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Geothermal Reservoir Processes: Towards the implementation of research into the creation and sustainable use of Enhanced Geothermal Systems (Geotherm 2)

Scope of project

The pressing need to rethink the Swiss Energy Mix following the decision to phase out nuclear power in Switzerland by 2034 lends added importance to accelerating the development of Enhanced Geothermal System (EGS) technology, which is generally regarded as the only way that geothermal energy can make a significant contribution to the electricity supply. The EGS technology is not mature, and a determined effort is needed from industry, academia and the public sector to accelerate its development, so that a firm estimate can be made of its potential by 2020. Two key problems that are recognized obstacles are the difficulty of engineering a heat exchanger that has the appropriate properties within deep, hot low-porosity rock, and the risk of inducing felt seismic events during the development of the heat exchanger. There are, however, other potential problems that have not yet come to light owing to a lack of experience in operating such plants for long periods - such as clogging of pathways through fluid rock interactions. Progress is best promoted by gaining experience through the attempts to build such systems. The GEOTHERM-1 project was conceived to provide scientific support to the Basel EGS project, and the project team believe this collaboration has yielded excellent results. The industry is now planning more EGS pilot projects in Switzerland, yet GEOTHERM-1 has ended in June 2012. A pre-proposal has been submitted to SNF for a national research project (NCCR) on GeoEnergy, which includes EGS technology amongst others, but this is unlikely to begin until 2014. Thus the project team has conceived a new program of research that will bridge the gap. The program has two complementary elements. This project, called GEOTHERM-2, is an application-oriented package of research that is the subject of this proposal. The other package, called COTHERM, is more focused towards basic research on insights to be gained from natural systems and has been submitted to the SNFs SINERGIA program.
GEOTHERM-2 is a proposal for collaboration between a consortium of geoscience, engineering and social-science groups at ETH Zurich, EPF Lausanne and the Paul Scherrer Institut (PSI) with industrial (Axpo, GeoEnergy Suisse) and public stakeholders (Bundesamt für Energie). GEOTHERM-2 consists of six Modules which are designed to
(1) develop and test novel observational tools for the geomechanics of reservoir creation; to
(2) assess and mitigate the risks associated with noticeable induced seismicity; to
(3) assess potential accidental risks leading to health and environmental impacts as well as public perceptions of risks associated with geothermal energy development and develop strategies for communicating the risks;
(4) expand a multi-scale – multi-process modeling code for simulating the process of reservoir generation as well as the longer-term evolution of the reservoir during production, to
(5) investigate the effects of chemical reaction between fluid and rock on long-term permeability evolution and heat extraction from the fractured geothermal reservoir, and to
(6) design a decision-support tool for optimizing the use of geothermal energy in cities, by quantifying all interacting factors including geological and economic parameters, conversion efficiency and temporal heat storage, complementary energy sources and societal acceptance.


Contact

Prof. Dr. Stefan Wiemer, ETHZ
Telephone: +41 44 633 38 57
stefan.wiemer@sed.ethz.ch