Green Gas Lolland-Falster - Denmark

Client: Energinet

Biogas represents the most widely used source of renewable energy in Denmark. The Energinet project involved constructing three long subsea underpasses using horizontal directional drilling.

The project

The GGLF (Green Gas Lolland-Falster) project consist in building a pipeline to supply gas mainly for sugar factories in Denmark. These factories will be able to develop anaerobic digestion processes with the biogas produced subsequently reinjected into the pipeline.

Our expertise in horizontal directional drilling, which makes it possible to install pipes and conduits beneath obstacles while minimising the environmental impact of operations, enabled us to construct three subsea underpasses, each crossing a distance of around 2,000 m.

This technical achievement was made possible in part through the intersect method, which consists of drilling from both sides of the alignment until the  two boreholes meet, in this case 80 m under the sea.

The challenge

The three underpasses were drilled under very restrictive environmental conditions as there are many protected wildlife species in Denmark. Moreover, the proximity of certain sites with urban areas meant specific noise reduction measures were required. Noise barriers were installed to protect the animals living in the Natura 2000 zone.

From a technical point of view, despite the challenges relating to the geology, composed of a blend of clay and glacial till, as well as the many environmental constraints and project constraints, the project team successfully completed the design and construction phases, building on solid preparation and cutting-edge geophysical studies to optimise the drilling profile.

Three iconic horizontal directional drilling underpasses, stretching 2,000 m at a maximum depth of 80 m, made it possible to avoid the largest rocks and boulders throughout the region.

The project was completed ahead of schedule, to the satisfaction of our client Energinet.