Underground storage

The subsurface of the Netherlands has been a prolific source of raw materials and energy, key to the country’s economic, technological and welfare development. However, due to the significant decline in domestic hydrocarbon production, especially natural gas, and despite the increase in geothermal projects, the subsurface is transitioning from being a provider of energy and resources to a provider of storage services, such as underground natural gas storage. This shift aligns with the current transition to renewable energy, increased energy imports, and global environmental and climate challenges. Recent studies on the future energy system of the Netherlands point to the need for a (large) underground storage capacity, which can also facilitate the permanent storage of residues from energy production and conversion (e.g. wastewater and CO2). This need arises from traditional variations in energy demand, such as seasonal heat demand, and the increased share of fluctuating energy production from renewable sources like wind and solar. Aboveground facilities can provide short term storage, but the surface space required for mid-to-long-term storage would be extensive, making underground storage solutions essential. In the Netherlands, there is a rich and broad knowledge of the subsurface derived from long-standing and large-scale exploration and production activities for natural resources. This knowledge allows for the potential use of large underground volumes in depleted oil and gas fields, aquifers, and engineered cavities. Coupled with ongoing research and development of various storage technologies and the growing need for flexibility services to balance the system and secure energy supply, this makes it feasible and attractive to store large amounts of energy (GWh to TWh) underground in the form of gas, liquid, heat, and mechanical power. Current research focuses on identifying suitable geological formations on- and offshore and assessing the technical, economic, societal, and environmental feasibility for safe, efficient, and timely deployment of underground storage. Pilot and demonstration projects are crucial for scaling up and commercializing underground storage technologies (e.g. CO2, hydrogen). It is important to realize that the successful integration of underground storage into the energy landscape requires informing and involving local communities and authorities at all stages of the project. Only in this way can underground storage contribute to a smooth transition towards a clean and climate-neutral future energy system.