Developing, Testing, and Modeling of an Innovative Thermal Stabilization Method for Alpine Permafrost Protection

Abstract

Permafrost thawing in the Alps and elsewhere is leading to infrastructure failure. Implementation of protective measures is therefore necessary to avoid incidents and damage to both infrastructure and the environment. Existing methods for thermal stabilization of permafrost are not directly applicable to the particular conditions of the Alps. For instance, traditional passive thermal stabilization techniques do not provide rapid and substantial soil stabilization. Meanwhile, active methods present financial constraints and have not yet achieved complete efficiency. Here we present a novel solar-powered thermal stabilization system to effectively protect Alpine permafrost and the most vulnerable infrastructure built on it from the impacts of global warming. To understand how these thermal stabilization methods affect the permafrost, numerical simulations using the SNOWPACK model are performed for the Schilthorn Alpine permafrost site (Switzerland, 2900 m a.s.l.). First, the natural permafrost conditions in the soil are simulated as reference state. Then, thermal stabilization components are included and their effect is quantified and evaluated.To demonstrate the working principle of the thermal stabilization system and to gauge its performance and requirements, a laboratory-scale prototype demonstrator of the system was built and experimental data of the prototype are compared to numerical simulations of a digital twin. The setup includes the components of the thermal stabilization system, which are a cooling pipe for generating a cold barrier layer, as well as temperature, soil moisture, and heat flux sensors for measuring the conditions and processes occurring in the permafrost sample. This data is used to assess the performance and efficiency of the thermal stabilization system. Measurement results indicate that a frozen barrier layer at the level of the pipes can be created and maintained, avoiding heat penetration deeper into the soil and keeping the permafrost sample frozen during the time of the experiment.Findings from the prototype experiment combined with numerical modeling and optimized engineering will enable advanced engineering design and physical process understanding of effective thermal stabilization systems even considering further impact of climate change.