“Geothermal energy laws” that govern the procedures of geothermal resource development and stipulate the rights and duties of geothermal resource developers in major countries were surveyed. The survey was carried out by collecting relevant laws and papers through the Internet. Each county has its own “geothermal energy law”. These laws were compared from the view points such as the objective of the law, the ownership of the resources, the types of licenses, the licenser, the licensee, the setting of licensed area, etc. Geothermal energy laws in other countries may be great reference when Japan considers enhancing its own legal framework to promote geothermal energy development.

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We conducted a geochemical survey of hot springs and related water in an area 20 km north to south and 30 km east to west at the Kotamobagu geothermal field, northern Sulawesi, Indonesia. Thirty one water samples from hot springs and river water were collected at elevations between 173 m and 1438 m asl and analyzed for their chemical compositions and stable isotopes of water. Rain water was also collected using an open air rainwater collector from five locations with elevations from 556 m to 1500 m between March and June 2010. Most of the hot spring waters of HCO₃ and hybrid type have a neutral pH, and their stable isotope values of water are distributed along the global meteoric water line (GMWL), indicating that they are of meteoric origin. However, the acidic water samples deviated from the GMWL. One sample (MUAH-16) collected near a fumaroles on the summit of Mt. Muayat, indicates of SO₄ type, implying steam-heated water. Thus, the deviation of the acidic water sample from the GMWL is caused by evaporation of meteoric water at shallow depth and/or on the surface. Sample LOBH-10 has a neutral pH and shows a δ¹⁸O shift from the local meteoric water line. This sample is located near the edge of the field and the shift may be caused by reaction with marine origin rocks.

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