Transport network and whole-chain model

Existing natural gas pipelines in Germany and in neigbouring countries (according to project EU GeoCapacity) Source: BGR/GeoCapacity

In this work package following aspects were investigated:

• technical designing of pipeline network (e.g. dimensions, material, pressure, incoming and outgoing mass fluxes as a function of time, compression scheme),
• identification of techniques for mass flux measurements in CO₂ pipelines (metering devices),
• calculations of impacts of load and pressure variations on transport und injection; definition of respective feasible tolerance ranges,
• comparison of pipeline transportation with option "ship transport"; designing of the interface between onshore pipeline and ship (including interim storage),
• predictive calculations on potential impacts of CO₂ injection on the ground surface and surface installations/infrastructure,
• set-up of a techno-economic whole-chain model and sensitivity analyses to identify key control factors of feasibility and costs of CO₂ capture, conditioning, transport and injection/storage.

A techno-economic whole-chain model was set up for the base scenario. Based on the whole-chain model the feasibility of transport, injection and storage was assessed as a function of CO₂ stream composition and variation in overall mass flow rate. Also, related investment and operational costs were estimated. For this, different design options for the regional pipeline network connecting emitters within the cluster and for the trunk line (300 km onshore and 100 km offshore) were compared. For comparison, also ship-based transportation of CO₂ was considered in the offshore section.

Section of the geological model of a fictive storage site as defined in the base scenario (not drawn to scale; point of injection denoted by grey line in the middle of the section) Source: BGR

When defining feasible tolerance ranges of load and pressure variations as well as of CO₂ stream composition during pipeline transportation, knowledge of the boundaries of the multi-phase regions of different CO₂-impurity mixtures is of particular importance to avoid phase transitions during operation. The boundaries of the multi-phase regions depend on prevailing pressures and temperatures and on the CO₂ stream composition.

In addition, we were investigating if pressure variations in the storage reservoir during injection may result in a deformation of the ground surface with implications for surface installations/infrastructure.