Arun - Sumatra, Indonesia
Arun + Wärtsilä

Reference case

Arun, building an optimum generating system

With a population of nearly 250 million and an economy that has grown at an average of 5.6 per cent a year over the last decade, Indonesia is hungry for power.

To improve electrification and meet a demand that is expected to grow at 9-10 percent per annum in the coming years, much of the new capacity that is being added is in the form of large baseload coal-fired plant. However, building an optimum generating system that can also meet peak electricity demand is a challenge.

The government’s decision to turn to gas to address the issue presented an opportunity for Wärtsilä to demonstrate the benefits of its flexible power generation solution. Aceh Special District in northern Sumatra is one area that needs to strengthen its electricity system to ensure reliable electricity supply up.

Arun will be able to reach full load in 10-15 minutes. Further, because engines can be switched on and off according to load requirements, the remaining engines can run at full power and therefore the plant can maintain maximum efficiency over a much wider load range. By comparison, a gas turbine due to its much larger size would have to operate at part load and thus be much less efficient.

Grid stability has to be improved and more capacity is required to serve the demand peak that occurs once a day for about five hours. When the state utility PLN decided to build the new Arun gas-fired plant to address its needs, it could have opted for open cycle gas turbines. However, after a careful lifecycle analysis, it decided to build a plant based on combustion engines supplied by Wärtsilä. With an output of 184 MW, generated by nineteen Wärtsilä 20V34SG engines running on liquefied natural gas (LNG), it is one of the largest internal combustion engine plants in the country. An engine-based plant has another benefit in that it can be started up and shutdown without impacting maintenance schedules.

The plant’s 19 engines will be split across four blocks of engines (5 + 5 + 5 + 4) housed in two adjacent powerhouses. Radiators for each block are located on the roof, and the entire plant will be controlled from a single control room. As the plant will be used purely for peaking as a grid stabilising plant, it is expected to operate for between 2000 and 3000 hours a year.

Using the Arun plant purely for this purpose has overall benefits for the entire power system. It will optimise the system by enabling PLN’s large baseload plants to stop peaking operation and run at full power, where they are most efficient, all year round. For PLN the savings will be dramatic. Due to rapidly increasing electricity demand, Arun was being built on a fast track basis – only 18 months from contract signing to full commissioning.

Notably, it is the first project where PLN requested the contractor and the equipment manufacturer to arrange financing through export credit. Wärtsilä worked closely with Finnvera and Standard Chartered Bank to secure the loan agreement at attractive interest rates. Wärtsilä’s support in arranging financing has also helped to expedite the project. Arun not only helps to satisfy Indonesia’s enormous appetite for power, but it also serves as a reference for a more flexible way of tackling peak demand and providing grid stability throughout the region.

WhoPT Wijaya Karya Persero Tbk
What19 x Wärtsilä 20V34SG
WhereArun, Sumatra
HowEEQ (Engineered equipment delivery)

This is what we achieved


MW of electrical output


Minutes to reach full load


Months fast-track basis

The Arun power plant will serve to strengthen the Aceh Special District electricity system, ensuring reliable electricity supply to consumers during peak loads.

How we did it

Challenge icon


  • Meet a heavily fluctuating peak demand for short periods
  • Very large operating window required
  • Fast growing demand soon renders current capacity insufficient
  • Currently baseload plants must be used also for peaking
  • Grid stability and reliability issues
Solution icon


  • Wärtsilä 34SG combustion engines capable of daily starts/stops without any impact on maintenance
  • Multiple engine solution with higher efficiency than open cycle GT plants
  • Attractive delivery time, financial and development services
  • Smart Power Generation plants used for peaking & grid stability
  • Internal combustion engines with excellent ramp rates and able to reach full load in 10 minutes
Benefit icon


  • Lower lifecycle costs
  • Can follow load without reducing overall plant efficiency
  • Customer can deliver power faster and start earning on electricity sales earlier
  • More efficient use of baseload plants
  • Grid support

The main details

CustomerPT Wijaya Karya Persero Tbk (PT Wika) (Utility)
TypeWärtsilä 34 gas power plant
Operating modePeak load/stand-by & emergency
Gensets19 x Wärtsilä 20V34SG
Total output184 MW
FuelLNG (Liquefied natural gas)
ScopeEEQ (Engineering & Equipment)
Arun map

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Related press releases

Wärtsilä to supply, operate and maintain five multi-fuel power plants in Indonesia

Mar 28, 2017, 10:03 by Wärtsilä Corporation

A consortium between the technology group Wärtsilä and an Indonesian construction company, PT PP (Persero) Tbk, has been contracted to supply five power plants, totalling 255 MW, to PT PLN, the Indonesian state utility. The consortium will be responsible for the complete engineering, procurement & construction (EPC) of the projects, and will also operate and maintain the power plants for a 5-year period.

The five plants are covered by two separate orders. One order comprises four modular gas cube power plants, totalling 115 MW. The gas cubes will be located in Ternate, Nabire, Bontang and Flores. The second order, a 140 MW power plant, will be located in Bangkanai, in Central Kalimantan on the island of Borneo. All five power plants include Wärtsilä 34DF engines capable of running on multiple fuels, such as liquid fuels and natural gas. This significantly increases the operational flexibility and reliability of the plants. The four gas cube power plants are scheduled to be operational in late 2017 and early 2018, and the Bangkanai plant in late 2018. The orders have been booked in the first quarter of 2017.

The four gas cube power plants are part of a public tender announced by PT PLN last year, and they will provide flexible baseload power to the Indonesian grid. Wärtsilä announced the award of a contract for two similar plant deliveries in December 2016. The Wärtsilä gas cube is a ready-to-use, pre-engineered, modular power plant package especially designed for fast-track delivery with minimal site work. In addition to the short installation time, it can also be easily dismantled and re-installed in another location if required.

The 140 MW Bangkanai phase II power plant will complement an existing Wärtsilä-built gas power plant located in the middle of jungle terrain in Bangkanai. The two plants will have a key role in producing electricity for the Kalimantan grid and helping to meet the area’s growing electricity demand. 

Wärtsilä will take on the daily operation and maintenance of these five power plants, to optimise the performance and production lifecycle of the installations. The five-year operations & maintenance agreement includes expertise areas such as recruitment,  management and training of local personnel,  technical support, maintenance planning, performance monitoring and logistics management, as well as preventive and predictive maintenance to meet local health, safety and environmental requirements.

“These contracts showcase the strength of our relationship with the state utility, PT PLN. The customer values our EPC capability and comprehensive O&M offering. The Bangkanai plant is located in a rather demanding environment and PT PLN knows that we can deliver an EPC on-time, even in such tough conditions. The operations & maintenance agreement supports efficient plant performance and profitability; we can maximise the lifetime of these installations and ensure their availability in a challenging environment.” says Frederic Carron, Regional Director at Wärtsilä.

Wärtsilä and PT PLN have a long and healthy business relationship. The two parties recently signed a MoU to build and develop power generation projects in Indonesia. Wärtsilä’s installed capacity in Indonesia will exceed 3.4 GW during 2017.

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For more information, please contact

Frederic Carron
Regional Director, South East Asia & Australia
Wärtsilä Energy Solutions
Tel: + 65 62 674 685

Bjorn Lindell
Strategic Key Account Director
Wärtsilä Services
Mob. +62 811 850 5175

Jukka-Pekka Niemi
General Manager, Marketing
Wärtsilä Energy Solutions
Tel: +358 50 465 2805


Wärtsilä Energy Solutions in brief
Wärtsilä Energy Solutions is a leading global systems integrator offering a broad range of environmentally sound solutions. Its offering includes ultra-flexible internal combustion engine based power plants and utility-scale solar PV power plants, as well as LNG terminals and distribution systems. The flexible and efficient Wärtsilä solutions provide customers with superior value and enable a transition to a more sustainable and modern energy system. As of 2017, Wärtsilä has 63 GW of installed power plant capacity in 176 countries around the world.

Wärtsilä in brief
Wärtsilä is a global leader in advanced technologies and complete lifecycle solutions for the marine and energy markets. By emphasising sustainable innovation and total efficiency, Wärtsilä maximises the environmental and economic performance of the vessels and power plants of its customers. In 2016, Wärtsilä's net sales totalled EUR 4.8 billion with approximately 18,000 employees. The company has operations in over 200 locations in more than 70 countries around the world. Wärtsilä is listed on Nasdaq Helsinki.

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