Characterisation of Aquifer Thermal Energy Storage for applications in the UK

Abstract

Aquifer Thermal Energy Storage (ATES) is a proven technology to provide low carbon space heating and cooling. Counting more than 3000 deployments, the Netherlands is the current market leader. Other countries, such as the UK, despite a large potential, only comprise a handful of installations.

This thesis provides an overview of the current state of ATES in the UK, reviewing active installations, encountered challenges and opportunities for growth. To illustrate the potential for ATES in the UK, a case study of an ATES system is reported: the Wandsworth Riverside Quarter ATES which targets the Chalk aquifer. Monitoring data is used to assess the performance of the system, demonstrating the feasibility of ATES systems in geologically complex aquifers, such as the Chalk.

Uncertainty in subsurface response is an important challenge when designing ATES deployments. Target aquifers for ATES in the UK, such as the Sherwood Sandstone or Chalk aquifers, comprise important geological heterogeneity, rendering predicting the subsurface response challenging. Therefore, a numerical modelling approach for ATES with dynamic mesh optimisation and surface-based modelling is introduced. The use of dynamic mesh optimisation is demonstrated to speed up simulations compared to using a fixed mesh by up to a factor of 15.

Numerical modelling can also be an important tool to derisk deployments, for example ensuring that groundwater quality is not compromised during ATES operation. The modelling approach that was previously introduced is applied to investigate the risk of contamination during ATES operation in aquifers where a shallow freshwater/saltwater interface is present. Two non-dimensional parameters are introduced to allow for rapid assessment of contamination risk at the well heads and downstream, for a given ATES system operating in a homogeneous aquifer.

This thesis provides learnings and tools for key stakeholders to support the sustainable development of ATES systems in the UK.