EVs are not just for the road
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 and luggage movement, towing carts around. The same applies to small people carriers, ferrying people with 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.
EV deployment expanding to external areas to meet needs of greener airports
The operation of EVs makes sense, and is required, in enclosed spaces in which there are large numbers of people, as is the case in airport terminals. Emissions here 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 very wide, embracing the use of LEDs for more energy-efficient ground lighting (see article in December 2011 e-tech), the provision of green energy supply in terminal halls, geothermal cooling to heat and cool parked aircraft and the future phasing out of diesel engines for all airport ground support equipment (GSE). This last measure entails the introduction of a wide range of electric vehicles and ancillary equipment to support airport operations.
Ubiquitous electric-powered equipment
GSE is central to airport operations everywhere. Operations making 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, which include personal buggies, buses, self-propelled stairs, boarding bridges and belt loaders.
The same goes for equipment such as the catering trucks needed to supply aircraft with food and drinks, or even lavatory services vehicles. Airports also operate fleets of small cars for a variety of ground operations, such as inspecting runways for the presence of debris that may be potentially dangerous for aircraft, or 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.
Preparing for takeoff!
After landing, aircraft taxi to their allocated gates using power from their engines. However, when the time comes to depart, aircraft have to be pushed back from their gates by low-profile tractors, some using towbars, putting them into a position from which they can taxi using power from their own engines.
Until now pushback tractors have been powered predominantly by ICEs; however a new generation of tractors uses hybrid or electric propulsion, 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 Li-ion battery system to ensure it never becomes fully discharged.
A recent example of electric-powered tractor is provided by Mototok, a German company which has introduced a series of compact towbarless electric wireless remote-controlled aircraft tugs, the largest of which can manoeuvre aircraft of up to 195 tonnes.
Significant fuel savings can still be achieved
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 (IAI) to tow aircraft between gates and runway with the aircraft’s engines turned off.
Another 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, using 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 unnecessary 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 systems that may not be as visible, but are nevertheless essential. They include machines and systems that do not pose explosion risks, an essential feature when operating alongside jet fuel, and equipment that can be protected against ingress of water or foreign parts. IEC TC 31: Equipment for explosive atmospheres, and TC 70: Degrees of protection provided by enclosures, prepare International Standards for such equipment. Long derided for their large fuel consumption and excessive "carbon footprint", civil and military aviation have made significant progress in reducing these negative issues through the wider adoption of electrical equipment and vehicles across all their ground operations. A lot is being done to make the air transport industry more sustainable.