Utrecht University, Faculty of Geosciences, Department of Earth Sciences

Utrecht University’s Faculty of Geosciences studies the Earth: from the Earth’s core to its surface, including man’s spatial and material utilisation of the Earth – always with a focus on sustainability and innovation. With a population of 3,400 students (BSc and MSc) and 720 staff, the Faculty is a strong and challenging organisation. The Faculty is organised in four Departments: Earth Sciences, Physical Geography, Sustainable Development, and Human Geography & Spatial Planning.

The Department of Earth Sciences conducts teaching and research across the full range of the solid Earth and environmental Earth sciences, with activities in almost all areas of geology, geochemistry, geophysics, biogeology and hydrogeology. Our key research themes are Earth & Planetary Processes, Sustainable Use of the Subsurface, Planetary Health & Environment, and Climate & Life.The department hosts a highly international tenured staff of over 50 scientists and more than 110 PhD students and postdoctoral researchers. We house or have access to a wide variety of world-class laboratories, among which are UU’s Electron Microscopy Centre, the Geolab, and the Earth Simulation Lab. We also have excellent High- Performance Computing facilities.

About Utrecht
Utrecht is the fourth largest city in the Netherlands with a population of nearly 360,000 and forms a hub in the middle of the country. Its historical city centre and its modern central station can easily be reached from our campus in Utrecht Science Park by public transport or by a 15-minute bicycle ride. Utrecht boasts beautiful canals with extraordinary wharf cellars housing cafés and terraces by the water, as well as a broad variety of shops and boutiques.

Homepage: https://www.uu.nl/geo/aw

The Department of Earth Sciences is looking for a highly motivated candidate for a PhD position at its High Pressure and Temperature Laboratory, run by the Experimental Rock Deformation group.

Your job
High-temperature thermal energy storage is playing an increasingly vital role in the transition to a low-carbon future. One of the most promising opportunities is the repurposing of abandoned and end-of-life coal mines as large-scale underground thermal batteries. Coupled with solar energy, these systems can deliver low-carbon, high-temperature district heating in winter.

Sustainable mine water thermal energy storage requires a solid understanding of the complicated water flow dynamics in mined geological formations, which differ fundamentally from those in natural porous media. Underground mine systems consists of mine goaf and underground workings, surrounded by saturated porous rocks. Water flows through these mined voids much faster than through aquifers, offering a significant advantage over conventional aquifer thermal energy storage. However, this also increases the risk of premature thermal breakthrough, reduced thermal longevity of solar energy-charged systems, and heat loss to surrounding rocks. To ensure reliable and efficient thermal energy storage, it is essential to understand how heat and water are stored and transported through fractured, porous, and geomechanically altered rocks under in-situ temperature and pressure conditions. This PhD project is part of the EU RFCS-funded GeoSolar project, which aims to advance high-temperature thermal energy storage technologies and support the just transition of Europe’s end-of-life coal mines. The project will involve close collaboration with mining companies, geothermal technology providers, and district heating network operators.

Within this PhD project, you will:

• perform experimental characterisation of mine goaf rocks from selected end-of-life coal mines, focusing on their thermal, hydrological and mechanical properties under in-situ pressure and temperature conditions;
• develop and apply fully-coupled thermo-hydro-mechanical models to simulate mine water flow and heat storage dynamics within underground mine systems; and
• evaluate the potential for seasonal heat storage and recovery, contributing to the optimisation of operational performance and energy efficiency in mine water thermal energy storage systems.

Throughout the project, you will regularly interact with the other consortium partners and present your findings to the broader scientific and industrial community.

A personalised training programme will be set up, reflecting your training needs and career objectives. About 20% of your time will be dedicated to this training component, which includes training on the job in assisting in the Bachelor’s and Master’s programmes of the department at Utrecht University.

Your qualities
We are looking for a candidate in coupled subsurface processes in mine water thermal energy storage. You must have completed your MSc degree in Geomechanics, Hydrogeology, Geological engineering, Civil Engineering, Reservoir Engineering, or a related discipline by the time the position starts. Preferably, you will also have:

• experience or strong interest in geomechanical and/or hydrological modelling using continnum-based numerical methods (e.g., finite element method, finite difference method);
• experience or strong interest in rock mechanical experiments, or high-pressure and/or high-temperature laboratory experiments;
• strong quantitative and data analysis skills;
• the ability to work independently and as part of a team in a multidisciplinary research environment;
• enthusiasm for geo-energy and applications relevant to the sustainable use of the subsurface; and
• excellent communication and interpersonal skills.

Due to the international character of our research, good command of spoken and written English is essential. We highly encourage applicants from all members of our community and of diverse backgrounds to join us.

Terms of employment
You will be offered a full-time PhD position, initially for one year with extension to four years in total upon a successful assessment in the first year, and with the specific intent that it results in a doctorate within this period. The gross monthly salary starts with € 2,901 in the first year and increases to € 3,707 in the fourth year of employment with a full-time appointment. Salaries are supplemented with a holiday bonus of 8% and an end-of-year bonus of 8,3% per year. A pension scheme, partially paid parental leave, and flexible employment conditions are based on the Collective Labour Agreement of Dutch Universities.

In addition to the collective employment conditions, Utrecht University has a number of schemes and facilities of its own for employees. These include agreements on professional development, leave arrangements, sports and cultural schemes, and you get discounts on software and other IT products. We also give you the opportunity to expand your terms of employment through the Employment Conditions Selection Model. This is how we encourage you to grow. For more information, please visit Working at Utrecht University.

For informal questions (not for application), contact Dr Wenzhuo Cao at w.cao2@uu.nl or Dr André Niemeijer at a.r.niemeijer@uu.nl.

To apply, please follow the link tot the corresponding advertisement on our own website and follow the guidelines mentioned there. We aim for a wuick selection procedure after the application deadline of June 15th, 2025. The preferred starting date is October 1st, 2025.

Note that international candidates that need a visa/work permit for the Netherlands require at least four months processing time after selection and acceptance. This will be arranged with help of the International Service Desk of our university. Finding appropriate housing in or near Utrecht is your own responsibility and, unfortunately, we must warn that it is a tight market at the moment. In case of general questions about working and living in The Netherlands, please consult the Dutch Mobility Portal.

Online screening may be part of the selection. Commercial response to this ad is not appreciated.