Abstract
This paper presents a case study on a near-shore gas field in the Dutch North Sea for a seasonal storage scenario. A subsea development was considered, connected by pipeline to an onshore processing facility. Reservoir simulations were carried out to model the mixing of the hydrogen with the in-situ natural gas and to estimate the composition of the back-produced stream and its variation during and between the individual cycles. The required sizing of the processing facilities was determined through process models, and the pipeline sizing through a hydraulic assessment. The development considered new wells, which were designed to deliver the assumed hydrogen production rate at the end of a production cycle when contamination is highest. The investment and operational costs of the complete facility were estimated as well as emissions of the storage operations.
The study enhanced the understanding of the technical scope and technology gaps; as well as the economic, environmental, and energy performance of underground hydrogen storage. It highlights main cost drivers and delivers insights into the re-purposing potential of the existing infrastructure. An example insight gained from the study was that the disposal (or utilization) of the waste stream from gas separation could pose a real challenge particularly in an offshore environment, given its intermittent character, the highly variable and partly unpredictable composition, its large flow rate, and its near-atmospheric pressure when using a Pressure Swing Adsorber for separation.