Conventional geothermal resources have heat stored in water – also known as geothermal brine – in existing reservoirs. This is in contrast to hot fractured rock geothermal resources, which rely on the successful development of deep engineered reservoirs.
In Australia, Panax is developing geothermal potential through hot sedimentary aquifers (HSA), a variant of conventional geothermal resources. HSAs have heat stored in existing sedimentary reservoirs in regions of high geothermal gradients.
Such geothermal systems are commercially proven and have been successfully operating for more than 25 years – such as in the Imperial Valley in Southern California – well before carbon credits were in place as an incentive. A recent publication by the Australian Bureau of Agriculture and Resource Economics ranked HSA geothermal as the cheapest technology for zero or low carbon power generation in Australia.
The Penola Project
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Panax is currently focusing on the development of the unique Penola Project on the Limestone Coast of South Australia.
The project will produce energy from geothermal water within sedimentary formations of the Otway Basin, which occur at depths of 3,500–4,500 metres (m). The resources have a high heat flow of 170˚ Celsius, and a thick insulating layer overlying the reservoir formation.
The site is a ‘blind’ geothermal source, which means that there are no expressions of geothermal activity such as mud pools, hot springs, or geysers.
The project will involve geothermal water being brought to the surface through production wells as deep as 4.5 kilometres (km) below the surface. At these depths, the hot water is highly pressurised, preventing it from turning into steam. Panax plans to construct a binary cycle power generation plant, which uses a secondary working fluid, usually butane or pentane, instead of water to drive the turbine.
In this style of plant, the geothermal water is passed through a heat exchanger where some of the heat it contains is transferred into the working fluid, which vaporises when heated and expands to drive the turbine. The turbine then drives a generator that produces electricity.
Spudding of the Salamander-1 well, the first deep production well of the project, took place at the end of January 2010, with a depth of 4,025 m reached in mid-March. The well was completed in record time (44 days) at a cost of $15 million, including $7 million contributed by the Federal Government as part of the Geothermal Drilling Program. At the time of writing, Panax had just announced the production of steam following a reservoir test of Salamander-1. During the test, a bottom hole temperature of 156˚ Celsius was recorded at 4,015 m, with approximately 130˚ Celsius recorded at 3,000 m.
Following the success of drilling, a 5.9 MW grid-connected, a commercial demonstration plant would be constructed with plans to be commissioned by the second half of 2011. This would generate enough power to supply power to approximately 4,000 homes.
Once this has been achieved, the Penola Project and the extensive surrounding Limestone Coast geothermal resources could become a provider of hundreds of megawatts of zero emission base load power generating capacity to the nearby national grid.
At a recent Salamander-1 well site visit, Minister for Resources, Energy and Tourism Martin Ferguson said that unless zero emission base load power could come online in the near future, the renewable energy targets for 2020 could not be met, as neither solar nor wind power could meet the supply targets.
Mr Ferguson has also said that Australia’s energy consumption could rise by over 40 per cent between now and 2030, highlighting the need for smart investment in networks and generation over the next decade.
Mr Ferguson’s comments bode well for the future of Panax’s Penola Project, and the future of geothermal as a viable and low emission alternative to conventional forms of power.
Lambertus de Graaf is the Managing Directory and CEO of Panax Geothermal. He was the founding Managing Director of two successful ASX listed resource development companies, Ross Mining N.L. and Geodynamics Limited.
Panax Geothermal is a Brisbane-based geothermal exploration and development company with Australian and international interests in Indonesia, India and Slovakia. Its focus is the exploration and development of geothermal reserves for conversion into bankable geothermal resources, mainly for the development of commercial, zero emission base load power generation.
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