Hot rocks in Australia - National overview

Abstract

Hot Rocks have potential to fuel competitive, emission free and renewable electricity for centuries to come. This potential is stimulating Enhanced (Engineered) Geothermal Systems projects worldwide, calling upon integrated expertise from the petroleum, minerals and power industries. Converting just 1% of Australia?s estimated Hot Rock crustal energy to electricity, from temperatures above 150°C and depths below 5 km (190 million PJ) would supply 26,000 years of Australia?s primary power use, and that neither takes into account the renewable characteristics of hot rocks, nor resources below 5,000m. Factors that distinguish Australian Hot Rock resources are: (1) Very radioactive granites are abundant, as in South Australia where the mean heat flow is 92 µWm-2 compared to a global continental average of 51µWm-2 ; and (2) Australia is converging with Indonesia on a plate scale - giving rise to common, naturally occurring sub-horizontally fractured basement rocks that are susceptible to hydraulic fracture stimulation. Australia?s geothermal projects are focused on both Hot Rocks to develop Enhanced (Engineered) Geothermal Systems and associated Hot Sedimentary Aquifer plays to fuel binary power plants. In addition to meeting demand for base load power, mining, desalinisation and drying processes are also markets for geothermal energy.In the term January 2000 through December 2008, companies have applied for 385 licence areas (covering 359,723 km2) to progress proof-of-concept amagmatic Hot Rock and Hot Sedimentary Aquifer projects in Australia. In the term 2002 through 2008, more than Aus$325 million (US$228 million) has been spent on studies, geophysical surveys, drilling, reservoir stimulation and flow tests that comprise the work programs required to sustain tenure in geothermal licences areas. In the term 2002-2013, investment for Australian proof-of-concept geothermal projects is expected to exceed Aus$1,523 million (US$1,066 million). This rapidly rising level of investment is driving sector-wide cooperation to support high priority and complementary research that can speed the pace and lower the cost of commercialising Australia?s vast Hot Rock (HR) and Hot Sedimentary Aquifer (HSA) geothermal plays. That cooperation is underpinned with more than Aus$110 million (US$77 million) in Australian Federal and State government grants to meet up to half of the cost of the private sector?s field efforts. This includes Aus$60 million (US$42 million) available to support new deep drilling for the proof-of-concept HR and HSA projects, but excludes Aus$507 million (US$355 million) for all forms of meritorious, commercial-scale demonstration of renewable energy technologies, including geothermal projects. This paper summarises: (1) proof-of-concept amagmatic HR and HSA geothermal projects co-funded by investors and governments in Australia; (2) policies, programs and alliances put in place to support the development of geothermal plays; (3) research priorities and studies undertaken in support of geothermal projects and (4) emerging protocols to build trust with stakeholders, including a reporting code for geothermal resource and reserve estimates and best practice procedures for the management of potential risks associated with induced seismicity.