Artificial illumination on offshore oil and gas installations has a variety of effects on migratory and non-migratory birds, especially at night during foggy or overcast conditions. Birds attracted to platform lighting during the autumnal migration can result in encirclement causing elevated avian mortality rates from bird strike, incineration in the flare (when the flare is in operation) and exhaustion. The problem has been documented for many years from areas as diverse as the North Sea, the Gulf of Mexico and Western Australia (Wiese et al., 2001). The impact of artificial light sources at night on migratory birds is a phenomenon not just linked to oil and gas platforms but also to other illuminated offshore and coastal structures such as wind farms, ships, harbors and lighthouses, all of which contribute to light pollution at night.
Following several years of detailed observations, the Dutch E&P company NAM (Nederlandse Aardolie Maatschappij), established that conventional lights on offshore installations were the critical factor in luring migratory birds to offshore installations and keeping them trapped flying in circles for prolonged periods of time, particularly during so-called ‘broad front’ migration in combination with fog or cloudy weather when all the platforms in the same region experience the encirclement phenomenon.
The following research with the lamp manufactory Philips Lighting, established that the red part of the spectrum in the emitted light was responsible for this circling phenomenon and that removing the long wavelength components of the spectrum reduces the visual and orientation impact on birds (Poot et al., 2008). On the basis of these studies, a light source (spectral modified lighting or green light) was developed that reduces this fatal bird attraction, creates safe working conditions and results in a highly positive public response. The only unresolved safety factor was conflicting opinions on helicopter approach and landing. Circumstantial evidence was found that window glazing with a UV-blue filter – as used in some helicopters - is the cause for this.
This paper reviews the experience regarding the use of spectral modified lighting (and related approaches) and puts them in a new perspective. It elaborates on safety factors, especially those related to helicopter approach and landing and discusses the potential application of the technology for new projects. Drawing on recent experience in Europe and North America to apply spectral modified lighting, the paper address certification and permitting issues and briefly discuss emerging regulatory trends affecting this technology.