Q. What is Geothermal Energy?
 A. The Earth is constantly generating naturally occurring energy. This heat is known as geothermal heat, and can be used to produce electricity. Electricity produced from geothermal energy is environmentally friendly and renewable.

Q. What are the three types of geothermal resources?
A.

Q. How is geothermal heat produced?
A. Geothermal heat comes from the slow decay of radioactive elements deep within the earth's core. The heat is transferred or conducted towards shallower rocks near the surface.

Q. Where is geothermal electricity being developed in Australia?
A. There are two main locations:
In South Australia and Tasmania, where deeper granite basement rocks are suitable for EGS style developments and
Near the southern Victorian coastline (and stretching into South Australia), where sedimentary style geothermal resources have been identified by earlier oil and gas drilling.

Q. Has geothermal energy been used commercially in Australia?
A. Yes, there have been two small scale examples in Australia. The small town of Birdsville used geothermal electricity sourced from hot water from the Great Artesian basin until recently. At Portland, the town used a geothermal district heating scheme for about twenty years, using hot water from the Otway Basin resource. Several companies within Australia are now developing both EGS and sedimentary geothermal systems. Most companies expect to develop proof of concept projects before full scale commercial deployment. One example of a forthcoming development is Petratherm which plans to provide power to Beverley uranium mine by 2010, from its flagship project at Paralana in the northern Flinders Ranges.

Q. How is electricity produced from geothermal energy?
A. In Australian geothermal developments, hot water under pressure will flow from a network of production wells into a binary cycle power plant. The energy is transferred into a secondary working fluid with a heat exchanger. The working fluid boils, producing high-pressure vapour that is used to drive the turbines, coupled to a generator. Binary power plants are widely used in the geothermal industry overseas and are well proven.
Once the heat has been removed from the geothermal water, it is re-injected into the reservoir to be heated and used again.

Q. How is EGS different from volcanic and sedimentary geothermal resources?
A. All three make use of naturally occurring heat to produce power. Volcanic and sedimentary resources usually have natural occurring cracks and fractures (reservoir) which allow water to flow into wells and bring hot fluids to the surface. In EGS, developers have to create this reservoir.

Q. How is the geothermal reservoir established in EGS?
A.  EGS developers use a process known as hydraulic stimulation, where water is pumped into wells at high pressure slowly over a period of a few days or weeks. This process opens up existing narrow fractures and joints and man makes the geothermal reservoir.

Q. Will the geothermal heat ever be used up?
A. Geothermal energy is constantly being generated by the earth over geological time. However EGS sites, where water is circulated through the same geothermal reservoir, will find temperatures are reduced over time. To combat this, a project may develop multiple reservoirs which are used on a rotational basis. The dormant reservoir will naturally re-gain temperature and be available for use again.

Q. Is geothermal energy environmentally friendly?
A. Geothermal energy is virtually free of carbon dioxide and other emissions. The equivalent of a 1000 MW geothermal power plant could save 20 million tonnes of CO2 each year (3% of Australia's current greenhouse gas emissions), by replacing a coal fired power plant.

Q.  What are the advantages of geothermal generation over other forms of renewable power?
A. Geothermal power is the only renewable energy source which can provide long-term base load power, 24/7. Other renewable sources such as wind, solar and wave sources rely on particular environmental conditions and therefore cannot be used for base load generation.

Q. Why is geothermal energy being explored in Australia?
A. Australia is amongst the highest emitters of carbon dioxide per capital in the world, due in part to our reliance on coal and gas fired electricity generation. Geothermal generation can provide a much cleaner substitute. In addition, the cost of coal and gas for these fossil-fired generators is rising due to global demand for these fuels. This means that geothermal electricity will become increasingly cost competitive.

Q. How big is the potential market for geothermal generation in Australia?
A. The national Electricity Market in eastern Australia is expected to require at least 5000 MW of new electricity generation capacity over the next decade - a figure that represents one and a half times South Australia's current capacity. Geothermal energy could make a significant contribution to this demand.

Q. Is there support for geothermal initiatives?
A. State and Federal Governments have both been very supportive of the geothermal industry in recognition of the substantial role it may play in Australia's future power generation.