Flughafen Zürich AG is pursuing innovative approaches to supplying energy to its site and is investigating an underground glacial gully for its suitability as a large-scale heat and cold storage facility. Following initial promising results from a test well, the company is now planning to build a second well to further explore the potential of this natural formation. If successful, this project could make a significant contribution to meeting the heating and cooling needs of the airport terminal.
The exploration of the glacial gully beneath the airport site, filled with groundwater and gravel, has already spanned two years and yielded positive results in several stages. First, the gully was analyzed using seismic surveys to determine its depth, shape, and the structure of its various layers. Subsequent drilling at three different locations confirmed the results of the initial analysis and indicated the gully's potential as a heat and cold storage facility. To test this hypothesis, an initial test well was drilled last fall, which yielded further positive findings.
Guido Hüni, Head of Energy and Decarbonization at Flughafen Zürich AG, expressed confidence in the results so far: "The volumes of water that could be pumped, as well as the water's flow rate, give us further confidence that the channel can serve as a heat and cold storage facility. We can now assume that it is a closed, barely flowing aquifer. Further tests are now needed to determine the extent to which this storage facility can be used." This assessment indicates that the geological formation has the necessary properties for efficient thermal energy storage.
Detailed planning for the location of a second test well is currently underway. Flughafen Zürich AG currently expects construction of this second well to be completed within the next six months. Following this, the two wells will be connected to conduct circulation tests. The results of these tests will allow for concrete conclusions to be drawn about the actual potential of the glacial trough as an energy source and for evaluating the efficiency of such a storage system.
"With this next step, we will test the efficiency of such a storage facility and, if the results are positive, we can ultimately plan the concrete expansion," said Guido Hüni, explaining the project's next steps. If the tests are successful, the flume – possibly in combination with near-surface geothermal probe fields – could cover a significant portion of the annual heating and cooling needs of the buildings and facilities in the airport terminal area. According to Flughafen Zürich AG, the investment costs to date for researching the flume and constructing the test wells amount to approximately eight million Swiss francs, although the final costs will depend on the number and exact locations of the required wells.
The use of underground geological formations to store heat and cold is an innovative approach that is already being tested and implemented to varying degrees in various regions of Europe and around the world. So-called aquifer storage systems utilize natural groundwater deposits in permeable rock layers to store thermal energy. In summer, for example, heat from buildings or industrial processes can be introduced into the groundwater and extracted again for heating in winter. Conversely, cold can be stored in winter and used for cooling in summer. Such systems can contribute to reducing the consumption of conventional energy sources and improving the energy efficiency of buildings and facilities.
The challenges associated with the use of aquifer storage include precise geological exploration of the subsurface, ensuring sufficient water quality and quantity, and avoiding negative impacts on the groundwater ecosystem. The multi-stage investigation of the channel beneath Zurich Airport indicates that these challenges are being carefully addressed. Seismic surveys and subsequent drilling have already provided important information about the nature and hydrological properties of the channel. The successful operation of the first test well reinforces the assumption that its use as a heat and cold storage facility could be technically feasible.
Flughafen Zürich AG's project is significant in that it is a large-scale infrastructure project that could potentially have a significant impact on the energy supply of a major transport hub. The results of further investigations and the planned circulation tests will be crucial in determining whether the glacial trough actually proves to be a sustainable and efficient energy source for the airport. If the project is successful, it could serve as a model for other airports or large properties with similar geological conditions.
Flughafen Zürich AG emphasizes that this project is part of a comprehensive strategy to reduce its own emissions. In addition to researching the use of geothermal storage, the company is committed to a gradual transition to renewable energies, reducing energy consumption in its buildings, and expanding electricity production through photovoltaic systems. The goal is to reduce the company's own greenhouse gas emissions to net zero by 2040. In this context, the use of the glacial trough appears to be a promising building block for reducing dependence on fossil fuels for heating and cooling.
The scientific support of the project and the commitment of Flughafen Zürich AG to make the findings available to research underscore the pioneering nature of this project. It is not only about meeting the company's own energy needs, but also about gaining important knowledge about the construction and development of deep geological formations as energy storage facilities, thus contributing to the development of innovative technologies in the field of renewable energies. The funding of the project by the Swiss Federal Office of Energy (SFOE) indicates the national importance of this research project.
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