Indonesia - Electricity Generation

Geothermal resources in the country are associated with volcanoes along Sumatra, Java, Bali and the islands in eastern part of Indonesia, with an expected potential of about 28 GWe composed of 312 geothermal potential locations. The current geothermal fields are operated from 10 locations: Darajat (260 MWe), Dieng (60 MWe), Kamojang (200 MWe), Gunung Salak (377 MWe), Sibayak (11 MWe), Lahendong (87 MWe), Wayang Windu (227 MWe), Ulu Belu – South Sumatra (110 MWe), Ulumbu – Flores (5 MWe) and Mataloko (2.5 MWe). The installed electrical capacities consist of 1,340 MWe, with short-medium term development for the year 2025 of about 6,000 MWe (correspondingly to 5% of the energy needs of the country). About 440 MWe are in advanced construction stage in five plants at Sarulla and Lumut-Balai (Darma and Gunawan, 2015).

Development since WGC2010: 3 new areas (Ulumbu, Mataloke and Ulubelu), for a total additional capacity of 143 MWe.

Installed capacity 1,340 MWe               
Geothermal Electricity 9,600 GWh/y

Source:  Ruggero Bertani, Geothermal Power Generation in the World 2010-2014 Update Report

Installed geothermal generating capacity (December 2009) in MW

Gunung Salak 375.0
Wayang Windu 227.0

After the economic crisis of the recent past, this country is starting a very important geothermal activity with important power plant construction and exploration, strongly supported by Government, through regulation and policies. There are good perspectives and positive signal from the market, still to be confirmed over the next months

The new plant commissioned since 2005 are
110 MW in Darajat,
117 MW at Wayang Windu,
2x20 MW at Lahendong,
60 MW at Kamojang, and
10 MW at Sibayak,
reaching the total installed capacity of about 1.2 GW (including also the upgrading of the six units of Salak, 60 MW and two in Darajat, 15 MW), confirming Indonesia at third position in the world ranking.


Lahendong: three 20 MW units have been installed (the first in 2002, the other two in 2008 and 2009 respectively) and further 20 MW under construction, following a development plan of additional 60 MW; after the past negative experience in binary plant in Indonesia (only an old 2.5 MW experimental unit, which has never been operated), the first new generation 7.5 MW binary bottom unit is planned in this field for year 2012. The field is operated by Pertamina Geothermal Energy and the national electrical utility PLN.


Sibayak: the exploitation started in 1996, with a small 2 MW unit. Two new units, for 13.3 MW in total has been commissioned in 2007; further 10 MW are planned, if the expansion of the production area will be confirmed after the surface exploration activities (Pertamina Geothermal Energy).


Kamojang: a new addition of 60 MW has been commissioned in 2007, increasing to 200 MW dry steam plants. It was the first exploited geothermal field in Indonesia, where in 1978 a small 250 kW unit has been commissioned. The three units performed quite well during their entire operative life (since 1982 and 1987). Moreover, there are additional 60 MW currently under construction (Pertamina Geothermal Energy and PLN). 

Dieng: one 60 MW unit has been installed in 1998, first step of a four-plant project. After the economic crisis and as a result of the arbitration, the ownership of the field has been transferred to Geodipa and the plant started its operative life. Two more 55 MW plants have been planned. Wayang Windu: in 2009 a new 117 MW has been added to the old 110 MW, in operation since 2000. The field is operated by Star Energy, an Indonesian oil company. Drilling activity and resource evaluation are on going, for almost double the production from the field.

Gunung Salak: no new plant since 1997; the six 65 MW similar units are currently operated 20% above the reference installed capacity (55 MW), due to the power shortage in Java/Bali, for a total of 375 MW. The BOT scheme will end its effect in 2012, and the three units currently operated by Chevron will be transferred to PLN.

Darajat: the geothermal resource is vapor dominated, in exploitation since 1994, and a new unit of 110 MW has been commissioned in 2008; further development for additional 110 MW are on going. The field and power plant are operated by Chevron since 2006, and the two old units have been upgraded of 15 MW in total.


In the Bedugul field the Bali Energy Ltd. confirmed the development plan for 175 MW, with a first 10 MW pilot plant and three 55 MW units, for the exploitation of the liquid reservoir at 280-320°C and 1,500-2,000 m depth.

New Areas

On Sarulla, in North Sumatra, the development of three 110 MW projects has been recently assigned to an international consortium, including Medco Power, Itochui, Ormat, Kyushu Electric and Pertamina as field operator. The expected ambitious schedule is to reach 330 MW in 2013. 

In Central Sumatra, Hulu Lais field have been explored and a development plan has been launched. 

In Ulu Belu, South Sumatra, the good liquid reservoir at 240-260°C is under advanced exploration stage, and four 55 MW unit will be commissioned in the coming years. The same development is scheduled for the similar area of Lumut Balai and Sungai Penuh, where the first units are expected for 2012.

In Pathua, Java, the original exploration done before the crisis identified a good resources, which has been transferred, after the arbitration, to Geodipa. Three 60 MW units are planned. In the nearby zone of Karaha Bodas, 140 MW are scheduled, with the first 30 MW in 2012. 

Finally, in Sulawesi two new projects in Kotamobagu and Tompasu identified a 250-290°C reservoir; 120 MW in total are planned.

In total, an impressive amount of project for reaching the expected target of 3.5 GW in 2015 is on going, strongly supported by government, foreign and domestic investors. It is a very challenging opportunity: to become the first geothermal country in the world, tripling the present capacity in only five years. However, this tremendous increase in installed capacity in only five years is unlikely. A more solid value in the range of 2-2.4 GW can be considered as an affordable and realistic goal. In the last five years term, the installed capacity increased of 400 MW, corresponding to about 50%.

Taken from Ruggero Bertani’s paper, " Geothermal Power Generation in the World 2005–2010 Update Report ", published inProceedings of the World Geothermal Congress 2010, Bali, Indonesia, 25-29 April 2010.