Hi enviro, from what i can gather cost would be cheaper than nuclear power.   if, possibly there was an accident there would be no fall out, except for building material....
A good site to have a squizz would be      eere.energy.gov/      thats the U.S. dept of energy.
go to programs,,, GEOTHERMAL TECHNOLOGIES,,, and that will give you an idea of the working concept

Why should state energy agencies support the development of geothermal resources?
State energy agencies — regulatory agencies, energy offices, geological surveys, and public service commissions — in the 19 GPW states (see table below) were asked to select the top three most important issues regarding geothermal development in their states.

The following are the results of this informal survey. Issues are listed in order of priority, from the most important to the less important.

1 New direct and indirect jobs created

2 Reduced consumption of fossil fuels and their production of greenhouse gas emissions

3 Displaced emission to the atmosphere of carbon dioxide, sulfur dioxide, nitrogen oxides, and particulate matter

4 Expanded tax base resulting in more tax dollars
Reduced energy costs in rural areas; in urban areas

5 Revenue from the sale of heat, electricity, or other products
Reduced local atmospheric pollution
Expanded rural economies

6 Clean, low risk, lost cost source of energy
Increased energy self-sufficiency and energy security 

http://www.geothermal-biz.com/state_energy.htm

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Wind Power isn't as reliable due to changing wind patterns.

You are here: EnergyKidz home > Renewable energy > GeothermalGeothermal
Geothermal energy is energy from the heat of the earth. It has been used for thousands of years in some countries for hot water, cooking and heating. It can also generate electricity using steam produced from heat found beneath the surface of the earth. It is not common in Australia, but is used in some parts of New Zealand and through Europe.

When water flows over hot rocks, hot water and steam are created and escape to the earth's surface. Bubbling mud pools, hot springs and geysers are examples of geothermal energy. Volcanoes are very violent examples of this type of energy.
The hot water and steam created underground can be used to create electricity (by turning turbines) to heat homes and other buildings. The steam is collected, and used to power a generator, in the same way it is used in a coal fired power station.
The Maoris of New Zealand use hot rocks to cook food in the ground. Around the world people also swim in warm natural springs to help soothe body aches and pains.
Another form of geothermal energy is called "hot rock". This is where water is pumped below the surface to areas of hot rock. The water then turns to steam, and is pumped back to the surface to drive a turbo-generator.
Australia does not currently produce electricity from geothermal energy. However, tests are being carried out on a "hot rock" power station.


Advantages of using geothermal energy

· It's free once built.
· It is renewable (ie. it won't run out).
· It does not take up very much land, and does not spoil the landscape.

Disadvantages of using geothermal energy

· Some geothermal sites may 'run out of steam'.
· Hazardous minerals - which are difficult to dispose of - may be produced.
Geothermal energy sites can be difficult to find

http://www.energy.com.au/energy/ea.nsf/Content/Kids+Geothermal

Geothermal

About This Technology   Geothermal energy is continuously created beneath the Earth's surface from the extreme heat contained in liquid rock (called magma) within the Earth's core. When this heat naturally creates hot water or steam, it can be piped to the surface and then used to turn a steam turbine to generate electricity. Geothermal energy can also be obtained by piping water underground to extract heat from hot, dry rocks. Heat is then returned to the surface to turn a steam turbine and generate electricity.

Reserves   Although geothermal energy exists everywhere in the United States, it is not easy to extract unless it is close to the surface. Some areas of the United States with the greatest potential for generating electricity from geothermal energy include portions of Nevada, California, Oregon, Idaho, Utah, Washington, Alaska, Montana, Arizona, and Hawaii. In 2003, geothermal capacity was 2,300 MW. Currently identified resources could provide more than 20,000 MW of power in the United States, and undiscovered resources might provide five times that amount.3

Environmental Impacts

Air Emissions   Emissions associated with generating electricity from geothermal technologies are negligible because no fuels are combusted.

Water Resource Use   Geothermal power plants usually re-inject the hot water that they remove from the ground back into wells. However, a small amount of water used by geothermal plants in the process of creating electricity may evaporate and therefore not be returned to the ground. Also, for those geothermal plants that rely on hot, dry rocks for energy, water from local resources is needed to extract the energy from the dry rocks.

Water Discharges   Geothermal power plants can possibly cause groundwater contamination when drilling wells and extracting hot water or steam. However, this type of contamination can be prevented with proper management techniques. In addition, geothermal power plants often re-inject used water back into the ground (through separate wells) instead of discharging the used water into surface waters. This prevents underground minerals or pollutants from being introduced into surface waters.

Solid Waste Generation   Geothermal technologies do not produce a substantial amount of solid waste while creating electricity.



http://www.epa.gov/cleanrgy/renew.htm
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With Australia in a water crises this does make it hard to recommend today but, if our water crisis is solved then Hot Rock GeoThermal Energy will be our best alternative.

Apparently they are looking at the Hunter Valley for NSW. Probably where existing coal power stations are as there is plenty of water in Lake Macquarie.