Saft maintenance-free, lightweight nickel-metal hydride (Ni-MH) battery modules are providing vital power for the innovative, self-contained, photovoltaic-powered navigation lights developed by Sabik Informationssysteme, the navigation aid specialist, for marking abandoned offshore structures in the Frigg North Sea oilfield

The decommissioning of the offshore structures involves removal of the main superstructure (topsides and jackets), leaving the concrete gravity bases that still need to be marked as a hazard for shipping. Since local generation is no longer available the marker light has to provide its own autonomous power. The removal of the helipad also means that the light has to be installed without landing on the structure.

Sabik has developed the self-contained light for Total E&P Norge AS in cooperation with the oil industry engineering specialist Liaaen Teknologi AS. The design is based on key criteria defined by Kystverket (the Norwegian Coastal Administration) and Scotland's Northern Lighthouse Board (NLB) including: four years of maintenance-free operation; 10 NM (nautical mile) navigation light and Racon (Radar Beacon); PV (Photovoltaic) power supply; satellite based remote monitoring; redundancy of vital systems; installation by helicopter.

The 12 V battery system is required to store sufficient energy from the light's PV modules in the spring and autumn months to ensure reliable winter operation. Saft has engineered a battery solution for this application based on Ni-MH batteries - the only suitable technology in this case - since they are sealed for life, requiring no topping up with distilled water or other maintenance. They easily meet Sabik's requirement that the entire system should provide four years of maintenance free operation and, with an anticipated service life of up to 15 years, they will provide reliable power for several tours of duty.

The batteries are based on Saft NHE battery modules. They provide good energy density and maintenance-free operation with a high cycle life and are fully recyclable at the end of their life. A typical installation will comprise a 500 Ah battery to power one or two LED navigation lanterns, a 300 Ah battery for the Racon and a 100 Ah battery for the satellite based remote monitoring system that provides detailed information about the operation of the onboard systems.