Line-pack storage in biogas infrastructures at regional scale, a model approach

Previously, we reported on a biogas transport model; the model assesses transport costs in a grid with fishbone and star layout collecting biogas. Biogas collection from several digesters to a hub supports the efficient use of resources. A dedicated grid, used for transport, can serve as a form of biogas storage as well. So a model was developed to evaluate line-pack storage in a transport grid for different digester scale, number of digesters, region size, and grid type. Line-pack storage does not require additional investments, and variable costs consist of extra compression costs. In both fishbone lay-out and star lay-out estimated line-pack storage, costs are between 0.3 and 1.5 euroct m(-3)h(-1). In a star lay-out, line-pack storage volume increases with region size. In a fishbone lay-out, the maximum line-pack storage volume is small in both a small size region and in a large region, as a result of pipeline volume and pressure restriction. A comparison of storage costs shows that line-pack storage can compete on costs with pressureless storage, but pressurized pipes are preferred for seasonal storage. A method to describe enlargement of line-pack storage by increased investment in pipelines depending on maximum transport pressure is presented. Such enlargement by applying larger pipe diameters could be financially sensible.