The aviation industry has entered an era where conservation is the topmost priority. Faced with increasing competition and environmental regulations, rising fuel costs and financial constraints, industry executives are doing everything possible to streamline their operations. While engineers are doing their utmost to reduce fuel consumption and reduce emissions on the aircraft, there are ways we can also achieve those reductions on the ramp-site, utilizing alternative fuel vehicles.
One type of alternative fuel vehicle is an electric vehicle. The concept of electric vehicles is not new. In fact, the first crude electric carriage was being invented as early as 1832*. The concept was refined and batteries improved, causing electric vehicles to flourish for the next hundred years. In the early 1920s, advancements in production and the inexpensive availability of fossil fuels caused vehicles using the combustion engine to overtake electric vehicles. By 1935 electric vehicles had all but disappeared.
In the 1970s electric vehicles began making a comeback, yet many early electric vehicles drew criticism and skeptics because they were not designed originally as electric vehicles. Those vehicles were actually converted, based on combustion engine components, and were not necessarily the most efficient in the form of amp draw and usage. Consequently, many early adopters of the technology may have already disqualified it for practical applications.
In the past 60 years, however, we have seen the advancement in battery life, battery capacity, the sophistication of the charger, the control systems, and a reduction in amp draw per hour, therefore increasing the overall endurance per charge. Technology has included things like onboard diagnostics, so should an electric vehicle fail, the controller - -everything runs through the controller -- can tell you what part has failed; whether it is a switch or a wire. Reliability has significantly improved over the years.
Electric vehicles have proven to be extremely efficient as aircraft tractors in that their utilization over a 24 - hour period of time is actually fairly minimal. Meaning that unlike a baggage tractor which may be running nearly non-stop, the aircraft towing tractor is utilized mainly during pushback or maintenance towing, typically a maximum of two to three hours of continuous operation per day. Consequently, the existing lead-acid battery technology has worked quite well and has not required any significant advancements in that technology to successfully handle the current FBO, regional airlines, trunk airlines, or corporate applications. Vehicles are able to operate on a single charge for an entire day, being recharged at night when operations are at a minimum. The current lead-acid battery, because of its design parameters, not only achieves the daily operation but also has a significant life endurance of anywhere from six to 15 years depending upon application and maintenance.
Looking to the future, there is some trend toward rapid charging, which utilizes a more sophisticated charging system. Ranging in price from $30,000 to approximately $200,000, these rapid charge systems allow for batteries to be recharged quicker than the normal six to eight hours of conventional charging. Additionally, these units are also capable of charging a variety of voltages and a variety of vehicles at one time. The rapid charging alternative is more geared towards the baggage tractors and vehicles with smaller capacity batteries that cannot operate on a full-day shift. It is claimed that quick charges will go to 80% in 30 minutes, and then every so often they need to be “top charged.” Since we have been utilizing quick charge equipment only about three years, their overall impact on the life of the battery has yet to be proven.
Another area of research is hydrogen fuel cells. As early as 2003, President Bush was stating the technology of hydrogen fuel cells “...can make a fundamental difference for the future of our children.” (whitehouse.gov/news/releases/2003/02/20030206-12.html) Pricing and technology have not yet enabled the airlines or airline industry to feasibly use this technology yet. There is a company, Concurrent Technologies Corporation out of Pennsylvania (CTC.com) that is attempting to put a fuel cell in a tug that has the capability of practically running an entire airport!
One of the reasons that electric vehicles have been unsuccessful in the automobile arena is the lack of distance and speed the vehicle can travel between charges. In-town commuter driving may work, however, in the U. S. many of us live significant distances away from our workplace. Consequently that distance has been a detriment for the electric success in automobiles. Lately we are seeing a trend in hybrids which may be the solution to that requirement. Hybrids, however, would not probably function well for ground support vehicles. Part of that is due to cost. You have reduced the emissions, which have been stated as a goal, but you have a small vehicle which needs an electric motor and a gasoline engine so you have added to the weight and the complexity of the vehicle. If you can remain all electric it certainly simplifies the vehicle. An all-electric vehicle requires no oil, no tune-ups, no starters or transmissions. You have an armature, some brushes and some fields -- it is all done magnetically through a generator -- there is very little to do on an electric motor: Therefore your maintenance costs are less.
While thinking about weight of the vehicles, one benefit is the ability to utilize the heavy weight of a lead-acid battery versus some equipment such as automobiles where they are trying to incorporate lighter materials. You can only transport so much weight. If a car or pickup has all of its payload capacity absorbed in carrying the battery then you can’t haul people or baggage or anything else. Conversely, we need the weight to do our jobs.
Yet, baggage tractors do not require the weight of the lead-acid. Batteries of a different type of material would work in that application. All these vehicles need is enough battery capacity to do their job OR to be able to be quick charged, or charged quickly enough that they can be put back into service without impacting the flow of the airport.
Another factor that has limited electric vehicle usage at airports has been the availability of power for recharging purposes at the gates. Again, the airport or the airline may have enough power to operate or recharge some vehicles, but to recharge an entire fleet of vehicles does present a logistics challenge. This has been somewhat negated by the rapid charge systems, which turn vehicles more quickly through the charging process, therefore reducing the amount of long-term parking for long-term recharging on a daily basis.
It has been proven that electric vehicles cost significantly less to operate but they do have a higher initial purchase price. The challenge to electric vehicle manufacturers is to produce a vehicle that is within proximity of the price of combustion engine vehicles so that during these financially- challenging times that the airline industry is facing - in some cases they are not able to look long - term; electric vehicles make sense to purchase. Airlines need to resolve their needs now and cash is king.
It is our opinion that most ground support vehicles can be electrified since they pretty much operate in a small area and their daily use is fairly limited. Belt loaders, fuel trucks and even baggage tractors would be good applications for electric vehicles, and with the rapid charge advancements it is fairly certain that these groupings of ground support equipment will be electrified in the not too distant future. This should produce a significant reduction in emissions as well as reduce the use of fossil fuels at airports throughout the world. What percentage of emissions these airport vehicles contribute to the overall environment quality may be debated, however, every area that we as consumers can use to decrease emissions and fuel consumption has got to help.
