We've heard the old chestnut that there's nothing new within the GSE world more often than not. The truth is there always something new to discuss about the future of GSE product development. Here are just a few of the advancements with heard about recently, all with a particularly energy-efficient theme:
LITHIUM
Last year, the Idaho National Laboratory, a U.S. Department of Energy research operations, pitted lithium batteries against the commonly used flooded lead-acid batteries used throughout the GSE industry.
“Validation testing previously had not been performed within fleet operations to determine if the performance of current advanced batteries is sufficient to withstand the duty cycle of electric baggage tractors,” according to the report’s introductory remarks.
A rigorous day-to-day GSE vehicles performance test was set up with Southwest Airlines’ ramp operations at Ontario International Airport. The lab used four of the airline’s baggage tractors with the help of John Salter, reliability analyst for GSE with Southwest and Tony DiLuccia, lead GSE technician for operations at ONT.
”No alterations to the fleet operations were made for the baggage tractors under test in order to allow for comparison with other GSE fleets,” the report says.
Corvus Energy Limited was chosen to supply the lithium-based battery packs used for the test. Corvus created a prototype battery pack configured with three battery modules in parallel with a junction box and vehicle control unit (VCU). Each module contained 24 series-connected cells in order to allow for a similar voltage range as currently used within the baggage tractors. The three modules and junction box were placed in a structure that was specifically designed to fit the battery cavity of an airport baggage tractor.
Two the tractors had the Corvus batteries while the other relied on flooded lead-acid batteries.
Minute-by-minute logsb of battery usage information were collected for each battery over the duration of the demonstration to gain a better understanding of how the different battery chemistries handle the duty cycle of a ground support baggage tractor. To accomplish this, the BIM needed to have a means for monitoring, recording, and communicating to the ECOtality data server. It was determined that the desired information to be communicated was cell voltages, pack voltage, pack current, and pack temperature. For the FLA battery packs, this meant that the BIM hardware would contain the proper circuitry and software to monitor and record:
- 20 high-voltage leads placed on the positive terminal of every other cell of a 40-cell, 80-volt (V) nominal pack in order to record intermediate cell voltages and full battery pack voltage.
- Pack charge and discharge current via a bus bar, connecting two battery cells and acting as a shunt.
- Battery temperature with a thermistor placed on the pack.
For the Corvus battery packs, each module was sealed without a means to connect the BIM analog circuitry to the modules. However, the Corvus BMS internal to each module communicated analog data for maximum and minimum cell voltages, module voltage, module current, module temperature, and module state-of-charge via the BMS CAN bus. Because the BIM also had to be connected to the Corvus CAN bus for charging, all analog data were taken from each module’s BMS using a secondary CAN bus on the BIM.
Since the Corvus lithium battery pack weighed in at 500 pounds, about 2,700 pounds less than the flooded acid battery, the weight difference was addressed with the addition of ballast and steel plate. Over the course of 6 months, battery usage and charging data were collected from four eGSE baggage tractors.
The results proved positive for lithium.
“The lithium battery packs can accept a full charge current for the majority of a full charge, while the FLA battery packs can only accept full charge current for approximately the first hour of a full charge,” the report says. “After the first hour, or in the case of an opportunity charge, the charge current for the FLA battery drops in order to maintain a charge voltage limitation.”
The report also pointed out that the lithium batteries required less time for charging, resulting in less charge events. The lithium batteries were able to be charged more rapidly, with essentially an equal capacity added during the charge.
As for on-the-ramp performance, the evaluation showed the lithium batteries had a more consistent discharge to charge capacity efficiency at 85 percent and 86.7 percent, compared to the FLA batteries at 60.6 percent and 87.2 percent.
“When comparing the amount of time spent driving the baggage tractors versus charging,” the report says, “there is a clear advantage to the lithium battery vehicles, with more time available for driving than required for charging. The FLA battery vehicles remained inefficient, with the vehicles undergoing more hours of charging than they could be driven due to the longer charges and battery equalization cycles required for the FLA batteries.”
The findings were good news for Gian Carlo, general manager of GTA Aviation, when we saw him earlier this year at our AviationPros LIVE trade show in Las Vegas.
“I believe this report provides a very credible source for supporting our product,” he says. “It takes some of the theory out of the use of lithium to power GSE and gives us a practical way to market the long-life practicality of the lithium batteries.
LEAD-ACID BATTERIES
We recently heard from Todd Allen, president of Allen Energy, about the new battery that a couple of airlines are currently testing on their equipment.
“We have a new battery out there called thin plate pure lead,” he told us.”They have the benefits of lithium at a lead acid price.”
While they will be new to the GSE market, the NexSys battery and charger system manufactured by EnerSys has been used in other industries.
According to product information, the batteries are constructed from 99 percent pure lead. The plates are extremely thin so more of them can fit into the battery.
“More plates means more power,” Allen adds.
Also, the batteries feature compressed Absorbed Glass Mat separator with high electrolty absortion and stability to enhance cyclic capability. To resist vibration and eliminate internal sparking, cell connectors are casted to the plates and bonded.
Taken together, Allen says NexSys batteries offer optimized cycling performance and rapid recharging that conventional lead acid batteries – gel or flooded – cannot match. When used with an approved charger, the batteries offering the following benefits:
- High energy throughput – up to 180 percent of C per 24 hours with an opportunity charging regime.
- Long maintenance-free life cycle – up to 1,200 cycles at 60 percent DOD.
- Short recharge times – less than three hours at 60 percent DOD.
- More power in less space – the batteries typically take up a third less space than the equivalent lead calcium batteries.
PRECONDITIONED AIR
Meanwhile, outside a gate at Sarasota-Bradenton International Airport, a new more environmentally friendly PCA unit is being put to test with great results, according Rick Hansen, president of the aptly named Verde GSE.
“We didn’t want to rush this product to market since we wanted to put it in a real-life environment and what we’ve heard from the airport has been very positive.
Hansen recently started the company along with three other partners, including an engineer he had worked with during his career at Hobart Ground Power Systems.
"We set out to build a different type of business to build a different type of unit," he adds. "We've incorporated the best of the refrigerant technologies from the automotive, food equipment, and aerospace industries to build a result in a simple, low cost, yet technologically advanced PCA system.
Hansen adds that the company's design principles are centered on four green principles:
- use of renewable materials,
- energy efficient products,
- quiet system operation,
- and ultra-low charge units and safer refrigerants.
Hansen put a PCA unit running at 30-ton mode at Sarasota last summer and when we spoke to him, he was making plans to test a 60-ton unit at Orlando International Airport by September.
“Having the unit at these airport has helped us understand the customer requirements better,” Hansen told us, “and we have used their feedback to make some nice improvements.”
At Sarasota, the Verde unit was matched up with a competitor’s unit and were instrumented by the airport to service an MD-80 aircraft.
“What they discovered is the competitor's unit was pulling 85 amps, and our unit was pulling 55 amps,” he adds. “Our unit was 35 percent more energy efficient. In addition our unit had 100 feet of hose between the unit and the aircraft and the competitor's unit 60 feet. So even though our unit had 40 more feet of hose, it was able to produce 10 degrees cooler air in the forward section of the aircraft and 6 degrees cooler air in the rear of the aircraft. We are very happy with these results.”
Accordingly, Hansen says the company will start actively marketing the PCA unit by October.
FUEL CELLS
Last June, Plug Power Inc. publically demonstrated its Plug Power GSE fuel cell prototype this week, for the first time.
The demonstration involved Charlatte cargo tractor, which pulled 40,000 pounds of heavy weight, which was spread equally on four dollies. This demonstration took place at Plug Power premises and the audience included Charlatte America (GSE manufacturer), FedEx Express (GSE operator and project partner) along with the executives of Plug Power and also the representatives from the Department of Energy.
We first wrote about this development in our December 2011/January 2012 issue (“Fueling GSE With Fuel Cells.”) At the time, Plug Power was the recipient of a $2.5 million, three-year grant from the Department of Energy to retrofit 15 Charlatte CTGE cargo tractors with its brand of hydrogen-powered fuel cells.
The company’s newly engineered and designed hydrogen fuel cell beta unit promises to by a zero-emission power source for GSE, including auxiliary power units, tractors and beltloaders.
Plug Power is trying to penetrate into the markets which are adjacent to the material handling and also, where the GenDrive fuel cells have already proven their worth.
The company has planned that in the next phase of this project will deliver 15 Plug Power GSE fuel cells to FedEx at Memphis Airport by the fourth quarter of 2014.
In conjunction with the GSE fuel cells, Plug Power will provide a GenFuel hydrogen infrastructure that includes:
- Scalable hydrogen supply that can ramp up from fueling 15 demo units to fueling an entire fleet of commercial units, without additional investment.
- Low cost liquid hydrogen that offers accelerated fuel savings as the number of GSE tugs in operation increases.
