Planning for large-scale thermal energy storage systems could be greatly improved

In some places in the Netherlands, the ground is starting to run out of space for thermal energy storage systems, which can provide heating and cooling to large buildings in an energy-efficient manner. There is a much better way to do that, says researcher Marc Jaxa-Rozen. On Tuesday 15 January, he will be awarded his PhD at TU Delft for his work on the subject.

It takes a great deal of energy to heat and cool large buildings. In some places, a lot of energy can be saved by storing heat and cold in underground water reservoirs; this is called Aquifer Thermal Energy Storage (ATES). This method uses natural aquifers (underground water reservoirs). In the summer, surplus heat is used to warm up the water (which is stored underground); in the winter, this heat is released. Cold water is stored as well, which can be used in the summer to cool the building. ‘This approach can cut energy use in large buildings in these parts of the country by 50 per cent’, says researcher Marc Jaxa-Rozen.

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The method is successful. In the Netherlands, ATES is already used in nearly ten per cent of new large buildings. Jaxa-Rozen: ‘The Netherlands, Belgium, Turkey and Sweden are already using ATES on a large scale. The technique is even so popular that there is not much room left for ATES systems in the ground under cities such as Amsterdam and Utrecht. Even today, this has started to hinder the progress of ATES.’
One reason for the lack of space is that ATES systems have always been planned to avoid having an impact on each other. After all, if hot water gets too close to cold water, there will be a loss of efficiency. ‘So the builders always maintain a wide safety margin – too wide, in fact – which comes at the cost of available space.’

Smart systems
This is why Jaxa-Rozen recommends regulatory and other systems where the exact locations of ATES systems can be better coordinated. One way would be to use a system of temporary permits with regular evaluations.
And somewhat farther down the road, smart control systems could also be used that talk to each other to coordinate carefully the different flows of water. These smart grids could exchange information to prevent thermal interference between ATES systems. A simulation of the situation in the centre of Utrecht shows that the density of ATES systems could be increased by 40 per cent through these two improvements.

More information
15 January 2019, 15.00 in the Senaatszaal, Auditorium, Mekelweg 5 in Delft.
Defence of the doctoral dissertation of Marc Jaxa-Rozen: Methods for simulation, planning, and operation of Aquifer Thermal Energy Storage under deep uncertainty.
Promotor: Prof. Paulien Herder (Faculty of Technology, Policy and Management).

To contact Marc Jaxa-Rozen: M.Jaxa-Rozen@tudelft.nl, +31 15 27 87914
TU Delft press officer Sharita Balgobind: U.S.Balgobind@tudelft.nl, +31 15 27 81588