Thorndon Cook Power
Thorndon Cook Power
Thorndon Cook Power
Nasulo Geothermal Power Station

Rotokawa Steam Purity Improvement

Rotokawa Steam Purity Improvement

The Project

The Rotokawa Geothermal Project, north of Taupo in New Zealand was developed by a partnership between the resource owner, Tauhara North No 2 Trust, and Power New Zealand.

Initial drilling exploration was undertaken in the 1960’s with further development taking place in the 1980’s.

Tenders for supply and installation of a 24 MW combined steam turbine/binary cycle plant were invited in 1995, and the power station was commissioned in 1997.

The Rotokawa Power Station has a combined cycle configuration with a single separator suppling steam to a backpressure turbine STG10. Exhaust steam from the turbine along with steam and brine from the separator supplies four binary ORC units.

In 2014 members of Thorndon Cook Power were engaged to provide engineering assistance to MRP to develop the design and business case for proposed steam purity improvements to the steam delivery to the backpressure turbine.

Our Role

Members of Thorndon Cook Power staff were engaged to perform the work for MRP which included:

  • process modelling
  • assessment and recommendations for modifications
  • prepare preliminary layout of proposed modification
  • P&IDs
  • equipment and piping Material Take Offs (MTOs)
  • pipe stressing
  • equipment process calculations
  • installation methodology
  • preparation of technical specifications and data sheets for vendor quotations


The process modelling allowed various solutions options and scenarios to be tested, evaluated and then refined into the recommended best solution. After discussion and agreement with MRP, a comprehensive set of deliverables were produced in a short time frame to meet the required schedule to prepare the business case.

These included the system layouts, P&IDs, MTOs, and technical specifications complete with datasheets, the extent of which allowed the vendors to provide well defined proposals, benefitting MRP with the most cost effective solution ready for implementation.


process design, mechanical engineering

owner's engineer roles

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