This study aims to assess the role and need of (seasonal) thermal energy storage in the next generation renewable, and sustainable central heating systems for the built environment in the Netherlands. Specifically, the neighbourhood "Karwijhof" in the city Nagele which is transitioning to a collective renewable district heating network incorporating 24 users. The emphasis of this study lies on the technology for storing thermal energy and two different heat collection technologies. The storage of heat is done using an underground seasonal thermal energy storage (USTES), in this case an underground sensible heat storage tank using water as storage medium. The system relies on a small scale district heating network (DHN) for the distribution of heat. For this research two heat collection technologies are considered resulting in two systems to be compared, both incorporating the USTES as main system component. The first system relies on heat collection by solar thermal collectors, the second on an air-water heat pump. Both systems are modelled in the Matlab-Simulink software environment and back tested on historic (publicly available) weather data provided by the Royal Dutch meteorological institute (KNMI). Different system sizes are tested on their key performance indicators through an iterative process. System sizes depend on the capacity of the main components which include: volume of the USTES, surface area of the solar thermal collectors, and air-water heat pump capacity. Key performance indicators include the levelised cost of heat (LCOH) and the seasonal coefficient of performance of the system which gives an indication on the autonomy of the system. To increase the autonomy of the systems a photo-voltaic (PV) array is considered for both systems to offset the electricity use. However, the systems are allowed to exchange electricity with the grid translating into the goal of "zero on the meter" autonomy. The model results show a mismatch between heat demand and generation. Demand peaks during winter from December-March while generation peaks during the summer months May-August. The USTES is needed to overcome this mismatch and ensure access to heat throughout the year. The results show that both systems can ensure heat throughout the year for the users considered during this study. However, systems cannot compete with traditional natural gas heating systems based on the LCOH. This is partly due to the high cost of the district heating network. The systems including a PV array show a LCOH that can compete with the traditional natural gas HR-boiler but are constraint by the rooftop area available during this study leading to a non competitive LCOH. Though, even with enough rooftop area for a PV array the systems cannot pay them self back relative to the base scenario due to the financing costs. During the study no subsidies were taken into account. Subsidies will be needed to make the renewable energy systems presented in this study financially more attractive in the short term. When considering the environmental benefits it can be argued that the systems are already competitive to the traditional natural gas heating systems. Further studies should focus on efficiency gains in the district heating network and the control mechanism of the air-water heat pump. It is expected that the LCOH of systems as proposed in this study will decline in the future as a result of cost reductions and/or efficiency increases of the system components. Also, a lower LCOH is deemed achievable for neighbourhoods with simpler district heating networks (i.e. less meters of DHN piping per user).

Geothermal energy is strongly dependent on the geothermal gradient; this means that with increasing depth an increase in temperature is found. The targeted formation of our research is the Hardegsen which reaches depths of around three kilometers in the West Netherlands Basin. At three kilometers depth the temperature is around 90 C˚ which is interesting for geothermal exploitation. However, rock at increasing depth generally shows a decrease in reservoir properties.
This study investigates whether the reservoir properties of the Hardegsen formation at a depth of three kilometers are still interesting for geothermal exploitation. This is done by determining to what extent the Hardegsen has been influenced by depositional history, diagenetic processes and inversion.
Determining the reservoir properties is done by studying a data set that consists of core descriptions, core plug measurements, gamma ray logs, microscopy analysis, literature studies and a field study. From the core plug measurements a simple model was created describing how porosity and permeability of the Hardegsen behave with increasing depth.
The Hardegsen succession in the West Netherlands Basin consists mainly out of (cross-bedded) arkosic fine to medium grained sandstones intercalated by 0.2-1 meter thick laterally consistent shales and shaly/silty very fine sands. High minus-porosities (up to 45 %) are reported which could have played an important role in the preservation of the reservoir properties. Core plug measurements show that the Hardegsen has good prospects for a potential reservoir with porosities ranging from 10-20% and permeability’s ranging from 50-1000 mD.
The presence of the laterally consistent shale and sandy/silty very fine sand layers is heavily dependent on the location in the reservoir. This research shows absence of these layers in wells that are located closer to the basin margin. Since these layers decrease vertical flow drastically, further investigation of the extent of these layers is needed to give a better prediction of the quality of the reservoir as a whole.