The 220MW Rantau Dedap geothermal power plant is being developed in South Sumatra Province of Indonesia. Credit: Engie.
The first exploration well at Rantau Dedap was spud on 3 February 2014. Credit: Supreme Energy.
Perusahaan Listrik Negara (Persero) will buy the electricity generated by the Rantau Dedap geothermal project under a 30-year power purchase agreement signed in November 2012. Credit: Supreme Energy.

The 220MW Rantau Dedap geothermal power plant in South Sumatra, Indonesia, is being developed by PT Supreme Energy Rantau Dedap (SERD), a special-purpose company formed by a joint venture of Marubeni (35%), Supreme Energy (30%) and Engie, formerly GDF Suez (35%).

A pre-feasibility study for the geothermal prospect was completed in March 2009, and the first spud-in exploration drilling was conducted in the RD-B1 geothermal working area on 3 February 2014. The plant is expected to begin operations in 2018.

The geothermal project is a part of the second 10,000MW accelerated development programme initiated by the Indonesian Government in 2010 (Fast Track Programme 2). It is anticipated to provide clean electricity for approximately 490,000 households, while offsetting approximately 1.1 million tonnes a year of carbon dioxide emissions.

The Indonesian geothermal power project includes the construction of two 110MW units. Geothermal concession for the project was awarded in December 2010, while the price approval and assignment from the minister of energy and mineral resources were obtained in September 2011.

Rantau Dedap geothermal project location

Muara Laboh geothermal power plant is a 220MW greenfield project coming up in Muara Laboh, Solok Selatan Regency, West Sumatera Province of Indonesia.

The project site is spread over South Sumatra Muara Enim, Lahat and Pagar Alam regencies and is located approximately 225km from South Sumatra’s capital city, Palembang. It extends over 35,440ha, at an elevation ranging between 1,000m and 2,600m, within the Bukit Besar volcanic complex.

Technology and plant make-up

The project will use direct contact condensing steam technology with evaporative cooling towers to generate geothermal power. Cooling water for the cooling tower will be supplied directly by the geothermal fluid extracted from the deep geothermal reservoir. Water for well drilling and other ordinary usages, such as utility water and wash-up of surfaces, will be collected from a nearby river.

A steamfield above ground system (SAGS) will be installed to interconnect the production and re-injection wells with the power plant. The SAGS will consist of a piping system to convey the two-phase geothermal fluid from production well-pads to separator vessels, which will produce steam and brine streams. The separated steam flow will be conveyed to the power plant steam interface by means of a piping system.

A scrubbing system will be installed at the plant steam interface to produce steam, whereas the separated brine from the separator vessels will be conveyed to the re-injection pipelines through a separate pipeline.

Rantau Dedap power project development

The Rantau Dedap geothermal power project is proposed to be developed in two phases. The first phase will include the geothermal resource exploration and drilling, while the second phase will encompass the steamfield development and power plant construction.

Four wells will be drilled during the exploration stage, while an additional 18 wells will be drilled during the construction phase. The final 22 wells are expected to generate 220MW net electricity at a design load factor of 90%. Further, six injection wells are proposed to be formed to discharge the condensed water into the geothermal reservoir.

SERD started exploration drilling at the RD-B1 geothermal working area Rantau Dedap in February 2014. Five wells were drilled by the end of 2014.

Off-take of power generated at Rantau Dedap

“It is anticipated to provide clean electricity for approximately 490,000 households, while offsetting approximately 1.1 million tonnes a year of carbon dioxide emissions.”

On 12 November 2012, SERD entered a 30-year power purchase agreement (PPA) with the state-owned Perusahaan Listrik Negara (Persero) to sell the electricity generated by the geothermal power plant.

Project financing

Asian Development Bank (ADB) is providing $50m in financial support, under the Clean Technology Fund, for the Rantau Dedap geothermal project.

Key players involved in Rantau Dedap

Leighton Contractors Indonesia was engaged to conduct civil infrastructure works at the Rantau Dedap geothermal power project. Under the $32m contract, which was completed in 2014, Leighton upgraded and widened 14km of existing roads, constructed 35km of new access roads, five well pads and an accommodation camp, in addition to the supply and installation of a water/brine distribution pipeline.

Hadiputranto, Hadinoto & Partners (HHP), the member firm for Baker & McKenzie in Indonesia, participated in the negotiation of the long-term PPA with Persero, and the business viability guarantee letter with the ministry of finance.