In this book, effective computational methods to facilitate those pivotal simulations using open-source software are introduced and discussed with a special focus on the coupled thermo-mechanical behavior of the rock salt. A cohesive coverage of applying geotechnical modeling to the subsurface storage of hydrogen produced from renewable energy sources is accompanied by specific, reproducible example simulations to provide the reader with direct access to this fascinating and important field. Energy carriers such as natural gas, hydrogen, oil, and even compressed air can be stored in subsurface geological formations such as depleted oil or gas reservoirs, aquifers, and caverns in salt rock. Many challenges have arisen in the design, safety and environmental impact assessment of such systems, not the least of which is that large-scale experimentation is not a feasible option. Therefore, simulation techniques are central to the design and risk assessment of these and similar geotechnical facilities.

This introduction to geothermal modeling deals with flow and heat transport processes in porous and fractured media related to geothermal energy applications. Following background coverage of geothermal resources and utilization in several countries, the basics of continuum mechanics for heat transport processes, as well as numerical methods for solving underlying governing equations are discussed. This examination forms the theoretical basis for five included step-by-step OpenGeoSys exercises, highlighting the most important computational areas within geothermal resource utilization, including heat diffusion, heat advection in porous and fractured media, and heat convection. The book concludes with an outlook on practical follow-up contributions investigating the numerical simulation of shallow and deep geothermal systems.