| Title | Development of geothermal technology to address the climate change issue in the densely populated areas of the world |
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| Authors | Baria, R; Baumgärtner, J; Teza, D; Bennett, T; Glass, H; Jupe, A |
| Year | 2016 |
| Conference | European Geothermal Congress |
| Keywords | Unconventional geothermal energy, climate change, Engineered Geothermal Systems (EGS), Hot Dry Rocks (HDR), hydrothermal systems, population density, geothermal resources |
| Abstract | Historically the attention on geothermal development has been predominantly dedicated to high enthalpy areas of the world such as New Zealand, Iceland, Italy and others where the depth to access high temperature zones in volcanic geology is relatively shallow. This gives a significant economic advantage as the drilling cost can be lower and the resource is relatively well defined. On the other hand, the density of population in these specific areas is extremely low which makes the contribution of such development on a world wide scale relatively insignificant compared to the total available geothermal energy resource. It is apparent that the issue of climate change is becoming crucial and bold attempts will have to be made to effectively curb the combustion of hydrocarbons in order to slow down the emission of greenhouse gasses into the atmosphere. Various assessments indicate that climate change is occurring and that a sizeable part of the world will become uninhabitable due to extreme conditions such as desertification or massive flooding. It is anticipated that this would cause a massive migration of people away from the equatorial regions to the northern and southern hemispheres. This migration, estimated to be in terms of tens of millions of people, potentially leads to local depletion of food, commodities and conventional energy resources, as well as possible conflict between nations. A scenario is put forward in this paper, based on experience, which can help to reduce the impact of this phenomenon and provide a glimpse of hope for the future. Research is being carried out in various parts of the world to understand if geothermal energy resource is viable in non-volcanic areas of the world where the majority of the densely populated regions resides (~ 7 billion). A promising approach is to create an Engineered Geothermal System (EGS), whereby hydraulic manipulation is carried out at great depth to emulate a natural heat exchanger where cold injected water is heated up and brought to the surface to provide high temperature heat for commercial application. The European EGS site at Soultz (France) showed that natural, hydraulically conductive faults do exist in the igneous basement at great depth which can be hydraulically manipulated for extracting hot fluid for geothermal application. These faults are linked to the geomechanical properties of the rock mass and tend to be oriented in line with the direction of maximum horizontal stress. A sound knowledge of geomechanics is crucial to understanding the preferential direction of fluid flow and enhancing the properties of these large conductive faults. Successful commercial EGS projects have been established in Germany (Insheim) and in France (Rittershoffen) which are all located in the Rhine Graben (Baumgärtner & Lerch, 2013; Baujard et al., 2015). A similar project, 1200 km away, is being proposed in Cornwall at the Eden Project using the same concept. The geology in Cornwall comprises of fractured granite with large fault structures, which are oriented in line with the direction of the regional maximum horizontal stress, similar to that in Rhine Graben. The feasibility of EGS in Cornwall is a test case which, if successful, proves the potential for a vast resource worldwide using this concept. This would pave the way for developing sustainable geothermal heat in densely populated, non-volcanic regions and to assist in the mitigation of climate change effects. |