High Temperature Open Ground Energy (HTO) system

Test drilling is being carried out on the campus in preparation for the construction of an underground thermal storage system: High Temperature Open Ground Energy (HTO) system. The HTO system is one of TU Delft’s initiatives as it heads towards a CO2-neutral, circular and climate-adaptive campus by 2030. This system enables the storage of excess heat production from the geothermal installation in the summer, which can then be used during periods of increased demand in the colder months. By doing this, we make the most efficient use of the geothermal heat source. The test drilling will map the soil conditions to a depth of approximately 200 metres. The results will allow us to determine the best storage depth for the hot water.

Scientific research
The on-campus HTO system is part of PUSH-IT and Warming-up-GOO, a European and a national research programme into underground heat storage, respectively.

Facts and figures

  • Depth: approx. 200 meter
  • Storage volume: approx. 500.000 m3
  • Temperature lukewarm spring: 40-55°C
  • Temperatuur hot spring: 75-80°C
  • Amout of heat: approx. 40 TeraJoule


  • End of March 2024: start of test drilling operations
  • End of May 2024: completion of test drilling
  • Depending on the test drilling and the research results, decisions will be made regarding the further construction of the system

More information

For more information about the work, please contact secr-crefm@tudelft.nl.

More details about the research programmes and what is specifically being researched at the TU Delft Campus can be found at www.push-it-thermalstorage.eu/ and https://www.warmingup.info/.

Want to read more about Martin Bloemendal’s research? Read his ‘Story of Science‘ about underground heat storage on campus.