Update on Geothermal Utilizations in Thailand

ABSTRACT There are one hundred eighteen hot spring manifestations in Thailand, exposed in the north and extended towards western and southern Thailand, with surface temperature ranges of 40-100°C. Thermal water is clear, but with white algae and white, yellowish and reddish of carbonate, sulfur and iron can be envisaged as spotted on ground surface. Chemical analysis indicates that the thermal water contains various concentrations of dissolved chemical species e.g. pH ranges of 6.4-9.5, conductivity ranges of 225-26,500 microsiemen/cm and fluoride ranges of 0.005-20.4 ppm. There are 9 hot spring areas in southern Thailand exhibiting brackish or saline water. Preliminary studies of hot springs indicated different degree of mixing of thermal water with country rocks. Chemical compositions of hot spring not equilibrium caused some geothermometer calculations using Na, K Ca and SiO2 to be unreliable. Almost all geothermometer calculations provide a similar reservoir temperature where the five highest reservoir temperatures range from 180-210°C, namely San Kamphaeng, Fang, Mae Chan, Sop Pong and Mae Choke hot springs. Hot spring manifestations can be classified related to rock types into two types as hot springs manifest in granitic rocks and hot springs manifest in sedimentary or metamorphic rocks. Heat sources anticipate as combination of five parameters. First, hot springs manifest in granitic rocks, receive heat exchange from thermal water and country rocks. Second, hot springs manifest in granitic rocks, comprise higher concentration of radioactive elements than world average, receive heat from decay of radioactive element. Third, hot springs manifest along high angle dipping fractures and faults, receive heat from tension between fault plane. Forth, hot springs manifest along N-S normal faults occurred wide spread along Tertiary basin in Thailand, receive heat from faults. Fifth, hot springs manifest in high heat flow area caused by thinner crustal thickness, receive heat from shallower hot intrusive rocks. Geothermal resources in Thailand are classified into low-medium enthalpy. Hot spring manifestation in northern Thailand provides higher potential than in the other part. Many expert teams point out that there are suitable possibilities for small scale power plant i.e. 1-10 MWe. Hot springs manifest in western and southern Thailand are classified as low enthalpy and suitable for agricultural, tourist attraction sites and therapy bath. Currently, geothermal utilization as binary cycle power plant is 0.3 MWe and capacity for direct uses is 127.47 MWt. Direct uses are practically restricted to bathing and swimming pool in recreation area and therapy. Most possibilities for future geothermal activities in collaborating between private sector and government sector should be multipurpose utilizations e.g. binary power plant and direct uses drilled at depth less than 1,500 m and reservoir temperature around 130°C