Ngawha Geothermal Power Plant Expansion

Client: Top Energy Ltd
Date:  2013 – 2015

The Ngawha geothermal power plant presently produces ~70%  of the electricity consumed in the Far North District and is the only municipal power plant north of Auckland.  The power plant utilises natural heat energy from the Ngawha Geothermal Reservoir, which is situated between 1km and 3km below ground level.  The reservoir fluids are typically 230˚C in temperature.  Due to predicted demand increases, Top Energy is proposing to expand the geothermal electricity generation capacity at its existing Ngawha power station by constructing two new 25mw power stations.  We were engaged by Top Energy to complete a hydrogeological and hydro-geochemical study and effects assessment for the Ngawha Geothermal Power Plant expansion consent application.

Works included the development of a robust hydrogeological and geochemical conceptual model as well as a semi-quantitative geochemical mixing model and water budget to predict potential effects on geothermal springs and surface features neighbouring the plant.  This was a high profile project amongst the local Iwi, community and business groups associated with the commercially used hot springs.  Our people and work had a key role in the consultation and negotiation process.  Consent for the project was granted in 2016.

Key Aspects:

  • Hydrogeological & geochemical conceptual model development
  • Water budget and geochemical assessments
  • Preparation of technical effects assessment report
  • Evidence presentation and consent condition advice

Client: Top Energy Ltd
Date:  2013 – 2015



A conceptual site model diagram developed for the assessment, consultation and consent application.
One of the many geothermally influenced streams in the region for which potential effects from the proposed expansion were assessed by PDP.

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