Thorndon Cook Power
Thorndon Cook Power
Thorndon Cook Power
Mahanagdong Geothermal Power Station

Lahendong 1x5 MW EPC Engineering

The Project

The planned Lahendong Small Scale Geothermal Power Plant consists of an existing well pad and wells supplying steam to a 1 x 5MW gross Geothermal Power Plant (GPP) located on a nearby well pad.

The steam from the FCRS is supplied from three production wells on one well pad, and from one well on the well pad which contains the GPP area. The steam from the wells is supplied via an existing cyclone separator. The steam is combined and flows to the scrubber located in the GPP area. Separated geothermal water is directed to existing silencers for discharge to ponds.

The project objective as presented in the bid documents was for a simple lowest cost plant that can deliver the 5MW Gross reliably, with steam consumption no more than the specified figure.

The single flow steam turbine was designed and supplied by Toshiba. The GPP balance of plant includes turbine exhaust duct, horizontal direct contact condenser, hotwell pumps, counterflow cooling tower and basin, auxiliary cooling water pump, hybrid non-condensable gas removal system, drains system and blowdown tank to existing condensate pond.

Our Role

Thorndon Cook was engaged by JFE to provide engineering service for the bidding of the Lahendong Small Scale Geothermal Power Plant, including FCRS. JFE’s turbine supplier, Toshiba, had already selected the design parameters for the single flow turbine (particularly exhaust pressure) and Thorndon Cook was responsible for the rest of the GPP design and specification.

Utilising its in-house geothermal power plant modelling software, Thorndon Cook first carried out power cycle optimisation to select the process design parameters of the main equipment, that produced the overall lowest cost plant that met the output and steam consumption required.

The process design parameters were then used to complete preliminary design to determine size, capacity and specification of the major equipment and materials for JFE’s cost estimation. This included well pad separator, steam scrubber, condenser, cooling tower, gas removal system, hotwell pumps, auxiliary cooling water pump, control valves and associated piping and fittings.


Thorndon Cook delivered a set of documents allowing JFE to bid for the project, including documents for inclusion with the technical bid submission, as follows:

  • Process Flow Diagram with optimised heat and mass balance
  • Process and Instrumentation Diagrams
  • Datasheets and specifications for piping and major equipment
  • Painting and insulation specifications
  • Sizing calculations for vessels, pipelines and pumps
  • Control Valve and Instrument Lists, Data Sheets and Specifications
  • Project and process description
  • Foundations dimension and load (including piping foundations)
  • GPP and FCRS General Arrangement


process design, mechanical engineering, civil and structural engineering, control and instrumentation, project/program management

conceptual engineering, front end engineering design

stress analysis

conceptual engineering, tender preparation and evaluation

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