Rescue Permafrost
PROJECT "RESCUE PERMAFROST"
Why is it Important to Preserve the Permafrost at Tofana?
Climate change poses a significant threat to various mountain ecosystems. One example is the melting of permafrost, a layer of permanently frozen ground, which can lead to several negative consequences, including soil instability and damage to infrastructure. However, technological innovation can play an effective role in conserving these delicate mountain ecosystems. The upper station of the Pian Ra Valles – Ra Valles – Bus Tofana chairlift has been chosen as a testing ground to demonstrate the effectiveness of this solution, providing a concrete example of how human ingenuity and technological innovation can help mitigate the effects of climate change on permafrost in alpine regions. The main innovation of this project lies in its ability to prevent or slow down the melting process of permafrost caused by the spread of heat from surrounding masses.
INTRODUCTION AND PROJECT CONCEPT
A process is described for cooling the layer of permafrost present in the subsurface of the Pian Ra Valles – Ra Valles – Bus Tofana chairlift’s motor station. This process aims to ensure its maintenance and consolidation. The cooling is achieved through a geothermal system, combined with a
heat pump powered by electricity generated from a photovoltaic system.
The dissipated heat is used for heating residential or technical spaces. To prevent/slow down the thawing of permafrost caused by the heat diffusion from the surrounding masses, as per the aforementioned second law of thermodynamics, the design solution lies in the reverse process, namely one that transfers heat from “lower temperature zones” to “higher temperature zones”. This process doesn’t occur spontaneously and requires the assistance of a refrigeration cycle.
THE PARADIGM REVERSAL
The work required to power the refrigeration cycle is drawn from the external environment, specifically from electrical energy generated by photovoltaic panels, which powers the
compressor (mechanical energy), reversing the paradigm. In this way, the system will exclusively utilize renewable energy sources, and the environmental impact wil be negligible.
Dott. Ing. Mario Vascellari TOFANA SRL – Cortina d’Ampezzo (BL)
PERMAFROST, WHAT IS IT?
PERMAFROST IN THE ALPS
Permafrost is frozen ground characterized by sub-zero temperatures throughout the entire year. The subsurface layer between the ground surface and the permafrost roof is the active layer or thaw zone, which thaws in summer and freezes in winter. Below the permafrost roof, the ground maintains negative temperatures all year round.
The degradation of permafrost causes slope stability issues, increasing the risk of landslides,
especially in populated areas and high-altitude infrastructures, as in the present case.
THE OPERATION OF THE SKI LIFT SYSTEM, THE ENCOUNTERED ISSUE and THE VARIOUS HYPOTHESIZED SOLUTIONS
The chairlift “Pian Ra Valles – Ra Valles – Tofana Bus” falls under the category of “automatic grip“
lift systems. Even during the design and construction phases, it was known that beneath the upper station, there was a layer of frozen ground, called permafrost.
To mitigate the effects of this phenomenon, for the first time, emerged the idea of an active thermodynamic approach (cooling the permafrost and subsequently consolidating it). The implemented intervention aims to counteract the thawing phenomenon and ensure that the surrounding and underlying ground of the upper station does not exceed a temperature of 0°C, thereby maintaining the ice fraction within the permafrost in a solid state.
THE TECHNICAL SOLUTION and THE REFRIGERATION CYCLE
The system aims to stabilize the subsoil through a vertical geothermal installation combined with a chiller unit powered by electricity generated from a photovoltaic system.
An air-to-water electric chiller is installed on the ground floor of the service building of the chairlift. Technically, the system extracts heat from the ground and transfers it to the air via geothermal probes and the chiller unit.
THE PHOTOVOLTAIC SYSTEM
Photovoltaic panels convert the energy of photons from sunlight into electricity.
The electrical energy consumed by the refrigeration unit and circulation pumps is produced on-site using a photovoltaic system with a capacity of 16.5 kWp.
CORE DRILLING AND GEOTHERMAL PROBES
Described is a geotechnical survey conducted in 2019 at the Bus di Tofana location, to support the
construction of a new chairlift and to highlight the presence of permafrost. The majority of the material overlying the rock substrate was found to be frozen.
Subsequently, for the installation of the geothermal probes essential for the refrigeration
cycle, core drilling was carried out using a down-the-hole hammer and casing pipes. Thermometric probes are used to measure temperatures in the layer beneath the ground surface and, of course, within the permafrost.
At geothermal probe No. S4, a new continuous coring was performed to recover material
and subject it to weighing before and after thawing. This was done to establish algorithms
for the implementation of the refrigeration cycle based on the ice content.
Dott.Geol. Stefano Valle GEOLAND Srl Bolzano (BZ)
CONSTRUCTION WORKS and MACHINERY POSITIONING AND ADJUSTMENTS
The installation of the PEAD connecting pipes for the geothermal probes took place within an excavation, while the refrigeration plant was set up in the adjacent room to the existing emergency generator.
The work commenced on June 8, 2023, and was completed with commissioning of the system on July 26, 2023
PRELIMINARY DYNAMIC ANALYSIS OF THE IMPACT OF THE GEOTHERMAL SYSTEM ON THE PERMAFROST SUBSTRATE
Following the analysis of input data, such as soil characteristics and local climate conditions, preliminary simulations were conducted to assess the thermal response of the soil to ambient temperature fluctuations, particularly in the zone with permafrost presence.
Preliminary results demonstrated that the geothermal probe system can have a positive influence on the thermal conditions of the soil beneath the upper station of the lift system, contributing to maintaining permafrost in the area of interest and its immediate vicinity below 0 °C.
In conclusion, the project represents a promising solution t o preserve permafrost in mountainous areas.
ANALYSIS OF ENERGY EFFICIENCY OVER TIME
Capturing the energy of the sun to preserve the permafrost: this is the ambitious goal that is aimed to be achieved. The challenge to overcome is to optimize the entire system, consuming the least amount of precious electrical energy to achieve the maximum benefit for the permafrost
An example of the operation of a refrigeration machine similar to the one that will be installed in this system is shown in the figure, where the relationship between obtained cooling power and absorbed electrical power over time is depicted for three different ambient air temperatures. The aim will be to favor operation when the ambient air is cooler, accumulating the cooling energy produced in the ground.
THE SNOW AND WEATHER STATION OF RA VALLES
The Ra Valles Nivometeorological Station (2615 m) is part of the regional snow cover monitoring network managed by ARPA Veneto- UNVSV-Arabba Avalanche Center.
The data collected by the meteorological station are essential for the analyses conducted by the Department of Technical and Industrial System Management at the University of Padua and the Environmental Technical Physics Group of the Faculty of Engineering at the Free University of Bolzano. These data serve both historical values that have been used to establish models and future values that, as variables of the model, will enable the model to generate actual rather than simulated results.
MONITORING OF MOVEMENTS OF THE FOUNDATION PLATFORM OF THE UPPER STATION OF THE CHAIRLIFT
To carry out this monitoring, the decision was made to use the Global Navigation Satellite System (GNSS) and install a Leica GM10 GPS data processing module that regularly transmits the 3D coordinates (latitude, longitude, and elevation) with an antenna mounted on the infrastructure of the monitored Pian Ra Valles – Ra Valles – Bus Tofana chairlift station.
The collected data over time will help understand if there are any structural displacements and their potential magnitude. This system achieves post-processing accuracy of 3 mm horizontally and 4 mm vertically, providing an exceptionally high level of measurement precision to assess the stability of the chairlift station’s foundation following the operation of the cooling cycle.
THE APPLICATION OF RENEWABLE ENERGY REGULATIONS TO THE PLANT, ENVIRONMENTAL, LANDSCAPE, AND SYSTEM ASPECTS
The area in which the facility is located, due to its extraordinary natural characteristics, is subject to particularly impactful protection measures. The specific implementation methods of the facility have allowed it to fall within the scope of the new simplification regulations for authorization procedures related to the construction of small renewable energy facilities.
The implemented technical solution indeed leverages known components but coordinates them innovatively to enhance the stability of the facility.
Harnessing solar energy to preserve permafrost is the ambitious goal being pursued. By doing so, the facility will solely utilize renewable energy, and its environmental impact will be virtually negligible.
partners and promoters of the project
