Lights Out for Halogen?

Does the introduction of new LED technology signal the end for traditional airfield lighting?

Tuesday, December 30, 2003

Airport World Magazine
Airport World
Volume 8, Issue 6

Although few airports yet to fully embrace it, the rapid development of Light Emitting Diode (LED) technology leaves little doubt that a new type of light will be used to illuminate the world's airfield in the years ahead.

A handful of low-key LED airfield lighting trails are currently taking at major airports like London Heathrow, Amsterdam Schiphol, Frankfurt, Miami and Singapore Changi and many more are believed to have expressed an interest in the technology, which has been slowly introduced to the market over the last 18 months.

Many of the major lighting companies have made their first LED sales in the last year, and while order books for the new equipment may not be overflowing, they are beginning to fill up to fill up even though the technology is still in its infancy in the airfield lighting world.

So what exactly is the difference between LED and traditional airfield lighting? What can LED do that today's lighting can not and why haven't any major airports invested in the new technology to date?

LED lights use a semi-conductor that emits light when a direct current flows through it. The concentration of emissions on a small area making it easier to project light in a specific shape or direction without losing integrity. The downside of the light concentration, however, is that it makes it physically difficult to create a high intensity without affecting other operational parameters such as heat and lifetime.

Traditional tungsten halogen lights produce light from photons created by a heated tungsten filament. The light beams is orientated by a reflector and/or lens and coloured through use of a filter. The "life" of the lamp is depended on the evaporation of the tungsten from the filament, a phenomenon slowed down by the recycling effect of the halogen gas. The lamp fails when the tungsten filament becomes fragile through usage.

Bruno Urbain, marketing manager for advance technologies at Siemens owned ADB, believes there is no comparison between LED d the lights used on today's aprons and taxiways.

Says Urbaing: "LED lights are the future. They last longer, are cheaper to operate and will enhance airfield safety. The long lifetime of LED light source- each lasts from 56,000 to 100,000 hours compared to the 1,000 to 1,500 hour lifespan of a halogen bulb-ensures low maintenance costs and better traffic flow due to not having to constantly close taxiway to change burnt out lamps. Each LED light uses between 15 and 30 watts of power compared to the 45 to 100 watts needed by traditional halogen fixtures, meaning that LED will reduce the energy bill of an airport at the same time as lowering greenhouse gas emissions linked to the production of electricity.

"LED lights will also improve airfield safety by reducing the threat of runway incursions. Airfield stop bars are made of a row of red lights across the taxiway, and the thermal inertia of the filament in a halogen lamp means that there is a delay of about half a second between being activated by an ATC controller and coming on. LED lights have an immediate response."

In the last year ADB and it's US sister company, SAS, have sold more than 3,000 LED lights to airports across the world. Brussels International Airport, with an order for 100 lights, was its first customer in February 2003. Other clients include Vancouver (60 lights), Elmendorf Air Force Base (850), Monterey Peninsula Airport (420) and Mexico's Chihahua Airport (100). Its product range to date includes taxiway centerline and stop bars inset lights and elevated taxiway edge lighting.

Thorn Airfield Lighting's Pairs based marketing & technical manager, Stephane Dardeau, agrees that LED will blaze the way in the future.

"LED lights are an attractive proposition to airports as they will help improve security and operational efficiency and ultimately increase a gateway's profits as less maintenance means a reduction in maintenance vehicles on the taxiways, reduced manpower costs and increased usage of the airfield."

"We estimate that LED lights will offer the end user a saving of around 40% over 10 years with a pay-back period of four to five years compared to traditional lamp."

Thorn was the first company to exhibit both elevated (ELD) and in pavement (ILD) taxiway LED lights at inter airport Europe two years ago, and now offers a complete range of taxiway lights for CATII/III operations.

But it is not all plain sailing for LED as LED lights are not yet usable on runways due to brightness problems, which may take another five to ten years to research and development to solve. Today's LED lights meet the 200 candelas level required or the taxiway and stop bar applications but fall way short of the thousands of candelas needed for runway and approach lights.

Incompatibility with existing infrastructure-LED requires different voltage levels to ensure the same brightness and colour as halogen lights-has also proven obstacles to the widespread uptake of the new technology.

And LED lights are significantly more expensive to install than their halogen counterparts due to the necessary electronic power module and the actual price of light emitting diodes. Reduced operating costs should, however, guarantee that the extra investment is recouped within a few years.

Carmanah has bi-passed the power compatibility problems for taxiway edge lighting by developing its own solar-powered LED lights- and enjoyed major success in selling them to the US armed forces.

It has also introduced its technology to the commercial and general airport sector with recent installations at Chicago O'Hare, Toronto Pearson and Milan Malpensa. Although the take-up of its airfield lighting solution has not been as quick at commercial airports as it has been at military installations, this could soon change if the FAA is impressed by the performance of its taxiway edge lights during test being carried out in New Jersey this winter. The US Government is looking to upgrade the lighting guidelines for the nation's general aviation gateway and is specifically seeking effective, low-cost alternatives to toady's conventional powered technology. Its products are designed to be maintenance free for five to eight years, and without the need for wiring, cabling or power they are cheaper to install than both conventional lights and their electricity powered LED rivals. "Our lights are typically one-tenth of the cost of traditional powered airfield lights," claims Carmanah business development manager, Allister Wilmott. "We recently provided a quote to light an entire runway at a US Air force base in California for $100,000- the comparable quote for a hardwired system was $2 million."

Wilmott's division has made in excess of C$1.7 million from solar LED lighting sales in 2003, taking the total number of it's units in use at airports across the globe to 4,000 in 25 countries. Over 3,500 of the total are installed at 28 US Army and Air Force bases worldwide.

Says Wilmott: "LEDs are much more efficient than traditional incandescent airfield lighting, especially when combined with solar power as both technologies are literally perfect for each other. Carmanah's end products are low voltage devices with a 95% efficiency rate of energy received to energy produced. Our lights are also extremely durable and shock resistance. In fact, a fuel truck at Sustainer Army Air Base (Iraq) recently ran over one of our taxiway lights and it still worked after being dug up out of the dirt."

Solar powered lights are, however, unlikely to ever prove a solution for center line insert lights as cabling would almost certainly be required to provide them with sufficient power to do the job and the technology to adjust their brightness or turn them on or off at will, without the use of a timer, does not yet exist.

Adds ADB's Urbaing: "No airport has yet to fully replace its taxiway lights with LED fixtures as for most of them, LED technology is still very much in the testing phase and an investment too far at this stage. Our feeling is that once the technology is accepted, sales will strongly increase in the future. Remember what happened 20 years ago with the CD."