PhD Thesis "Development and experimental validation of underground sand-based thermal energy storage systems for medium-temperature applications"

leading research institution at the highest international level and to make a positive contribution to the economy and society.

Our Center for Energy located in Vienna invites applications for a PhD Thesis position. At the Center for Energy, we develop sustainable solutions for the energy system of the future, taking into account technological, regulatory and economic requirements. Our portfolio of topics focuses on three key systems: cities and the built environment, public energy supply systems, and industrial energy systems.

The PhD project focuses on the development and experimental validation of underground thermal energy storage systems for medium-temperature applications (80–110°C). Among thermal energy storage (TES) technologies, underground thermal energy storage (UTES) systems are of particular interest due to their high storage capacity, low-footprint, and long-term heat storage potential. However, existing UTES solutions are predominantly water-based, for e.g. pit thermal energy storage (PTES),and face temperature, safety, and land-use limitations. To overcome these challenges, this PhD explores a novel concept of underground solid media thermal energy storage to enable higher operating temperatures, improved land-use efficiency, and reduced environmental impact.

In Cooperation with TU Wien

• You will carry out laboratory-scale tests to examine the thermo-physical behavior of storage media under controlled charging and discharging cycles.
• You will contribute to the design, construction, and operation of an upscaled SMTES prototype (20-foot container scale) to investigate realistic thermal behavior, temperature stratification, and system dynamics.
• You will evaluate the storage envelope and insulation performance (e.g. glass foam aggregate) from a building-physics perspective, focusing on heat losses, moisture migration, and mechanical stability.
• You will support data acquisition and sensor setup for temperature profiling, model calibration and validation.
• You will apply multi-physical numerical modeling to develop 3D coupled thermo-hydraulic-(mechanical) models and perform system-level simulations to analyse heat and moisture transport within the of the SMTES system and assess its performance under different boundary conditions.
• You will use experimental results to validate models and create a digital twin for real-time operational optimisation.
• Based on your findings, you will establish a design and optimisation framework, including dimensioning and layout principles and correlations between material properties, geometry and operational parameters.
• You will conduct technical performance and environmental analyses, including energy density, thermal efficiency, response time and materials reuse aspects in cooperation with project partners.
• Last but not least, you will evaluate the storage concept and integrate validated models into system-level optimisation, such as coupling with heat pumps or district heating networks.
• You will engage in scientific planning, will publish your findings in international journals and present them at conferences.

Your qualifications as an Ingenious Partner:

• Completed master’s studies or close to completion in the field of Thermal Engineering, Sustainable Energy Systems, Mechanical Engineering, Geotechnical Engineering, Technical Physics or a related technical field
• Good skills in modelling and simulation (Modelica/Dymola, COMSOL Multiphysics )
• Very good understanding of thermal energy storage and heat transfer processes
• First experience in data acquisition and sensor-based-measurements would be a plus
• Good competence in experimental work (design, evaluation)
• High commitment and ability to work individually as well as in a multi-disciplinary-team environment as well
• Strong interest in experimental work and willingness to collaborate with industrial and scientific partners
• Interest in reading and writing scientific publications and enjoy application-oriented research questions from industry
• Very good command of English (spoken and written)

Details:

• Duration of the PhD project: 3 years
• Start date: ideally 01.04.2026 (or even earlier)
• To obtain the PhD degree, you will have to enroll to TU Wien, our academic partner institution. Throughout your PhD, you will be supervised by an academic supervisor from TU Wien, Institute of Fluid Mechanics and Heat Transfer as well by a supervisor and advisor at AIT.

What to expect:

• EUR 2.786,10 gross per month (14 times / year), for 30 h / week.
• Access to state-of-the-art infrastructure on site at AIT
• In addition to numerous events, seminars, networking opportunities and additional company benefits, you will be part of our AIT PhD community with around 150 international students.
• Knowledge exchange with and complementary research input and support for experimental and modelling activities from our collaborating partners: KTH Royal Institute of Technology (Sweden) and University of Stavanger (Norway)

At AIT diversity and inclusion are of great importance. This is why we strive to inspire women to join our teams in the field of technology. We welcome applications from women, who will be given preference in case of equal qualifications after taking into account all relevant facts and circumstances of all applications.

Please submit your documents including your CV, cover letter (ideally one page, including a brief introduction of yourself, an explanation how your previous studies and experience have prepared you for this PhD position, and a motivation why you are interested in this specific position) and your certificates (Transcript of records) online.