PORT AUGUSTA

Port Augusta is a major power generation hub supplied by the Northern and Playford Power Stations, which have a combined capacity of 780MWe, meeting around 20% of the State’s electricity requirement.

The power stations use cooling water from Spencer Gulf and high-ash coal from Leigh Creek Coalfield, which is expected to be exhausted of reserves within the next 7-8 years. This will provide a seamless entry for renewable, zero-emitting geothermal energy. In addition, the planned expansion of capacity of the Far North Transmission Network relating to major mining expansions, will create opportunities for additional power inputs at this hub. The challenge faced by the advancing geothermal industry in Australia will be to cross the nexus from proof-of-concept to full commercial development. Therefore the commercial drivers at transmission hubs like Port Augusta will have far-reaching benefits for geothermal developments.

Heat-Flow Drilling

Three cored heat-flow holes were drilled in 2009. All recorded values above the target of 90mW/m². Final heat flows calculated were 101mW/m² at Theoden, 96mW/m² at TKHDIA and 94mW/m² at Thorin 1. Theoden is just 400 metres from the Davenport Substation, the distribution node for the Port Augusta hub.

Modeled temperatures at depth for all three sites are well within the range required for geothermal power production.

Results indicate a zone of high heat flow extending 7km north from Davenport Substation, highlighting the potential for a substantial geothermal field to be defined. Furthermore the result from TKDH1A, located 55km north of Port Augusta, represents a potential new geothermal field.

Seismic Survey Completed

As a consequence of the promising heat flow results, Torrens Energy fast-tracked a seismic survey. The seismic line traverses the Torrens Hinge Zone 8km north of the town of Port Augusta. Approximately 22 kilometres of 2D seismic was collected using the Terrex Bird-wagen MARK IV off-road carrier with HEMI 60 vibrator, following existing tracks and roads east of the Stuart Highway.

Key geological architecture was identified – a thick flat-lying insulating sedimentary cover, overlying interpreted heat-producing basement. This demonstrates that a viable EGS geothermal play could exist at 3,500-4,500m depth at this key location.

Significantly the thick sequence of flat-lying sedimentary cover rocks (green) are terminated to the west and east by geological faulting, demonstrating that the high thermal prospectivity is confined to the Company’s landholding in this area.