NIL, Sarulla, Indonesia

The NIL 1 and NIL 2 geothermal power plants, are a part of the Sarulla Geothermal Power Project in the Tapanuli Utara district, North Sumatra province, Indonesia. The project has been labelled the “world’s largest single-contract geothermal power project” to date with a capacity of 3 x 110 MW. It is owned and will be operated by Sarulla Operations Ltd (SOL), a consortium of Medco-Ormat-Itochu-Kyushu.


The geothermal fields are known as Silangkitang (“SIL”) and Namora-I-Langit (“NIL”) reservoirs. The construction of phase one started in 2014 and its commercial operation started in 2017. The other two phases were commissioned in the second half of 2017, and 2018. The first unit of 1x110 MW, SIL 1 was constructed at Silangkitang and the other two units of 2 x 110 MW are located at Namora-I-Langit.


Hyundai won the EPC contract for the project and subcontracted Mannvit and its Indonesian partner CBN. The power plant uses a so-called Geothermal Combined Cycle Units (“GCCU”) which are more efficient than conventional flash type geothermal power plants. The condensate steam and the brine water is re-injected underground using over 190 injection wells to maintain a sustainable geothermal resource.


  • Review of process flow- and P&I diagrams
  • Hydraulic calculations (steady state and dynamic)
  • Review of control- and operation philosophy
  • Review of Hazop study
220 MW 
Power plant
330 MW 
Total capacity