Geothermal energy and thermal energy storage: a winning combination!?

On 13 April 2021, in one of the series of WarmingUP webinars, Hilde Coppes from Shell and I talked about how thermal energy storage can increase the use of the heat available from a geothermal energy well.

Geothermal energy and heat storage are often a winning combination, because the temporary storage of summer heat for its later use in the winter leads to more sustainable heat being supplied to more buildings. As a result the geothermal project becomes more profitable financially, while the customers pay less for their heating.

Curious about how this is possible? Take a look at the webinar!

Also meeting peak demand sustainably

A geothermal energy project typically supplies baseload heat. The demand for heat varies however, and in the winter the geothermal well cannot meet the demand requirements, while in the summer the available heat exceeds the demand.

Heat supply and demand and storage potential [Hartog, N., M. Bloemendal, E. Slingerland and Wijk. A. van (2017). “Duurzame warmte gaat ondergronds.” VV+ sept-okt 17.]

Through the seasonal storage of the summer’s surplus production using Aquifer Thermal Energy Storage (ATES), a large amount of heat can be stored and subsequently be used to meet (most of) the peak demand for heat as well. The process is illustrated in the figure below.

Schematic representation of the operation of the combination of heat storage and geothermal energy. The left / shallow sources in the figures is the heat storage (see the difference in pumping direction between winter and summer. The deep / right sources is the geothermal system, which always produces from the same source.

A hot topic for deep research

The aim of WarmingUP is to develop collective heating systems that are affordable, sustainable, reliable, feasible and socially acceptable.  KWR is making a wide-ranging contribution to WarmingUp, by leading the aquifer thermal energy storage theme (WINDOW), and by participating in the research on the themes on aquathermal energy, geothermal energy and the social integration of sustainable heating networks.

The aim of the WINDOW programme is to eliminate technical, legal and commercial obstacles, and to establish a clearer picture of the impact on the responsible use of underground thermal energy storage, for the purpose of enhancing the sustainability of the heat provision in the Netherlands. We are doing this by supporting exploratory studies and (the preparation of) demo projects in the country, and by sharing the resulting knowledge and experience and applying it to the joint development of generic tools, in close collaboration with stakeholders and policy-makers. The ultimate objective is to enable the implementation of underground thermal energy storage as a proven technology in 2025. The results will contribute to reducing the costs of collective systems at the system level, and to an optimal exploitation of sustainable heat sources.

WINDOW status update

The webinar brought together different aspects of the WINDOW programme, offering a good glimpse into the current status of the research programme. We showed that the application of energy storage has a great potential at different demo sites, and in two of the three cases this involved a combination with geothermal energy. It has also now become clear what the generic work packages will focus on, because the exploratory studies have revealed which information/knowledge is most needed in order to make energy storage a success, namely:

  • Well design: new design standards for critical flow speed with no clogging, taking higher temperatures and water treatment into account, and considering how losses and impact can be minimised.
  • Data acquisition: not much is known about many of the ground layers we want to use for energy storage. To make a good design, and to be sure that energy storage is at all feasible, it is important that we collect as much reliable information as possible on the properties of these layers.
  • Impact and performance: development of standards and methods to enable the effective and reliable monitoring of the energy storage system during the operational phase.
  • Laws and regulations: a clear assessment framework, which makes it unnecessary for provinces to conduct tailored assessments in each case, and also makes the approval prospects of a potential energy storage system much clearer for the initiators.

Work is therefore currently in full swing on these aspects of the generic work packages. At the same time, the data acquisition, the definitive design and the integration for the demo sites also keeps on moving ahead!