Friday, 31 August 2012

Geothermal Power Is HOT!

From ERIC SHACKLE, in Sydney, Australia.

If you drill a deep well in several areas of Australia, and then pour water down it, the water turns to steam, and returns in a jet fierce enough to drive a turbine to generate electrical power. It’s an exciting concept called geothermal power.

It’s in its infancy in Australia, but several companies are actively developing it. There are known and potential locations near the centre of the country that have been shown to contain hot granites at depth which hold good potential for development. Exploratory geothermal wells have been drilled to test for the presence of high temperature geothermal reservoir rocks and such hot granites were detected. As a result, projects will eventuate in the coming years and more exploration is expected to find new locations. 

For the British company specialising in the development of geothermal resources, see Geothermal Engineering Ltd.

At the core of the Earth, thermal energy is created by radioactive decay and temperatures may reach over 5000 degrees Celsius (9,000 degrees Fahrenheit). Heat conducts from the core to surrounding cooler rock. The high temperature and pressure cause some rock to melt, creating magma convection upward since it is lighter than the solid rock. The magma heats rock and water in the crust, sometimes up to 370 degrees Celsius (700 degrees Fahrenheit).

Exploratory geothermal wells have been drilled to test for the presence of high temperature geothermal reservoir rocks and such hot granites were detected.

As a result, projects will eventuate in the coming years and more exploration is expected to find new locations. From hot springs, geothermal energy has been used for bathing since Paleolithic times and for space heating since ancient Roman times, but it is now better known for electricity generation.

Worldwide, about 10,715 megawatts (MW) of geothermal power is online in 24 countries. An additional 28 gigawatts of direct geothermal heating capacity is installed for district heating, space heating, spas, industrial processes, desalination and agricultural applications.

Geothermal power is cost effective, reliable, sustainable, and environmentally friendly, but has historically been limited to areas near tectonic plate boundaries. Recent technological advances have dramatically expanded the range and size of viable resources, especially for applications such as home heating, opening a potential for widespread exploitation.

Geothermal wells release greenhouse gases trapped deep within the earth, but these emissions are much lower per energy unit than those of fossil fuels.

As a result, geothermal power has the potential to help mitigate global warming if widely deployed in place of fossil fuels. The Earth's geothermal resources are theoretically more than adequate to supply humanity's energy needs, but only a very small fraction may be profitably exploited.

Drilling and exploration for deep resources is very expensive. Forecasts for the future of geothermal power depend on assumptions about technology, energy prices, subsidies, and interest rates. Polls show that customers would be willing to pay a little more for a renewable energy source like geothermal. 

But as a result of government assisted research and industry experience, the cost of generating geothermal power has decreased by 25% over the past two decades.

In 2001, geothermal energy cost between two and ten cents per kilowatt. The 30 MW Paralana project is located adjacent to the Beverley Uranium Mine. It is an enhanced geothermal system (EGS) project, based on Petratherm’s "heat exchanger within insulator" model. 

The 25 MW Cooper Basin demonstration project will demonstrate the potential of hot-rock geothermal energy for zero-emission, base-load power. 

The project is owned by Geodynamics and will be the world’s first multi-well hot fractured rock power project. Geodynamics has assessed its resource as holding geothermal energy sufficient to support several thousand megawatts of electricity generating capacity. The Jurien-Woodada project, owned by New World Energy Limited, is the most advanced geothermal play in Western Australia for electricity production.

The project is adjacent to transmission infrastructure and large resource-driven energy markets in the mid-west region. The project area has the potential to contain both hot sedimentary aquifer and EGS styles and is being assessed for delivery of electricity into Western Australia's South West Interconnected System. [ The Penola Project is part of Panax’s Limestone Coast Project and is the largest of only three known Measured Geothermal Resources in Australia. An independent assessment has estimated the geothermal resource potential at 11,000 petajoules.

The Penola Project has an extensive database with 28 petroleum wells. The deepest petroleum exploration well is approximately 4,000 metres and intersects more than 1,000 metres of the target reservoir, the Pretty Hill Sandstone.

Panax’s Salamander-1 well, drilled in 2010 is the first deep geothermal well drilled in the Otway Basin. It was completed in record time and is the first to demonstrate conventional geothermal technology in Australia. First steam was produced and the well-testing program was also completed on the project in 2010. The Salamander-1 well met its primary objectives.

At 4,000 metres projected geothermal temperatures were exceeded by more than 10oC and target reservoir rocks met the requirements for the development of a geothermal demonstration plant. An in-house pre-feasibility study found the project has the potential to generate power at $83 per megawatt hour, which is cheaper than wind power.

Complication with the well were found during well-testing. Reservoir engineers have been engaged to examine the well and carry out remediation works. Panax is pioneering conventional geothermal technology in Australia with its Salamander-1 well and is securing funding from the Australian Federal Government to progress the

Penola Project. Video:

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