As the energy transition accelerates, there is growing interest in exploring different renewable energy sources to help reduce emissions from heating and electricity. One of the more promising options, under the right conditions, is geothermal energy, which can provide a stable and relatively low-carbon supply of heat and/or power. In the Netherlands, medium-depth (>500 m) geothermal heat has mostly been used for heating greenhouses, with electricity production from geothermal sources not yet explored.

This thesis provides a techno-economic assessment of medium-depth geothermal energy systems in South Holland, the Netherlands, evaluating their potential to meet local heat and electricity demands sustainably and with a profit. Two case studies were analyzed in this thesis. The first investigated a geothermal district heating system for the TU Delft campus, incorporating a large-scale heat pump to increase heat extraction from the reservoir. The second examined a combined heat and power (CHP) system for the Royal IHC facilities in Kinderdijk, based on an Organic Rankine Cycle (ORC). The work relied on thermodynamic modeling together with subsurface and economic simulations to select working fluids, size the main components, and assess economic indicators such as Levelized Costs of Heat/Electricity (LCOH/LCOE), Net Present Value (NPV), payback times, and internal rate of return (IRR).

The findings reveal a sharp difference in feasibility between the two cases. The geothermal heat pump project in Delft proved to be promising for district heating applications, whereas the ORC-based power generation system proved to be both technically and economically unviable under the assessed conditions, mainly due to the low temperature of the geothermal brine and the small scale of the project. A subsequent evaluation of a heat pump alternative for the Kinderdijk site indicated limited economic competitiveness under the current market price assumptions for heating.

Overall, the work suggests that the viability of geothermal projects is highly dependent on the quality of the geothermal resource, the scale of implementation, and the end-use requirements. Integrating heat pumps with medium-depth hydrothermal resources appears as a technically promising and financially attractive strategy for decarbonizing district heating networks, whereas low-temperature ORC systems for power generation remain unsuitable in regions with insufficient subsurface temperatures. The study shows the importance of site-specific assessments in ensuring the successful deployment of geothermal energy systems.

The energy crisis and climate change, is creating an urgent need for sustainable and energy-efficient solutions. A significant portion of global energy consumption comes from households. Within this sector, the largest share is used for space heating and cooling. Therefore, efforts to reduce energy usage and cut carbon emissions should primarily target heating and cooling systems. A promising solution to this challenge lies in harvesting shallow geothermal energy through technologies such as energy piles, which have a multifunctional role to the building.

Energy piles are a specialized form of Borehole Thermal Energy Storage (BTES) systems that utilize shallow geothermal energy by taking advantage of the ground's stable temperature throughout the year. They are gaining popularity as an efficient solution for both heating and cooling, primarily because they serve a dual function within a building. On the one hand, they act as heat exchangers, enabling the transfer of thermal energy to and from the ground. On the other hand, they provide structural support, as they are typically constructed from reinforced concrete. This multifunctional role makes them a cost-effective choice and reduces the initial costs investments. These systems are commonly integrated with Ground Source Heat Pumps (GSHPs), which facilitate the exchange of thermal energy between the energy piles and the circulating fluid within the system. Their high Coefficient of Performance (COP) and environmentally friendly operation contribute positively to the transition towards more sustainable energy solutions.

This research focuses on an existing energy pile system located beneath a building on the TU Delft campus, which is responsible for covering the building's heating and cooling demands. The main objective of this research is to assess how the efficiency and reliability of this system can be improved through the implementation of advanced control strategies. To achieve this, a precise simulation model was developed to capture the underlying physical processes and monitor key performance indicators. Energy balance is a key metric and evaluation point for the system that secures the efficiency and sustainability of it. Additionally, various scenarios with different operational parameters were designed to evaluate the system's capabilities and performance.

The main findings initially indicated that the heating load is higher than the cooling load, revealing a significant imbalance. By creating various scenarios with different temperature setpoints, heating and cooling months, and durations of heating and cooling modes, an energy balance was achieved. However, the system was still unable to adequately cover the energy needs of the building during winter. Scenarios that utilized solar gains —by opening the building’s sunblinds— enabled the heating and cooling system to supply the majority of the heating load during winter. This aligns with one of the main goal of the system while maintaining energy balance throughout the year. Among the scenarios evaluated, scenario 5 demonstrated the highest heating and cooling energy delivery. According to performance evaluations, it also consumed the least electricity among the compared scenarios. Additionally, Scenario 5 provided the highest levels of visual and thermal comfort for occupants, as the sunblinds remained open during non-operational months. The system was found capable of operating under loads 50% higher than normal, although these levels push its operational limits. Moreover, it was observed that the energy piles system can store surplus energy during summer and completely cover the heating demand of a neighboring apartment.

The thermal plume interaction is investigated thoroughly and shows the rate and the magnitutude of the expansion or contraction of those. It was observed that energy is lost due to the open boundary with the ambient air temperature but varies between the scenarios. More details will be discussed in the following sections.

The growing energy demand, along with more greenhouse gas emissions, highlights the need for renewable alternatives to fossil fuels. One promising option for space heating is aquathermal energy from surface water (TEO), especially in areas with a significant amount of surface water. However, TEO systems generally require substantial spatial integration, which poses challenges in dense urban areas such as the historic city centre of Amsterdam. In particular, limited (sub)surface space and existing infrastructure complicate implementation. Quay walls may offer a potential solution for the spatial integration of TEO, but the conditions under which this would be technically, spatially, and economically viable remain unclear.

This research investigates the feasibility of utilising TEO in historic city centres, with a case study in Amsterdam. It focuses on the potential for integration into quay walls. A linked modelling approach was used to assess the spatial requirements, CO₂ reduction, and investment costs under various heating demand scenarios and system base loads. Heating demand was varied based on different retrofitting levels, and first-order TEO system designs were developed accordingly.

The results of the study indicate that a higher base load to be covered by the renewable source (TEO), combined with less retrofitted buildings results in significantly higher spatial requirements. This could potentially complicate quay wall integration. However in most scenarios, TEO systems could be integrated into the quay walls.

The CO2 reduction was assessed for all scenarios. For increased base loads covered by TEO systems and high retrofitting levels of the buildings, the CO2 reduction was the highest. This would outperform the all-electric scenario.

Financially, the lower retrofitting levels would result in slightly lower investment costs per dwelling. The effect of a higher base load delivered by TEO systems was found to be relatively minor. Although the TEO systems require a significantly higher financial investment, the national costs could be lower. This should be studied further in future research.