The study focused on the use of associated and non-associated plasticity models in FEM simulations, with particular focus on the role of the dilatancy angle. The dilatancy angle was shown to significantly influence both the shear strength, the deformation behaviour of soils and the mesh dependence of model outcome, particularly in situations with confined or constrained deformation. To evaluate this, three cases were analyzed: Direct Simple Shear (DSS) test, slope stability, retaining structure.

Projections show that urban areas are growing at an increasing rate and produce 60% of the global greenhouse gas emissions (United Nations, n.d.). In Europe, the thermal energy sector consumes about half of the energy resources, of which 85% is produced by fossil fuel-based energy systems (Drijver, Bakema, & Oerlemans, 2019). As a result of this, district heating companies have set climate targets to
lower the harmful emissions produced by the thermal energy sector. This can only be done by replacing fossil fuel-based energy systems by sustainable energy systems. One of the promising sustainable energy systems is the high
temperature aquifer thermal energy storage (HT-ATES) system. HT-ATES
is a buffer system used to store waste heat from industrial processes in a suitable aquifer and transfers this heat to buildings to heat them up in the winter and cool them down in the summer. However, this system is very complex in use and carries many risks. Due to the HT-ATES being a buffer system, complex in use and carrying many risks there are not many running projects incorporating this system. This makes the revenue model and possible exploitation for commercial use very unclear. Therefor, the goal of this thesis is to develop a business case for the commercial use of HT-ATES systems and to assess the business case sensitivity to the thermal energy demand. The research goal will be achieved
by performing a literature study. Assessing the business case viability against other geothermal energy systems will not be in the scope of this thesis. This thesis is merely meant to gain insight on the business case of HT-ATES systems.

The findings of the research show that a project is solely profitable when the benefit outweighs the cost. The total business expenditure of a 30-year lifecycle HT-ATES project with 3,000 households will be fixed upfront expense of EUR 1,236,991 and an additional yearly expense of EUR 695,795. The benefit of the project is strongly dependent on the thermal energy demand. The revenue model of this project consists of a heating price model and government provided subsidy. This business model assumes a heat price of EUR 3.89 per kWh and a subsidy of EUR 2.73 per kWh thermal energy produced. Assuming the annual thermal energy demand is 12.66 kWh per household, the 30-year HTATES project with a district heating network of 3,000 households will have a payback time of 8.4 years. This means that the project will be profitable after 8.4 years. A sensitivity analysis on the thermal energy demand proved that a HT-ATES will be more profitable if the thermal energy demand is higher. This sensitivity analysis also shows that the project will need to have a minimum of 1,300 households in the network in order to be financially feasible, as the payback time of less households will not be within the project lifecycle. A district heating network with a 30-year lifecycle HT-ATES system will have a payback time of 22 year. When this same network where to incorporate 4,000 households the payback
time will be reduced by a factor of 4.