Power obtained by using heat from the Earth's interior. Most geothermal resources are in regions of active volcanism. Hot springs, geysers, pools of boiling mud, and fumaroles are the most easily exploited sources. The ancient Romans used hot springs to heat baths and homes, and similar uses are still found in Iceland, Turkey, and Japan. Geothermal energy's greatest potential lies in the generation of electricity. It was first used to produce electric power in Italy in 1904. Today geothermal power plants are in operation in New Zealand, Japan, Iceland, Mexico, the U.S., and elsewhere.
Learn more about geothermal energy with a free trial on Britannica.com.
Hot Dry Rock Geothermal Energy (HDR) is a type of geothermal power production that uses the very high temperatures (approx 200 Celsius) that can be found in rocks a few kilometers below ground. Electricity is generated by pumping high pressure water down a borehole (injection well) into the heat zone. The water travels through fractures in the rock, capturing the heat of the rock until it is forced out of a second borehole as very hot water, which is converted into electricity using either a steam turbine or a binary power plant system. All of the water, now cooler, is injected back into the ground to heat up again in a closed loop.
HDR wells are expected to have a useful life of 20 to 30 years before the outflow temperature drops about 10 degrees Celsius and the well becomes uneconomic. If left for 50 to 100 years the temperature would probably recover.
HDR and EGS technologies, like hydrothermal geothermal, are expected to be baseload resources which produce power 24 hours a day like a fossil plant. Distinct from hydrothermal (which relies on hot water finding its way to the surface), HDR and EGS are scalable technologies (in that they can be expanded by drilling more wells into deep (hence hot) rock). Good locations are over deep granite covered by a thick (3-5 km) layer of sediments which has kept the heat in .
The recently established Center for Geothermal Energy Excellence at the University of Queensland, has been awarded $18.3 million (AUS) for EGS research, a large portion of which will be used to develop CO2 EGS technologies.
In addition the report has a wealth of data on EGS technology, trial wells and EGS economics.
The largest project in the world is being developed in Australia's Cooper Basin by Geodynamics. The Cooper Basin project has the potential to develop 5,000-10,000 MW. Australia now has 33 firms either exploring for, drilling, or developing EGS projects. Australia's industry has been greatly aided by a national Renewable Portfolio Standard of 25% renewables by 2025, a vibrant Green Energy Credit market, and supportive R&D collaboration between government, academia, and industry.
Germany's 23 cent/kWh US Feed-In Tariff for geothermal energy has led to a surge in geothermal development, despite Germany's relatively poor geothermal resource. The Landau partial EGS project is profitable today under the FIT.
|Project||Type||Country||Size (MW)||Plant Type||Depth (km)||Developer||Status|
|Desert Peak||R&D||United States||11-50||Binary||DOE, Ormat, GeothermEx||Development|
|Paralana (Phase 1)||Commercial||Australia||7-30||Binary||Petratherm||Drilling|
On 30 May 2007, then Australian opposition environmental spokesperson and current Minister for the Environment, Heritage and the Arts Peter Garrett announced that if elected at the 2007 Australian Federal Election, the Australian Labor Party would use taxpayers money to subsidise putting the necessary drilling rigs in place. In an interview, he promised:
- "There are some technical difficulties and challenges there, but those people who are keen on getting Australia into geothermal say we've got this great access to resource and one of the things, interestingly, that's held them back is not having the capacity the put the drilling plants in place. And so what we intend this $50 million to go towards is to provide a one for one dollars. Match $1 from us, $1 from the industry so that they can get these drilling rigs on to site and really get the best sites identified and get the industry going.
The DOE committed $1.6 million towards its EGS R&D project at Desert Peak.
Basel is in a known earthquake zone (see Basel earthquake) and sits atop a historically active fault. Seismicity associated with hydraulic stimulation can be mitigated and controlled through predictive siting and other techniques. The Basel HDR project is currently under review.
WA's Onshore Petroleum, Geothermal Energy and Pipeline Operations Get New OHS Regime.(Geothermal Energy Resources Act 1967)(The Petroleum Pipelines Act 1969)(Occupational Safety and Health Act 1984)
Sep 13, 2010; Key Points: Significant changes to the OHS legislative framework for petroleum, geothermal energy and pipeline operations in...
WA's onshore petroleum, geothermal energy and pipeline operations get new OHS regime.(Western Australia)(occupational health and safety)
Nov 03, 2010; Key Points: Significant changes to the OHS legislative framework for petroleum, geothermal energy and pipeline operations in...