Shore-side power supply of FSU/FSRU at Liquefied Natural Gas Terminal (LNG)

• What was needed: Heavy-duty energy chain for the offshore sector. Emergency shutdown system
• Requirements: flexible energy supply due to the FSU often being in motion, harsh environmental conditions required an emergency shutdown function for the entire system
• Industry: Shipping
• Success for the customer: state-of-the-art energy supply solution, low-maintenance and safe despite difficult environmental conditions

Liquefied natural gas (LNG) is one of the most important energy sources of the present and future, as it emits very low quantities of greenhouse gases and is therefore regarded as an important fossil fuel. In Bahrain, the state authorities have therefore set up a joint venture to plan and build an LNG terminal, which has just gone into operation.
Due to safety regulations, the terminal is located at sea, around three kilometres off the coast. The liquefied natural gas tankers dock at the crossbar and transfer the natural gas to a floating storage unit (FSU), which later pumps the gas via underwater pipelines to a regasification unit on land.
Schneider Electric was responsible for the entire energy infrastructure for this project. In order to supply the floating storage unit with electricity, a connection had to be created between the terminal and the FSU. Not only did a distance of over 30 metres have to be bridged, but the movements of the FSU due to loading and unloading, tides, waves and storms also had to be taken into account. Other criteria included maximum availability and smooth transmission - without electromagnetic pollution.
Finally, it had to be possible to disconnect the connection in an emergency - for example in the event of a tsunami - in a planned manner so that the power is switched off immediately and automatically.

igus® recommended the use of a heavy-duty energy chain, which turned out to be the perfect solution for the application.
The offshore energy chain is attached to the mooring post on the jetty side with a swivel bracket and to the side of the FSU with a removable extender crossbar.
The robust and flexible energy chain system guides and protects two medium-voltage cables. The heavy-duty plastic chain impresses with firmly bolted cable routing and interior separation, is made of special plastics for extreme applications and all tensile forces are absorbed via the internal cables. The use of this special energy chain allowed a passive design without the need for mechanical elements due to the steep movement of the FSU.
The decisive factor was the controlled bend radius of the energy chain, which protects the cables from overbending even during a storm. The cables are equipped with special 3-phase medium-voltage connectors. However, the most important safety element is the emergency shutdown. Martin Tiling, Industry Manager Shore Power at igus®, explains how it works: "In the event of an emergency, we measure the chain length. If the FSU drifts before it is disconnected from the system, the system will first send out an alarm and then initiate the emergency shutdown. After the power supply is switched off, the shore-side connection point of the energy chain can be pulled out of the special attachment point without the risk of arcing.