The underground storage will play an important role in the energy transition, both for energy storage as for CCS. Current storage activities in the Netherlands are for natural gas, diesel oil and nitrogen are in both in depleted gas reservoirs and salt caverns. These probably will be extended in the near future with storage of CO2, hydrogen and compressed air.
The Dutch State Supervision of Mines is the regulator who oversees that these activities are performed in such a way that they are safe, now and in the future. This means that the full life cycle has to be considered with a broad perspective on the safety of people and the environment.
The predictions of behaviour of the storage and its fluids and related risk will have large uncertainties due to the level of uncertainty in the subsurface data used, and the limited amount of data to calibrate the models which calculate the risk. In most cases this will mean that the risk can’t be calculated probabilistically. In that case for decision making it is necessary to not only investigate the most likely scenario, but to the range of realistic, possible scenarios to identify the real risk. The period after storage will be orders magnitudes longer than the storage activity itself. This will lead to even larger uncertainties for this phase.
We have to face the fact that we can only partly reduce this uncertainty by further research and monitoring. However research and monitoring can help us to quantify the uncertainty. This emphasizes the importance that operators, policy makers and regulators are able to handle the uncertainties in their decisions before, during and after the storage activities, and communicate openly about them.