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Zürich, Switzerland

Baujard C.,GEOWATT AG | Schoenball M.,Karlsruhe Institute of Technology | Kohl T.,Karlsruhe Institute of Technology | Dorbath L.,EOST
Geothermics | Year: 2014

The occurrence of induced seismicity during reservoir stimulation requires robust real-time monitoring and forecasting methods for risk mitigation. We propose to derive an estimation of Mmax (here defined as the largest single seismic event occurring during or after reservoir stimulation) using hydraulic energy as a proxy to forecast the total induced seismic moment and to model the transient evolution of the seismic moment distribution (based on the Gutenberg-Richter relation). The study is applied to the vast dataset assembled at the European pilot research project at Soultz-sous-Forêts (Alsace, France), where four major hydraulic stimulations were conducted at 5km depth. Although the model could reproduce the transient evolution trend of Mmax for every dataset, detailed results show different agreement with the observations from well to well. This might reveal the importance of mechanical and geological conditions that may show strong local variations in the same EGS. © 2014 Elsevier Ltd. Source


Calcagno P.,Bureau de Recherches Geologiques et Minieres | Baujard C.,GEOWATT AG | Guillou-Frottier L.,Bureau de Recherches Geologiques et Minieres | Dagallier A.,Bureau de Recherches Geologiques et Minieres | Genter A.,GEIE EMC
Geothermics | Year: 2014

The geothermal potential of a deep sedimentary-rock reservoir, in a Tertiary graben, the Limagne d'Allier basin (Massif Central, France), is assessed. The most interesting geothermal target is identified as a thick basal Tertiary sandstone overlying crystalline Paleozoic basement. The total amount of recoverable energy in this clastic aquifer is estimated at over 500PJ (500×1015J) in the modelled area. The most promising zones appear along the north-western edges of the basin, where sediment infill is thickest. The methodology used for estimating geothermal potential starts from geological field data. The first step is to obtain a better understanding of the structure and geometry of the target zone, using various data such as field measurements, and borehole and geophysical data. These data are reinterpreted through the construction of a 3D geological model. Inconsistencies are checked and turned into a coherent 3D interpretation. The second step consists in meshing the geological model into an unstructured 3D finite-element mesh where realistic thermal boundary conditions are applied. The temperature field is computed in a third step. The thermal calculation is achieved by assuming a purely conductive behaviour and through comparison with existing borehole profiles. The computed temperatures fit the measurements in the deepest part of the Limagne d'Allier basin, while the potential role of fluid flow is highlighted in its upper part, either within more permeable formations, or around the boreholes. A fourth, final, step maps the geothermal potential (recoverable energy) in the deepest part of the Tertiary graben, where the total amount of geothermal energy available is calculated. The result of this work provides valuable guidelines for geothermal exploration in the area and our methodology can be replicated elsewhere. © 2014 Elsevier Ltd. Source


Bayer P.,ETH Zurich | Saner D.,ETH Zurich | Bolay S.,ETH Zurich | Rybach L.,GEOWATT AG | Blum P.,Karlsruhe Institute of Technology
Renewable and Sustainable Energy Reviews | Year: 2012

An overview is presented on the last decade of geothermal heating by ground source heat pumps (GSHPs) in Europe. Significant growth rates can be observed and today's total number of GSHP systems is above 1 million, with an estimate of about 1.25 million mainly used for residential space heating in 2011. These systems are counted among renewable energy technologies, though heat pump operation typically consumes electricity and thus only a fraction of the energy produced is actually greenhouse gas (GHG) emission free. Consequently, only in the most mature markets of the Scandinavian countries and in Switzerland, calculated emission savings reach more than 1% compared to standard heatings. However, Sweden shows that more than 35% is possible, with about one third of these systems in Europe concentrated in this country. Our calculations demonstrate the crucial role of country-specific heating practices, substituted heat mix and primary electricity mix for country-specific emission savings. For the nineteen European countries studied in 2008, 3.7 Mio t CO 2 (eq.) are saved in comparison to conventional practice, which means about 0.74% on average. This reveals that many countries are at an early stage with great potential for the future, but even if the markets would be fully saturated, this average would barely climb to about 30%. These numbers, however, take the current conditions as reference, and when extrapolated to the future can be expected to improve by greener electricity production and increased heat pump performance. © 2011 Elsevier Ltd. All rights reserved. Source


Beardsmore G.R.,Hot Dry Rocks PL | Rybach L.,GEOWATT AG | Blackwell D.,Southern Methodist University | Baron C.,Google
Transactions - Geothermal Resources Council | Year: 2010

This paper establishes a Protocol to estimate and map the Theoretical and Technical potential for Engineered (or Enhanced) Geothermal Systems (EGS) in a globally self-consistent manner compatible with current geothermal public Reporting Codes. The Protocol, derived and modified from that designed by the team lead by Professor David Blackwell at Southern Methodist University (Dallas, Texas), is divided into five stages: • Model the temperature, heat flow and available heat of the Earth's crust down to a depth of 10,000 m • Estimate the Theoretical Potential for EGS power in the crust down to a depth of 10,000 m • Estimate the Technical Potential that can be realized with current technology, and considering geographic, ecologic, legal and regulatory restrictions • Define a level of confidence in the estimated Technical Potential at each location, consistent with public Reporting Codes • Present results using common visualization and data architecture The goal of the Protocol is the production of regional estimates and maps of EGS potential that are directly comparable to one another globally. The maps, estimates and source data will be made freely available for public use and presented in common data formats such as the Keyhole Markup Language (KML) for Google Earth. Source


Rybach L.,GEOWATT AG
Transactions - Geothermal Resources Council | Year: 2010

Tunnels drain the rock zones located above them; as a result a considerable amount of warm water flows into the tunnels and subsequently to the portals. On accounts of its temperature this water cannot be released into nearby rivers without previously being cooled down, due to environmental regulation This energy reserve (drained hot water and heated air) can, however, be used at the tunnel portals for various applications. From Switzerland a whole suite of uses can be reported: space heating, greenhouses, balneology and wellness, fish farming (incl. caviar production). Source

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