Mount Salak sets momentum for geothermal station
JAKARTA (JP): Gunung Salak in West Java is setting the momentum for the accelerated development of geothermal resources in Indonesia.
Two new geothermal power stations at Mount Salak with a combined capacity of 110 megawatts (MW), and one with 55v MW at Mount Darajat, about 80 kilometers southeast of Salak, are to be dedicated by President Soeharto today.
An additional capacity of 220 MW is in the pipeline at the Salak power complex.
Indonesia's geothermal resources are, in fact, large and well distributed. The high volcanic activity in the country, allowing magma to ventilate towards the earth surface and the high average annual precipitation, gives place to many exploitable geothermal resources in the form of high pressure underground reservoirs of hot water and steam.
Surveys conducted by the government along the volcanic belt have assessed a geothermal potentials up to 15,000 MW, probably the largest in the world.
Detailed prospecting and inventories of promising areas show an immediate availability of 1,400 MW and a total of 4,000 MW in the medium term.
Since geothermal constitutes a clean, environmentally viable and alternative source of energy it has been given high priority.
However, geothermal electricity, unlike electricity from fossil fuels, cannot be ordered: it must be developed. A geothermal field must be discovered, tested and developed in order to produce power.
Attention to geothermal energy in Indonesia has a long history. As early as 1918, on the basis of the successes already achieved in Italy with the exploitation of this source, proposals were made by Z.F. van Dijk to explore geothermal energy in Kamojang, West Java.
But, it was only in 1926-1928 that five shallow exploration wells were drilled at Kamojang by the Netherlands West Indies Volcanological Survey.
First plant
The state oil and gas company Pertamina, in cooperation with Geothermal Energy New Zealand Ltd., drilled 15 wells in Kamojang from 1974 to 1979 and the state electricity company PLN completed the construction of the country's first commercial geothermal power plant in 1983 with a capacity of 30 MW at Kamojang financed by the New Zealand government.
Then in 1988 Pertamina and PLN expanded its capacity to 140 MW, with the Word Bank financing. In parallel, a second major geothermal development was started in the Gunung Salak area.
Since 1982, Unocal of the United States, in a joint venture with Pertamina, invested in the development of the steam field of Gunung Salak and started the setting of exploratory wells in the area and the construction of infrastructure.
The Salak geothermal reservoir is of the "liquid dominated type" which means that the geothermal fluid coming up the wells is a mixture of water and steam at a pressure of eight bars and a temperature of 280 degrees. The gas content is minimal, so is the content of minerals: which are both good features.
The wells feeding the mixture of steam and water to the power plant total nine, scattered over a wide area. A network of pipelines, the gathering system, conveys the geothermal fluid to the power plant site, where the steam is separated from the water in special separators, before entering the turbines.
The financing for the construction of the power plant for PLN was eventually made available through a soft loan from the Italian government in 1990 which covered the whole foreign costs of the plant.
Ansaldo
A contract was awarded by PLN to Ansaldo Energia, the main Italian contractor and manufacturer for power generation, for the construction and supply of the power plant on a turn-key basis. The power plant consists of two units each with 55 MW, and was built according to the most updated technology in this field.
The turbines are of the highly efficient impulse type, single cylinder, double flow, manufactured using special steel which is suitable in a corrosive environment. The plant automation is highly sophisticated: the control and supervisory system of the power plant is based on microprocessor technology with a distribution architecture and is equipped with an advanced operator interface.
The switchgear is of the gas insulated type, highly compact, particularly suitable for space and environmental conditions. The condensers, of Ansaldo design, were fabricated by PT Barata. Barata was also the mechanical erector.
The first 55 MW unit has been in full commercial operation since June 1994 and the second 55 MW unit since August 1994. The actual power output is 117 MW, exceeding the 110 MW guaranteed.
The future development in the Salak area will be the extension of the present plant with one more unit -- unit no. 3 with 55 MW, for which a new contract will be awarded by PLN to Ansaldo, bringing the capacity of the power plant to 165 MW. The financing of this unit will be derived from an Italian export credit.
Total project
In addition, a new power plant in the same area comprising unit four, five and six for an additional 165 MW, will be built as private power by Unocal and Pertamina with the total project concept under the build, operate and transfer scheme.
By 1997 the Salak area will produce 330 MW and will become one of the largest geothermal fields in the world.
It is worthwhile mentioning that the industrial activity in geothermal sector had its origins in Italy. The harnessing of endogenous steam for production of mechanical energy at the geothermal field of Larderello dates back to 1894 and the electrical power production from the first steam turbine- generator unit with a capacity of 250 kilowatts started in 1913.
According to the records of the Italian State Electricity Board, which is also responsible of the geothermal fields, the capacity of the plants operating in Italy (39 units), is about 900 MW.
Ansaldo Energia has furnished the equipment for all geothermal power plants in Italy since 1913 until today, establishing a world record of more than 70 years of experience in the very specialized field of geothermal turbines. (vin)