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Mitsubishi Power completes retrofit of Indonesia's Darajat geothermal plant

Mitsubishi Power completes retrofit of Indonesia's Darajat geothermal plant

Built World

Retrofit lifts Unit 3 output from 121 MW to 129 MW — the largest single-unit geothermal generator in Indonesia

Today: Retrofit complete, commercial operation starts

Overview

Updated 1 hour ago

Mitsubishi Power finished a retrofit of Indonesia's Darajat geothermal plant and restarted Unit 3 at commercial operation. Output rose from 121 megawatts to 129 megawatts, making the unit the largest single generator of geothermal power in the country.

The project upgraded a steam turbine Mitsubishi first supplied in 2007, replacing internals with more efficient parts instead of building new capacity. Indonesia is leaning on such upgrades to raise its renewable share while electricity demand climbs.

Why it matters

Indonesia gains 8 MW of low-carbon power from a retrofit, not new drilling—a way to stretch geothermal assets without building new plants.

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Key Indicators

129 MW
Unit 3 rated output after retrofit
Up from 121 MW; now the largest single-unit geothermal generator in Indonesia.
6.6%
Output gained from retrofit
8 MW added to the previous 121 MW rating.
8 MW
Capacity added by retrofit
Achieved with operational performance above the contract's guaranteed values.

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People Involved

Organizations Involved

Timeline

2007 October 2026

6 events Latest: Today
Tap a bar to jump to that date
  1. Retrofit complete, commercial operation starts

    Today Milestone

    Unit 3 resumes operation at 129 MW, the largest single-unit geothermal generator in Indonesia.

  2. Completion ceremony and cooperation deal

    Agreement

    Ceremony in Jakarta; Mitsubishi and SEG sign a technical study and cooperation agreement.

  3. BREN secures retrofit funding

    Funding

    BREN signs a $121 million loan to fund the Darajat retrofit and Salak Unit 7.

  4. Retrofit contract awarded to Mitsubishi

    Contract

    Mitsubishi Power receives a turnkey retrofit contract from SEG for Unit 3.

  5. Unit 3 starts operation under Chevron

    Milestone

    Darajat Unit 3 comes online under Chevron Geothermal Indonesia.

  6. Mitsubishi supplies Darajat steam turbine

    Installation

    Mitsubishi Power supplies the steam turbine for what becomes Darajat Unit 3.

Scenarios

1

SEG awards Mitsubishi a second upgrade contract

Possible Resolves by Oct 20, 2027

Discussed by: Star Energy's stated 102.6 MWe expansion target; thinkgeoenergy coverage

The Technical Study and Cooperation Agreement signed at the October 2026 ceremony moves from discussion to a firm contract for further output or reliability work at Darajat. SEG's parent BREN has publicly targeted 102.6 MWe of additional geothermal capacity, and the Unit 3 result gives Mitsubishi a working template to pitch for the next tranche.

2

Wayang Windu Unit 3 reaches commercial operation

Likely Resolves by Q2 2027

Discussed by: PT PLN (Persero); thinkgeoenergy

The 30 MW Wayang Windu Unit 3, which PLN briefed for grid synchronization in October 2026, completes its grid connection and enters commercial operation. Such a step would show the broader Star Energy expansion strategy advancing alongside the Darajat retrofit, signaling that Indonesian geothermal development is moving on both fronts—new builds and upgrades.

3

Darajat Unit 3 output derated under sustained operation

Uncertain Resolves by Oct 20, 2028

Discussed by: Geothermal reservoir analysis in yakugen.com.cn

The 129 MW rating depends on the steam supply from the geothermal reservoir, which typically degrades over time. If steam falls short, the unit may have to run below its rating or require additional make-up wells. The extra 8 MW reflects what the upgraded turbine can do, not necessarily what the reservoir can deliver continuously every hour.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

Mid-2010s

Chevron divests Asian geothermal portfolio

Chevron's geothermal subsidiary operated Darajat Unit 3 from its 2009 startup. A divestment from its geothermal assets in Asia shifted ownership of the field to Star Energy, part of Star Energy's acquisition of the plants Chevron had run in Indonesia and the Philippines.

Then

Ownership moved from an oil major to a dedicated geothermal developer.

Now

Star Energy's focus on wringing more value from existing fields set up the kind of upgrade Mitsubishi completed in 2026.

Why this matters now

Explains why Darajat received a retrofit rather than being sold off or expanded with new units—its owner values output gains from assets already in place.

2007

Original Darajat turbine installation (2007)

Mitsubishi Power supplied the steam turbine for what became Darajat Unit 3, part of a long history of supplying geothermal turbines across Indonesia.

Then

The turbine ran for roughly two decades before the upgrade.

Now

That original installation is what made the 2026 retrofit possible—same machine, modernized internals, using the manufacturer's original design knowledge.

Why this matters now

The retrofit was feasible largely because Mitsubishi built the original equipment, giving it the design data needed to raise output without replacing the whole unit.

Sources

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