Lighting for offshore energy applications

Offshore wind projects normally require five years’ warranty from float out or even commissioning the farm, so it is critical to supply high quality products that can withstand this time out at sea, particularly as replacement costs on offshore wind farm projects are extremely high. Operation and maintenance activity accounts for approximately 25% of the lifetime cost of an offshore wind farm.

Typical applications for lighting include walkways, stairways and ladders, crew access, control room, doorways and the turbine identification board. Before making a choice on lighting, a number of factors should be considered for each application, from the control room and turbine down to the foundations:

Nacelle/Control Room

Safe access to the nacelle is required for most maintenance activities. Although ladders are always required, larger wind turbines also have an elevator. To protect all nacelle components from corrosion, the nacelle is well sealed. The nacelle cover provides weatherproof protection to the nacelle components, as well as support and access to external components. Reliable, high quality lighting is required to facilitate safe personnel access and exit from the nacelle and tower.

In a confined space, it is an advantage to have low profile luminaires, as space is a challenge when performing work tasks inside the control room. Lighting is normally fitted to the ceiling or walls, with exit lights installed at doorways. Emergency lighting is also required to maintain safety in the event of a loss of grid power. Lighting should be marine-tested and quality approved.  

Turbines/Towers

The design life of an offshore turbine is around 25 years. The trend for longer design life on all turbines is due to the maturing of the industry – asset owners now expect to operate wind farms for such periods without the technology becoming obsolete or unsupported by suppliers. Extreme loads due to storms, abnormal events and faults during operation can also be critical. Typically, an offshore turbine will turn for over 90% of the time, so it is important to choose a lighting supplier that has plenty of experience of marine and offshore environments and luminaires that will achieve the intended lifetime of the turbines.

Foundations/Transition Piece

The floating or fixed foundations provide support for the wind turbine, transferring the loads from the turbine at the tower interface level to the sea bed where the loads react. The foundation also provides access for personnel from vessels. Unregulated vibrations result in excessive material wear, which in turn can (and does) cause component failure. A lighting supplier should therefore offer vibration testing of the light fixtures. Glamox, for example, performs three types of test: Sinusoidal vibration, various shock/impact tests, and random testing.

Lighting should be installed at the crew access point to the foundation, as well as lighting the escape to sea. This area sits above the supportive structure and is accessed via a bridge from the crew transfer vessels. Therefore, safety requirements dictate that high quality marine lighting is needed to ensure these areas are well lit. Typically, linear lighting will be installed on handrails, floodlights for lighting the escape to sea and for illuminating the turbine identification plate, as well as part of the turbine.

Substation topsides AC and HVDC

The substation is the most important structure in an offshore wind farm. This is where all the energy produced by the wind turbines is brought together and converted by transformers to a high voltage transmission. This is necessary to ensure that as little energy as possible is lost during transmission over long distances to the next grid node.

If a technical fault occurs on the substation platform, all wind turbines in the offshore wind farm will fail to function. This means that maintenance and repair services must meet extremely meticulous and high quality standards. All electrical products, including lighting, are potential emitters of electromagnetic waves. This means that lighting should be marine-certified and tested according to both EN-55015 and EN-61547.

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