PGE builds reliability into geothermal plant from day one

The operator uses field data to improve long-term performance.

Pertamina Geothermal Energy (PGE) is designing its 55-megawatt Lumut Balai Unit 3 geothermal plant using operating data from its existing facilities, as it seeks to improve long-term reliability before the project starts operating in 2030.

"A baseload geothermal plant cannot be designed only to achieve commercial operation date," Andi Joko Nugroho, operations director at PGE, told Asian Power in an emailed reply to questions.

Instead of treating the project as a standalone development, PGE is using data from its existing geothermal fields on equipment performance, outage patterns, maintenance schedules, and operational risks to guide engineering decisions.

The information is analysed through a reliability, availability, and maintainability assessment that balances long-term performance against capital costs.

The data influences decisions ranging from equipment selection and maintenance access to spare part planning, inspection schedules, and monitoring systems, Nugroho said.

The plant is also being designed with condition monitoring, predictive maintenance, digital asset management, and enhanced diagnostics from the outset.

A computerised maintenance management system and preventive maintenance programme will be established during commissioning, allowing major inspections, turbine overhauls, steamfield maintenance, and coordination with state utility Perusahaan Listrik Negara to be planned before commercial operations begin.

Spare part inventory will also be based on the importance of each component rather than cost alone. Nugroho said Unit 3 would draw directly on maintenance practices, inventory planning, and equipment failure records from PGE's existing Lumut Balai units.

The company is maintaining a stable geothermal resource, ensuring plant equipment can withstand corrosive fluids and mineral scaling, and coordinating operations with the electricity grid.

Although key technologies such as turbine generators, reservoir modelling, drilling systems, and corrosion management still depend heavily on international suppliers, PGE is using the project to transfer knowledge to local engineers.

Staff participate in design reviews, hazard studies, factory testing, site acceptance tests, and commissioning alongside overseas vendors.

Performance will be measured using several indicators rather than a single target, including plant availability, unplanned shutdowns, capacity factor, reservoir performance, steam quality, and lifecycle costs.

Nugroho said the approach is already delivering results. In the first quarter of 2026, electricity production rose 15.2% year on year to 1,370 gigawatt-hours, whilst the capacity factor increased to 90.77% and the availability factor improved to 99.63%.

Joko Sutopo, president director at Sulzer Services Southeast Asia—the regional arm of the Swiss-based rotating equipment maintenance and repair group—said corrosion, scaling, and erosion are amongst the biggest reliability challenges for Indonesia's geothermal fleet as plants operate continuously.

He said Sulzer has introduced specialised materials and repair techniques to extend equipment life, whilst local repair, reverse engineering, and remanufacturing capabilities help reduce outage times by reducing reliance on overseas support and replacement parts.