Hot Rocks Downunder - Geothermal Plays in Australia*

Abstract

Australia's hot rock and hydrothermal resources have the potential to fuel competitively-priced, emission-free, renewable baseload power for centuries to come. This potential and the risks posed by climate change are stimulating geothermal energy exploration projects in Australia.

Extracting just 1 percent of the geothermal between the depth to 150°C and 5,000m would yield ~190 million PJ or about 26,000 times Australia's primary power usage in 2005, and that does not take into account the renewable characteristics of hot rock Enhanced Geothermal Systems (EGS) or the resource below 5,000m.

Twenty-nine companies have joined the hunt for geothermal energy resources in 204 licence application areas covering approximately 187,000 km2 in Australia. Most exploration efforts are currently focused on hot rocks (EGS) to fuel binary power plants. Roughly 80 percent of these projects are located in South Australia.

A considerable investment (US$170+ million) is required to prove a hot rock play, and demonstrate the reliability, scalability, and efficiency of EGS power production. The proof-of-concept phase entails the drilling of at least two deep (>3,500m) hot holes (one producer and one injector) as well as fracture stimulation, geo-fluid flow and reinjection and heat exchange to generate electricity. Up-scaling for compelling demonstration projects entails additional wells and smooth operations from a binary geothermal power plant.

Play and portfolio assessment methods currently used to manage the uncertainties in petroleum exploration can usefully be adapted to underpin decision-making by companies and governments seeking to push and pull hot rock energy supplies into markets.

The presentation will cover the geology, challenges, and promising future for hot-rock geothermal energy projects in Australia.