Exploration Model & Heat Exchanger within Insulator (HEWI) Model

Petratherm has successfully differentiated itself in the geothermal energy sector through both its innovative Exploration Model and the Heat Exchanger within Insulator (HEWI) Model.

The Exploration Model that aims to find "shallow hot rocks close to market" has been further enhanced with the completion of a comprehensive economic pre-feasibility study and financial model to assess Petratherm's (current and proposed) projects and the projects of competitors.

The Exploration Model aims to optimise the five key economic parameters namely:


  • Temperature differential
  • Drilling depth/cost
  • Flow Rate/circulation
  • Network connection costs
  • Generation plant cost/efficiency and to achieve the lowest cost of electricity delivered to the market while minimising risks.


The Exploration Model has been vindicated by excellent temperature results at Paralana, recording a temperature of 176ºC at 3672 metre depth.  The extrapolated bottom hole teperature at 4000 metres depth is 190ºC ± 1ºC.


Petratherm's unique "Heat Exchanger within Insulator" (HEWI) model which aims to achieve "low risk, low cost, higher return" is different from other EGS companies.  The HEWI model (refer figure below) contends that significant cost and risk reductions can be achieved by creating the requisite underground heat exchanger within the naturally permeable and porous insulating rock above the granite heat source.

The aim of the HEWI model is to achieve optimal energy exploitation (extraction) through shallow (lower cost) drilling, controlled rock fracture and obtaining appropriate fluid flows and circulation.

Confirming the validity and applicability of the HEWI model will form the next major stage of the development work at Paralana.



Keep up to date with what is happening around Petratherm by subscribing to the alerting service below.