of Kyushu University in 2007. The results of the project indicated 8.8% &Iran as prospected geothermal areas in 18 fields.Across these 18 regions, Sabalan region was selected for the first geothermal area for detailed explorations. Since 1996, feasibility studies to justify exploration drilling and to estimate the reservoir capacity in the Sabalan regions have been carried out by Sinclair Knight Merz Ltd (SKM) from New Zealand From 2002 to 2004 three deep exploration wells were drilled for evaluation of subsurface geological conditions, geothermal reservoir assessment and response simulation. Two of the wells were successful and maximum temperature of 240°C at a depth of 3200 m was recorded.As a result of the reservoir simulation, 55 MW power plant is projected to install in the Sabalan field as a first geothermal power generation. To supply required steam for the geothermal power plant (GPP) 17 deep production and injection wells are planed to drill.At this time the constructing of the well pads is carried out.It has been planned to start the drilling activity in 2008.
Geothermal activity has been considered to have close relation with volcanic activity, but this relation is not examined so much.This paper examined the relation by reviewing the following two aspects. The first aspect is on the difference of geothermal activity. Some volcanoes have intense geothermal activity, while other volcanoes have no geothermal activity. This difference was found to depend on the stress field around volcanoes.In tensile stress field, magma can easily create its path to ascent and secure certain space to store. The second aspect is on the variety of precursor of eruptions including failed eruptions. For instance, Sakurajima Volcano frequently has eruptions after seismic swarm and/or ground deformation. In Asama Volcano, similar phenomena have been observed until eruptions in 1973. On the other hand, eruption has not occurred in Iwate Volcano, though many precursory phenomena such as deformation of volcanic body and increase of seismic activity indicating magma intrusion were detected.Expansion of geothermal activity was detected just on the hypocenter zone. In recent activity of Asama Volcano, the correspondence of the seismic swarm and the eruption has changed to be unclear and the prediction of the eruption turned to be difficult. Increase of geothermal activity is frequently observed after magma intrusion associated with seismic swarm, but no magmatic eruption occurs in many cases and phreatic eruptions occur in some time. These differences originate in the variety of easiness of magma ascent. From the above review, this paper proposes the following idea; volcanic activity has two end members depending on the easiness of magma ascent.The type of volcanic activity will be ‘Eruption dominant’ (ED) when the magma easily ascends to the ground surface, while it will be ‘Geothermal activity dominant’ (GD) in the opposite case.Various kinds of volcanic activities are defined between these end members. The easiness of magma ascent depends on some certain conditions.This paper indicates three possible factors; regional stress, density difference between magma and medium, and degassing from magma. Research on geothermal activity and volcanism is requested to examine these factors, because this idea may present us more systematic understanding of volcanism.
The research and development on geological disposal of high-level radioactive waste from the atomic power generation has been carried out in the Horonobe field, the north-western Hokkaido.In the Horonobe field, investigations of 8 boreholes were carried out as the Horonobe Underground Research Laboratory Project by 2004. These investigations clarify the diagenetic mineralogy and water chemistry, and show that the geology comprises the diatomaceous sediments containing pyrite, calcite and siderite as authigenic accessory minerals, and that the groundwater is a mixture between meteoric water in shallow depth and saline water in deep underground. Relative abundance of pyrite and carbonate is estimated by X-ray diffraction analyses, mode analyses of thin section, and whole rock compositions of SO42, TIC (Total Inorganic Carbon) and (Fe24-/total Fe).Based on the mineralogical analyses, the mineral fronts where relative abundance of the minerals abruptly changes are confirmed.Comparing the mineral fronts with the corresponding water chemistry, the mineral fronts of 2 boreholes in the western part of the field are situated in the saline water zone, but these of other boreholes are situated in the meteoric water zone. Assuming that pyrite and carbonate are stable in the saline water zone because these minerals abundantly occur in the saline water zone, the mineral front in the meteoric water zone is supposed to be remained in spite of water/rock interaction. The occurrence of the mineral fronts in the respected water zones would be attributed to kinetic interaction, suggesting that saline water is discharged upward in the western part of the field, and that meteoric water is recharged downward in other area.
We have developed a numerical model of Geothermal Heat Pump (Geo HP) Systems as an element in the simulator of Integrated Renewable Energy Systems (TRES). The numerical model of Geo HP systems consists of three parts;one is heat extraction fluid in U-tube, the other is layer around the U-tube, and the other is heat pump. The model, which represents temperature variation of heat extraction fluid, is based on the one-dimensional advection-diffusion equation and the heat flow equation between the fluid and the layer. The model, which represents temperature variation of layer, is based on the equation of heat conduction in the cylindrical coordinate system.The model, which represents power variation of heat pump, is based on the capacity diagram released from the heat pump manufacturer. We have confirmed the feasibility of developed model of Geo HP systems by comparing the data calculated from the model of Geo HP systems with the real data of temperature of heat extraction fluid during the thermal response test under the condition of constant heating. It has been revealed that the calculated temperature using the model well agrees with the measured temperature profile, even though there are some inconsistencies around the beginning and after the end of heating due to the simplified model. Therefore, we have reached the conclusion that the developed model of Geo HP systems can represent the dynamic behavior of GeoHP systems enough to use for the IRES simulator.