Electric vehicles (EVs) can be found in a growing number of industrial environments. In civilian and military aerodromes, they are found both indoors and outdoors. Together with a range of ancillary equipment, they are set to play a larger role in meeting environmental directives.

For most people, mention of EVs brings to mind electric cars of the hybrid or fully electric kind – both types can be seen on roads and are being widely reported in the media.

Other EVs are far less visible to the public but are found in other transport-related activities, particularly in airport operations. Many of the vehicles and much of the other equipment used in airport environments are being converted to electric power.

EVs have been used in airports for a long time. Small electric tow tractors are a familiar sight inside airport terminals where they are used for baggage collection, luggage movement and towing carts around. The same applies to small-scale people carriers, which ferry people who have reduced mobility to boarding gates.

Electric service vehicles are also essential in airports for transporting loads to shops, bars or other services, for moving rows of luggage trolleys and for cleaning floors or collecting refuse.

Uses Outside the Terminal

The operation of EVs makes sense, and is required, in enclosed spaces in which there are large numbers of people, as seen in airport terminals. Emissions from internal combustion engines (ICEs) would represent health hazards. However, larger EVs are also increasingly used in airports' external areas for a growing range of tasks.

The move is accelerated by national and international initiatives and directives aimed at greening airport operations. The scope is wide and includes embracing the use of LEDs for more energy-efficient ground lighting, providing green energy supply in terminal halls, adopting geothermal cooling to heat and cool parked aircraft and the future phasing out of diesel engines for airport ground support equipment (GSE). This last measure entails introducing a wide range of electric vehicles and ancillary equipment to support airport operations.

GSE is central to airport operations everywhere. Operations that make life easier for passengers (allowing them to move from/to terminals and aircraft, to board/disembark and to load/unload their luggage or cargo) rely increasingly on partially or fully electrically powered equipment. This includes personal buggies, buses, self-propelled stairs, boarding bridges and belt loaders.

The same trend toward electrification can be found in equipment such as the catering trucks that supply aircraft with food and drinks and even aircraft lavatory services vehicles.

Airports also operate fleets of cars for a variety of ground operations, such as inspecting runways for debris that may be dangerous for aircraft or for moving personnel around. Many airports adopt EVs for these tasks.

All EVs, small and large, rely on international standards prepared, in particular, by IEC Technical Committee (TC) 69: Electric road vehicles and electric industrial trucks, as well as by TC 21: Secondary cells and batteries, and Subcommittee (SC) 23H: Plugs, socket-outlets and couplers for industrial and similar applications, and for electric vehicles.

Set for Takeoff

Arriving aircraft taxi to their allocated gates using power from their engines. However, when the time comes to depart the gate and taxi for takeoff, aircraft have to be pushed back from their gates. This work is done by low-profile tractors, which use towbars to move the aircraft into a position from which they can taxi under their own power.

Until now, pushback tractors have been powered predominantly by internal combustion engines. However, a new generation of tractors uses hybrid or electric propulsion making this a growing trend in the sector.

Lufthansa is currently testing a hybrid tractor the Kalmar Motor AB TBL 800 eSchlepper, which was designed specifically for wide-bodied aircraft. This tractor is equipped with a diesel engine that is expected to run less than 30% of the time and only to charge the lithium-ion battery system to ensure it never becomes fully discharged.

Another recent example of this type of machine is provided by Mototok, a German company that introduced a series of compact towbarless electric wireless remote-controlled aircraft tugs. The largest can maneuver aircraft of up to 195 tonnes.

Driving Towards Greater Fuel Savings

Having been pushed back and turned around by tugs, aircraft still have to taxi under their own power all the way from aprons to the runway for takeoff.

The whole procedure can burn a significant amount of fuel, particularly if there is airport congestion. The industry is looking for solutions to reduce unnecessary fuel burn and expenses from aircraft moving to takeoff positions using their own engines.

One solution already deployed is Taxibot, a hybrid-electric aircraft tractor developed by Israel Aerospace Industries Ltd to tow aircraft between gates and runway with the aircraft’s engines turned off.

(Watch a video of Taxibot’s tests with Lufthansa at Frankfort.)

EGTS allows aircraft to taxi and pushback without requiring the use of aircraft engines. Image source: EGTSEGTS allows aircraft to taxi and pushback without requiring the use of aircraft engines. Image source: EGTSAnother ground-breaking solution, slated to enter service in 2016, is the Electric Green Taxiing System (EGTS) developed jointly by Honeywell and Safran, which allows aircraft to taxi without employing their jet engines. The system uses electric motors to drive the main landing gear wheels.

EGTS International notes that "taxi operations represent a significant portion of short haul airline fuel costs – on average 4% of fleet fuel consumption for short-haul airlines operating single-aisle aircraft from congested airports.” Since fuel costs account for between 30-40% of direct operating costs, using EGTS would help airlines save millions of dollars every year on taxiing fuel burn.

However, this system wouldn't be suitable for aircraft flying medium- and long-haul routes as its extra weight would result in higher fuel consumption that would more than offset savings made on the ground.

Many More Systems

In addition to the wide range of specialist vehicles and equipment, airports are equipped with facilities that may not be as visible, but are nevertheless essential. These include machines and systems that do not pose explosion risks, an essential feature when operating alongside jet fuel. IEC TC 31: Equipment for explosive atmospheres, which prepares the IEC 60079 series of standards for this type of equipment, and IECEx, the IEC system for certification to Standards relating to equipment for use in explosive atmospheres, ensure GSE is safe to be used in potentially hazardous environments, and that staff that operate and service it are qualified and certified.

Protected sensitive equipment from the adverse effect of water, dust or other matters is also very important in harsh environments, such as airports. IEC TC 70: Degrees of protection provided by enclosures, developed IEC 60529, which developed the well-known IP code, that defines the degrees of protection against ingress of water or foreign parts, and IEC 62262, which concerns the "degrees of protection provided by enclosures for electrical equipment against external mechanical impacts (IK code)".

Long derided for their fuel consumption and carbon footprint, civil and military aviation have made significant progress in reducing these negative attributes through the wider adoption of electrical equipment and electric vehicles across all their ground operations.

To contact the author of this article, email engineering360editors@ihs.com