And across the Tasman, the New Zealand Government’s GNS Science believes abandoned oil and gas wells could potentially produce enough geothermal energy to power a small city.
Perth-based Green Rock late last year acquired an interest in a Hungarian joint venture seeking to establish the first geothermal power plant in Eastern Europe by utilising energy from existing shut-in or disused petroleum wells.
The partners – operator Hungarian oil and gas company MOL (36%), Green Rock (32%), and Icelandic geothermal consulting company Enex (32%) – have started their initial project in the southwest of the country and the first two wells, Ortaháza-3 and Ortaháza-5, are scheduled to be tested for hot water production rates over the next six months.
The tests are designed to gather detailed data on the wells and water-bearing zones for the possible subsequent construction and operation of a geothermal power plant.
Green Rock, which is contributing about $A2.1 million to this program, says the aim of the project is to install and commission a 2-5MW geothermal power plant during 2008.
Any development will also see the geothermal water, after passing through the power plant, providing heat for industrial purposes and a greenhouse agricultural operation.
Green Rock’s move into Hungary, which has a growing demand for renewable energy, is part of its plan to expand into the international geothermal sector as it seeks to become a major developer of such projects.
Green Rock also wholly owns the South Australian Olympic Dam geothermal energy project, comprising 2899 square kilometres of geothermal tenements around BHP Billiton’s Olympic Dam copper mine. Green Rock hopes to develop a 500MW geothermal power plant with capacity to supply electricity to the mine and the surrounding area.
New Zealand
Meanwhile, GNS Science believes abandoned oil and gas wells could produce enough geothermal energy to power a city the size of Christchurch (population 350,000).
Temperatures at the bottom of about half of New Zealand’s 360 abandoned onshore oil and gas wells are hot enough to produce geothermal power, while the remainder have enough heat for direct industrial applications and geothermal heat pumps.
Estimated temperatures at the bottom of New Zealand’s abandoned wells range from 20C in the shallowest to nearly 180C in the deepest wells, some of which are nearly 5km deep.
In Taranaki, there are nearly 50 abandoned onshore wells with bottom temperatures higher than 80C that can potentially be used for binary cycle geothermal power production.
In addition, there are dozens of lower temperature abandoned oil and gas wells where heat can be harnessed directly for uses such as drying of farm produce, milk pasteurisation, greenhouses, and heating houses and offices using geothermal heat pumps.
Presently, only one New Zealand abandoned oil well is being used commercially to produce geothermal energy. The Bonithon-1 well in New Plymouth, drilled in 1908, is a source of hot thermal water for the Taranaki Mineral Pools.
Momentum for harnessing this unconventional energy source has been growing steadily in the United States, where scientists estimate the geothermal energy potentially available from disused oil and gas wells in seven southern states to be at least 5000MW of electricity.
Despite some ongoing problems, Australian geothermal explorers remain confident that large quantities of energy can be produced from below the surface of the Southern Hemisphere continent. Some believe Australian geothermal hot rock resources are among the best in the world outside volcanic regions.
Hot fractured rock projects, which aim to artificially create underground heat exchangers, have a relatively high profile in the Australian energy industry, though none have yet succeeded in producing commercial electricity.
However, conventional geothermal power generation is used successfully in several countries around the world.
There are currently about 250 conventional geothermal electricity plants worldwide producing a total output of 8900MW. Geothermal energy is Iceland’s second-largest source of power, while it provides about 7% of New Zealand’s electricity needs.
