Is the Porthos project safe for its surroundings?

Safety is one of the most important preconditions for Porthos. , both for the people involved in the work on the route and for local residents and surrounding businesses. Both during the construction of the transport network of great importance to local residents and surrounding companies and also in the operational phase; once the system is in use. An environmental impact report (EIA) was prepared in June 2020. The Ministry of the Interior and Kingdom Relations (BZK) is the initiator for the plan part of the EIA and Porthos for the project part. Royal HaskoningDHV wrote a public summary of the MER on Porthos infrastructure, which is publicly available.

Construction phase
Porthos’ land pipeline will be located in the existing pipeline strip along the A15, via Botlek-Vondelingenplaat to the Maasvlakte. The land pipeline is approximately 30 kilometres long. Working in the pipeline strip does require a great deal of coordination.

Strict guidelines and fixed procedures apply to work in the pipeline strip. Our contractors must work according to the rules laid down in the City of Rotterdam’s ‘Pipes Manual’. This manual is not a guideline but has legal status.

Before starting work outside, there was a lot of consultation with the managers and owners of the existing cables and pipelines in the project area. A logical consequence of the fact that transport in the port of Rotterdam is probably even busier underground than above ground. The consequences of disruptions in the cable and pipeline strip are far-reaching; product loss, process downtime and even the creation of dangerous situations when factory processes stagnate. The role of pipeline owners and operators is great for this reason. By working together according to fixed procedures, we ensure the safe location and use of the pipelines.

Operation phase
As soon as the Porthos system goes into production, CO2 gas flows through the pipeline system. The pipeline, compressor station, platform and wells are designed with all relevant safety standards to minimise the likelihood of any unforeseen events. CO2 is neither explosive nor flammable. There is a very low safety risk in case of leakage into the Porthos infrastructure. If so much CO2 is released that it displaces oxygen from the air as a CO2 cloud AND there is long-term exposure to a very high CO2 concentration, this could be dangerous to human and animal health.

Leaks in the land pipeline could be caused by work in the pipeline strip, damaging the pipeline. The pipeline is continuously monitored. If leakage occurs, it is quickly reported and resolved so that the volume of CO2 released is limited. The pipeline can also be affected by corrosion. The chance of this happening is small because the pipeline is protected against corrosion by a protection system and a coating around the pipeline. Especially for Rozenburg, a response plan is being developed in cooperation with the Rotterdam Safety Region for all possible scenarios.

The compressor station and platform on the North Sea are at a great distance from buildings, so there are only risks for the company’s own personnel. Personnel are trained in how to deal with this and provided with the necessary safety equipment.

If the pipeline is damaged underwater and a large leak occurs, the effluent CO2 will immediately mix strongly with the water. As a result, a gradual flow of CO2 will rise to the surface. This may affect passing vessels. The risks are similar to existing risks as there are many gas pipelines under waterways.

The CO2 will be stored at a depth of 3 to 4 kilometres under the North Sea. The wells, so-called P18 reservoirs are located in a rock layer that is millions of years old. The natural gas in these wells that was previously extracted is in sealed sections. The injection of CO2 will increase pressure in the reservoirs, but strict control measures ensure safe storage. There is also concern about possible ground rise and risks of earthquakes, although the likelihood of this is small. The risk of CO2 leakage is considered negligible; to further mitigate the risks, well walls are periodically checked and there are control measures for well walls and fractures.

In the first 15 years after the Porthos system is operational, the gas field is filled by Porthos itself and continuously monitored so that any leakage is quickly recognised. The State Supervision of Mines monitors the monitoring. After removal of the wells and platform, direct monitoring is no longer possible. By then, the reservoirs have been found to have been shut off for some time. Should leakage occur, it will occur to a very small extent and will be trapped in the overlying rock layers. After completion of the CO2 injection, the reservoirs will be safely sealed.