Speaker
Michele Pipan
(Università degli Studi di Trieste, Italy)
Description
Advanced geophysical imaging and characterization techniques coupled with enhanced heat extraction methods can support the extensive utilization of geothermal resources worldwide. The primary objectives of the new technologies are the reduction of costs and risks associated to the exploitation of deep high enthalpy resources and the optimization of heat extraction from geothermal reservoirs.
The heat stored in the interior of the Earth is a ubiquitous, clean, cheap and renewable source of energy available for direct use and for the production of electricity. The latter started at the beginning of the twentieth century (1904, Larderello, Italy) and was limited to areas characterized by anomalous geothermal gradient, i.e. the boundaries of tectonic plate, until recently. Two main routes can be presently considered to extend the use of geothermal energy and make such renewable resource follow an exponential development trend, compared to the linear one that it has been experiencing in the last decades: Enhanced Geothermal Systems (EGS, also known as Hot Dry Rock) and binary plants. EGS technology has been tested in demonstration projects but still lacks extensive application while binary plants are now producing electricity at several locations worldwide (e.g. Hilo, Hawaii and Mammoth Lakes, California).
A necessary condition for the expansion of the geothermal sector based on advanced reservoir management and plant technologies is the improvement of the techniques employed in the initial exploratory phase for the identification and characterization of resources. Geothermal energy costs are among the lowest in the sector of renewable sources (around USD/kWh 0.12, estimated levelized costs for plants entering service in 2016, by U.S. Department of Energy) and it is therefore extremely competitive when the geothermal resources have been successfully identified and the characterization of the reservoir allows a sustainable heat extraction plan. Geophysical methods based on the integration of seismic and EM (electromagnetic) techniques presently offer unique opportunities for effective exploration and monitoring of geothermal resources. In particular, 3-D depth seismic imaging and joint inversion of seismic and EM data allow understanding of complex subsurface conditions and substantial reduction of associated capital risks in the exploitation of deep resources. Passive (micro-tremor) and interferometric methods further allow cost effective monitoring of deep reservoirs and optimization of heat extraction.
Author
Michele Pipan
(Università degli Studi di Trieste, Italy)
