Geothermal power is a natural resource which is under used as a form of energy and is a significant option to generate large amounts of base-load power. It has often been described as a cost effective, reliable, sustainable and environmentally friendly power alternative, but has historically been limited to areas near tectonic plate boundaries. Recent advances in the technology used to harness geothermal power have allowed expansion in the range and size of viable resources, opening the possibilities of geothermal power sources.
Exploration involves finding vast blocks of “hot rocks” with fracture systems that can generate electricity through water being injected, circulated through the fractures and being returned to the surface as steam. Fluids that are drawn from the earth carry a mixture of gases including carbon dioxide, hydrogen sulphide, methane and ammonia. In addition to these, hot water from geothermal sources may hold in solution trace amounts of toxic chemicals such as mercury, arsenic, boron and antimony. The chemicals precipitate as the water cools and the modern practice of injecting cooled geothermal fluids back into the Earth to stimulate production has the additional benefit of reducing this environmental risk.
In Australian geothermal developments, hot water under pressure flows 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 proved. Once the heat has been removed from the geothermal water it is re-injected into the reservoir to be heated and used again.
Plant construction can affect the stability of the land. Subsidence has occurred in New Zealand and Germany and a project in Switzerland was suspended as more then 10 000 seismic events measuring up to 3.4 on the Richter Scale occurred over the first 6 days of water injection.
After months of research on Geothermal Seismic Arrays from Geothermal Projects all over the world, ES&S have developed a world class microseismic monitoring array. With proven experience in microseismic monitoring, and over 30 years of seismic network operation experience, ES&S offer a comprehensive monitoring service – including in-house design, high quality instrumentation, installation, array maintenance, data analysis and result interpretation and reporting. Micro-seismic activity is a vital part of a geothermal reservoir creation and if correctly monitored, can be used to help characterize geothermal, hydrocarbon & CCS reservoirs. This activity can give a real time, low-error indication of what is happening at the point of injection, throughout the production well, injection well and the surrounding region.
If you would like more information on the ES&S Monitoring Service please contact us.
Lund, John W. (June 2007), "Characteristics, Development and utilization of geothermal resources", Geo-Heat Centre Quarterly Bulletin (Klamath Falls, Oregon: Oregon Institute of Technology) 28 (2): 1–9, ISSN 0276-1084, http://geoheat.oit.edu/bulletin/bull28-2/art1.pdf, retrieved 2009-04-16
Waffel, Mark (March 19, 2008), "Buildings Crack Up as Black Forest Town Subsides", Spiegel Online International (Der Spiegel), http://www.spiegel.de/international/zeitgeist/0,1518,541296,00.html, retrieved 2009-02-24
Deichmann, N.; et. al. (2007), Seismicity Induced by Water Injection for Geothermal Reservoir Stimulation 5 km Below the City of Basel, Switzerland, American Geophysical Union
Patel, 2009
