Martin Bloemendal presented at the DAP symposium in Delft

Large scale subsurface heat storage is complementary to geothermal energy

The Delft Aardwarmte Project (DAP) started as a student project to develop research, education and own use of geothermal at TU Delft. Meanwhile TU Delft is well aligned to make a final decision to commission the geothermal doublet. Still the students of DAP organize their symposium every other year. This year the theme is: “Integrating cities with geothermal energy”.

During this event I gave a talk on challenges and opportunities for high temperature aquifer thermal systems (ATES) connected to geothermal systems.

Integrating cities with geothermal energy

One key issue in the energy transition is to deal with availability and demand of heat. In urban areas demand is concentrated at a small area as well as during a short time frame: during the winter. Because sustainable sources of heat are scarce and geothermal is hard to implement in urban areas it is important to utilize each source of heat to the maximum. Aquifer thermal energy storage can provide this load-shifting. Thaisa van der Woude from Witteveen en Bos introduced the need for heat storage and how aquifers can be used to provide storage capacity. Her introduction allowed me to in more detail on the challenges and opportunities for the synergy of geothermal and heat storage with ATES. I put the challenge in perspective of the Dutch experience with low temperature ATES systems and fresh water storage in saline aquifers. The scale at which we need to store heat and the physical processes that we need to counter-act to optimize performance (buoyancy) are not “out of league”. Similar problems have been solved, so tackling them for HT-ATES will provide the needed window of opportunity for load shifting, back-up/redundancy and maximum utilization. I illustrated this by using the DAP well equipped with a HT-ATES as a case.

Take home message

There are some challenges to tackle and these are not solved “tomorrow” but surely solvable. When we do so:

  • Aquifers offer time & space for load shifting
  • HT-ATES is complementary to geothermal systems
  • HT-ATES offers back-up/redundancy
  • NL is “on top of things” when it comes to ATES, so if this can be a success somewhere.. it is in the Netherlands.

The DAP symposium and Project

This year’s symposium will focus on the challenges and opportunities of supplying urban areas with geothermal energy. Currently, in The Netherlands, there exist several successful geothermal projects that are producing heat for greenhouses. As today’s technology is improving, more opportunities arise to move the geothermal wells into urban areas, where a high demand for heat is everlasting and large opportunities await. The aim of this year’s symposium is to create awareness of the difficulties and the potential benefits of supplying urban areas with geothermal heat. The symposium intends to look into both technological and policy-based barriers, and seeks to promote new techniques that enable urban geothermal energy, and allow geothermal energy to compete within today’s energy market.

The DAP foundation was initiated in 2008 by students and alumni at the department of Geoscience & Engineering and aims to provide the TU Delft with a sustainable heat source through the realization of a geothermal well on the campus, with the help of several partners from the energy industry. In 2009, DAP acquired an exploration license for the Delft area, in which 4 geothermal wells of 2500 m depth have by now been realized by pioneering greenhouse companies Ammerlaan and Duijvestijn.

Furthermore, DAP seeks to promote the general use of geothermal energy for heating and energy production in the Netherlands by generating and disseminating knowledge for research, education and development. Martin Bloemendal during his presentation at the DAPsymposium (foto credit: Beerd Volkers).


Storage potential during summer, to supply during peak demand.