High Temperature Aquifer Thermal Energy Storage in the Utrecht Science Park
An ongoing project with a promising sustainable technology
The top few hundred meters underground of the Utrecht Science Park offers excellent opportunities for seasonal High Temperature Aquifer Thermal Energy Storage (HT-ATES), a process which involves sustainably heating water to around 90° C in the summer for use in colder periods.
This is the conclusion reached by researchers from the Faculty of Geosciences and TNO Geological Survey of the Netherlands, as well as consulting and engineering firm IF Technology, following a novel long-term and meticulous study of the characteristics of the local subsurface. The research is not only relevant in the context of the energy transition but has also yielded valuable new scientific insights. Based on this exploratory subsurface research, the Executive Board of Utrecht University has approved the drilling of a monitoring and exploration well, preceding the final investment decision for constructing the geothermal storage site and associated technological developments. These drilling operations and associated testing of the target reservoir are scheduled for the coming academic year.
Thermal battery
The research is being carried out as part of the ACCEL-UTES (Acceleration of Underground Thermal Energy Storage) project dedicated to building a High Temperature Thermal Energy storage site at the USP in the larger framework of the East Utrecht area. ACCEL-UTES is investigating the possibilities of heating water during the summer, when there is a surplus of renewable energy, and storing it underground. Subsequently it can be used to heat buildings during cold months. This application can also provide flexibility to the electricity net and reduce grid congestion by converting electricity to heat. The Netherlands is at the forefront of this technology and the project advances the UU as a national and international leader in the energy transition, acting in line with its academic responsibility and societal ambitions.
High-temperature energy storage is highly suitable for heating existing buildings
Sustainability
“High-temperature energy storage at the USP is of high interest for a number of key sustainability reasons,” adds Jan-Diederik van Wees, UU Professor of Geothermal Exploration and TNO principal scientist. “It would drastically reduce our dependence on gas and make a significant contribution to our sustainability ambitions. High-temperature energy storage is, in fact, highly suitable for heating existing buildings since the heating systems were largely designed and installed at times when heating by means of hot water was the norm. Therefore, in contrast with low-temperature heating, no major new construction or renovation is required.”
Unique
The Netherlands is a global frontrunner in HT-ATES development. What makes the HT-ATES at the USP unique is that the primary source of sustainably generated heat is the conversion of surplus renewable power in summer time. The project may potentially lead to a reduction of the USP CO2 emissions by more than 50%, is price-wise competitive with gas-fired heating costs, and contributes to the resilience of an energy supply less vulnerable to external factors.
The underground of the USP had never been studied in the required detail before the ACCEL-UTES research
Subsurface imaging and prediction
The application of these types of subsurface energy storage technologies requires significant preliminary research and novel predicting methodologies. “Unlike areas in the Netherlands where oil or gas was extracted, the underground of the USP had never been studied in the required detail before the ACCEL-UTES research,” explains Liviu Matenco, UU Professor of Tectonics and Sedimentary Basins. The researchers took advantage of an EBN geothermal programme that sent controlled vibrations into the ground at various locations on the East Utrecht area, which were picked up elsewhere by special sensors called geophones and translated into images of the subsurface, a technique comparable to medical ultrasound. By a new technique of reprocessing these reflection seismics images correlated with available information and validated by novel numerical and machine-learning approaches, the UU-TNO researchers were able to roll out, as it were, a fine-mesh net that provided a detailed overview of the underground properties. Analysis of these properties revealed, among other things, that it is highly likely that several geological layers beneath the USP are suitable for the storage of high-temperature energy.
Additional benefits for scientific community
The Utrecht underground is also of interest from a purely research novelty perspective: it is characterized by a number of geologically old fault lines affecting and controlling an ancient deltaic system that formed in the distant past. “Thanks to this research, we have been able to characterize these novel findings in detail,” says Matenco. “Therefore, the construction, operation and continuous monitoring of the HT-ATES would not only fit in seamlessly with the strategic theme Pathways to Sustainability but also benefit future generations of researchers and students in the geo- and energy sciences, giving them direct access to data, novel methodologies and operational experience.”
Joining forces
The research is a fine example of the close collaboration that has been taking place for some time between Utrecht University and TNO Geological Survey of the Netherlands. This collaboration was recently formalised when both parties signed a cooperation agreement on 21 May.
The project was carried out with a Top Sector Energy subsidy from the Ministry of Economic Affairs and Climate Policy, and a national EZK and LNV subsidy scheme, implemented by the Netherlands Enterprise Agency (RVO).