Risk Assessment Strategies for Enhanced Geothermal Systems

  Risk Assessment Strategies for Enhanced Geothermal Systems Urheberrecht: Chen Tao

Engineered Geothermal Systems (EGS) have great potential for large‐scale conversion of geothermal heat into electric energy. Water is injected at high pressure into hot rock at depth of about 3 km - 5km for creating fractures which form an engineered underground heat exchanger. Cold water is then injected which heats up and is produced for driving a steam power plant at the surface. However, engineering of EGS heat exchangers requires a system layout in which the outcome can be predicted only within uncertainty which, at present, is unspecified.

Pilot projects in EGS revealed significant levels of risk with regard to both induced seismicity (Evans et al. 2010) and insufficient flow rates and associated low power production (Gerard et al. 2006). Improving the reliability of the technology as a prerequisite for large‐scale commercialization requires estimating production temperature and flow rate within a specified uncertainty and, based on these results, proposing optimal layout configurations.

The main objective of the research is quantifying the uncertainty of Enhanced Geothermal Systems. It requires developing formal procedures for evaluating the technological risk. Adequate modeling of the relevant processes is crucial for such a reliable risk assessment. The proposed work addresses this problem at the field‐scale.

Reference:

Gerard, A., Genter, A., Kohl, T., Lutz, P., Rose, P., Rummel, F., 2006. The deep EGS (Enhanced Geothermal System) project at Soultz-sous-Forets (Alsace, France), Geothermics 35 (2006), 473 - 483.

Evans, K. F., Zappone, A., Kraft, T., Deichmann, N., Moia, F., 2012. A survey of the induced seismic responses to fluid injection in geothermal and CO2 reservoirs in Europe, Geothermics 41, 30 - 54.