Aquifer Thermal Energy Storage (ATES) is a geothermal technique that is an important component in the transition towards renewable energy in the heating and cooling industry, which accounts for half of the world's energy consumption. However, the technology has not yet been implemented in many countries. The main reason is that extensive preparation and site-specific analysis are required for the implementation of ATES systems and many stakeholders need to be involved. These stakeholders are typically unfamiliar with the technology and unaware of the potential applicability. To stimulate stakeholders and the decision-making process within the ATES sector, several studies emphasise the necessity of examining the potential of ATES technology on a local level. Such potential studies support ATES decision-makers as they evaluate the technology, potential scale and its commercial viability.

The objective of this research is therefore to develop a methodology to determine the technical and commercial potential of ATES while incorporating local characteristics. Until now, ATES feasibility studies have mainly been focused on large-scale ATES suitability. For generating more representative results, however, this new methodology also incorporates local geohydrological conditions and the interests of and restrictions imposed by its local ATES stakeholders. The methodology can be applied globally to every region that has available aquifers and moderate climate conditions. The developed methodology in this study is applied to the region of New York State (NYS). High expected energy savings and promising geothermal trends are among the main reasons for this geographic selection. Moreover, no commercial ATES project is yet in operation in the US, a country of which the potential energy savings are expected to be highest in the world. A successful introduction of the technology in NYS could therefore function as a valuable use-case for many other states in the US and also for other countries.

Firstly, the stakeholders in NYS are identified and analysed in this study. They are assessed based on their level of influence, attitude and their ability to solve current barriers that are preventing ATES from being adopted. This analysis indicated that geothermal architects are the most influential stakeholders and are therefore essential to engage for the successful implementation of ATES in NYS.

Secondly, the technical and commercial ATES potential is examined by analysing local geohydrological conditions, building characteristics and the identified requirements from geothermal architects. It is concluded that over 99\% of all buildings in Nassau County (around 400,000) could technically receive the required amount of heat and cold if an ATES system was installed for those buildings. Moreover, it is found that for buildings with ATES systems, heating is twice as efficient as conventional methods in Nassau County and cooling is even 10-30 times more efficient, depending on ATES design parameters. Furthermore, it is concluded that ATES is already a commercially attractive solution for 385 separate buildings in Nassau County, accounting for an estimated 10\% of the total heating and cooling demand of buildings in the county. This number is expected to increase significantly when multiple buildings are connected to a single ATES system.

This research shows that ATES is a technically and commercially viable geothermal solution for buildings in NYS. Therefore, it is critical that ATES is included in the existing evaluation tools developed and currently used by the city and state authorities of New York. The methodology developed in this study is characterised by the inclusion of local characteristics such as the interests and requirements of a region's key stakeholders and local geohydrological conditions, which are found to be essential to generate realistic and accurate insights into the technical and commercial potential of ATES. The model that has been developed is scalable and can be applied to other regions and the accuracy of the model can be increased further by also incorporating groundwater models in the analysis. All in all, the methodology developed in this study offers valuable support for local decision-makers and is an effective resource to increase the adoption of ATES technology worldwide.