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

Te Mihi Geothermal Power Station

Te Mihi Geothermal Power Station

The Project

Wairakei Power Station commenced operation in 1958. The maintenance and refurbishment costs, combined with the expectation that continued operation using river water for cooling would not be possible, prompted evaluation of options to maximize future generation while meeting environmental constraints. Members of Thorndon Cook Power staff worked with Contact Energy from the early 2000’s to develop and optimise concepts from the ground up to refurbish or replace the existing Wairakei Power Station.

In February 2011 Contact Energy committed to the construction of the Te Mihi geothermal project, reflecting Contact’s view that geothermal energy is currently New Zealand’s most cost effective source for new baseload generation. The project consisted of two units of 83MW each) which were constructed near the 52 year old Wairakei geothermal power station, northwest of Taupo. On completion in 2014, the project allowed approximately 45 MW of the existing Wairakei geothermal station to be decommissioned, resulting in a net increase in output from the combined Te Mihi and Wairakei stations of about 114 MW.

Our Role

Prior to Contact Energy committing to the construction of the project, staff from Thorndon Cook Power were involved in performing the following:

  • completed conceptual design and optimisation studies
  • prepared EPC technical bid documents
  • assisted Contact Energy in the selection and contract conformation for supply of the steam turbine/ generator/condenser equipment
  • prepared a FEED study as part of the successful EPC submission.

Thorndon Cook Power staff were then employed by the Joint Venture (JV) for the delivery of the EPC (Engineer, Procure, Construct) contract for the Te Mihi power station, and had major involvement in the project.

Our primary role within the fully integrated JV, was to deliver the engineering and design for the project with ongoing technical support to the procurement and construction activities.

Thorndon Cook Power staff were responsible for all the detailed power plant design, including conceptual design, plant optimisation, BOP detailed Engineering, performance guarantees, preparation of sub vendor packages, design drawings and documentation.

Thorndon Cook Power staff were also heavily involved during the plant commissioning and performance testing.


Officially opened: 14 August 2014 Cost: $623 million

Generation: 166 megawatts, enough to power about 160,000 homes

Peak workforce: About 500 people Local spending: $60 million Construction started: February 2011

First 3-flow geothermal turbine in the world (3 exhausts into condenser) significantly lowering turbine exit losses


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

conceptual engineering, feasibility studies, including economic analysis, front end engineering design, detailed design, project planning and project management, tendering and procurement, site construction supervision, commissioning and start-up, technical assistance during operation

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