Fuel for thought

posted on 22nd June 2018

Keith Mwanalushi outlines the latest advances in fuel cell technologies for ground support equipment

Emerging fuel cell technologies are being tested to demonstrate their effectiveness with GSE. However, these new technologies also come with new challenges.

Recent findings from experimental projects at airports in Hamburg and Montreal have revealed some significant advances. The GSE industry has been exploring hydrogen fuel cell technology as an alternative to diesel or gasoline power for GSE for some time, with significant progress.

The task of the fuel cell is to convert the energy contained in the hydrogen within the framework of an electrochemical process. Hydrogen and air are converted into water, resulting in the production of electrical energy, which is then used to power the vehicle.  Apart from the residual steam, this procedure is completely emission-free.

Air Liquide, a French company and supplier of industrial gases undertook a project called H2 Port at Montreal’s Pierre Elliot Trudeau International Airport. Pierre Gauthier, sales director for Air Liquide, managed the Montreal airport project.

“The project was about providing assurance to the airport operators and the OEMs that hydrogen could become viable – the project went well, it lasted for three years and a number of equipment was tested. The main targets were airport buses, luggage tractors, and the utility vehicles used by employees to get from one point to another.”

Gauthier says feedback from the airport revealed that even electric GSE were causing some problems. “In winter, electric vehicles don’t work very well so they were looking at hydrogen as a potential solution.”

As part of the project, the engines of existing conventional baggage tractors were replaced with hydrogen-fuelled internal combustion engines. Air Liquide had to look critically at the engineering aspect, location of a fuelling station, modifications of airport vehicles with the OEMs and also increasing insurance concerns.

A similar project took place at Hamburg Airport between 2007 and 2011, where two fuel cell-based baggage tractors and an apron car used hydrogen in an internal combustion engine. To secure the fuel supply for those vehicles, a hydrogen filling station was designed and constructed especially for this project.

“During this testing period, which lasted more than three years, highly valuable experiences and knowledge on practical aspects pertaining to the deployment of fuel cell based equipment were collected,” notes Michael Eggenschwiler, CEO of Hamburg Airport. “The project led to very positive results, although a few technical problems needed to be solved during this project.” As a result of the tests, Hamburg Airport deployed new baggage tugs with new breed fuel cells from May 2012, according to Eggenschwiler.

The R 07-25 tractors, manufactured by STILL, were used in the Hamburg project. The two tow tractors are mainly used for hauling luggage to and from the aircraft. According to the environmental team at Hamburg Airport, they offered the most ideal conditions for changing over to hydrogen propulsion. The fuel cells were installed in the space that normally holds the traction battery.

The specifications concerning the changeover were stringent because decreases in efficiency or functional limitations as a result of modified dimensions or ground clearance were not permissible. Furthermore, the mode of operation would have to be identical with that of the conventional tractor.

An immediate issue that presented itself to the Hamburg environmental team, as with their counterparts in Montreal, was that of storage. There is an issue of how to conveniently store hydrogen at airports, considering that it’s not as dense as other fuels. Eggenschwiler points to two aspects to consider: hydrogen storage in the deployed vehicle and hydrogen storage at the fuelling facility provided by the airport.

“In vehicles, the hydrogen is stored highly compressed (200 bar). According to our experiences, this seems to be the suitable way of storing hydrogen in heavy duty vehicles. However, a further increase in storing pressure is intended to extend the range of our hydrogen-powered vehicles,” says Eggenschwiler.

With hydrogen storage in fuel farms or similar facilities, Eggenschwiler warns of possible hydrogen losses due to boil offs. “When using cryogenic tank systems, similar problems can arise. To avoid losses from boil offs, without losing storage capacity, storage systems based on low or medium pressure technology are deployed.”

Pierre Gauthier adds that similar concerns were found at the Montreal project, particularly from an insurance perspective. “The insurance companies were concerned about the amount of hydrogen that would be contained in these facilities and what would happen if a sudden release of hydrogen were to take place; let’s say underneath the airport, close to the aircraft or other vehicles that were carrying gasoline diesel or jet fuel.”

Gauthier admits that more work needs to be done in ensuring that the risks associated with hydrogen storage are minimised. However, he explains that as long as hydrogen is stored in vehicles that are used outside the airport perimeter, it did not present an issue for insurance companies or authorities.

“It’s when the hydrogen is stored in vehicles that go inside the airport property, such as the baggage drop-off areas – this is when the insurance companies get concerned; we need to do some more work with the risk mitigation,” says Gauthier.

Another obstacle is that fuel cell technology requires a finer, higher laboratory grade of hydrogen than internal combustion technology but Michael Eggenschwiler says the next generation of fuel cell systems will no longer require highly purified hydrogen. “From our perspective, this is also the right way to reduce production or procurement costs of hydrogen.”

Gauthier says this issue has now been resolved. “The issue was related to hydrogen produced that would have a high cell content or high sulphur content and most of the sources now producing hydrogen worldwide are getting rid of the cell or sulphur molecules in their hydrogen process.”

He adds that industrial hydrogen is now at levels where the fuel cell will take that hydrogen and utilise it in a way that will provide the guarantees required by OEMs. “Industrial hydrogen quality, as we know it today, is not an issue. It has reached a level where the product is of the right quality.”

JBT AeroTech developed a prototype GSE back in 2006. The JBT CPT-7 electric transporter was operated by Iberia Airlines in Madrid. BESEL supplied the hydrogen fuel cell system, Air Liquide supplied the hydrogen and JBT did the assembly and testing. According to JBT, the unit was built, tested and worked as intended but in 2007, Iberia decided not to pursue the project further.

Gauthier believes the next step is for such technology to be at the right price and for the OEMs to see the right opportunity to introduce the equipment. “The airport operators are waiting for hydrogen technology to be priced at a level that will make for a more attractive business case, so it’s still a few years from now.”

Last year, JBT teamed up with InnovaTech and Enerfuel to develop a Fuel Cell Range Extender (FCRE) for battery-powered GSE. The technology takes a bio-diesel fuel and runs it through a converter that turns it into hydrogen that feeds into a fuel cell. The cell, in turn, animates the GSE through electric power.

“Our co-operation with InnovaTek is part of a longer-term project that we hope will lower barriers to the introduction of electric-powered equipment,” says Nick Heemskerk, JBT AeroTech’s global product development manager.

Heemskerk indicates that one of these barriers is the need for battery chargers. At many airports, the electric grid is not prepared to support electric charging, and expanding the grid can be very expensive and disruptive to operations. Real estate at airports is at a premium, and it is sometimes difficult to find places to put chargers and park the equipment while it is charging.

The FCRE is essentially an on-board trickle charger that keeps the batteries of JBT’s Commander 15i electric loader topped off, and eliminates the need for facility chargers. “The device generates hydrogen from a variety of fuels, in our case a bio jet fuel. The hydrogen is fed into a fuel cell which generates electricity, which is used to charge the battery. The overall process is cleaner and more efficient than a diesel engine, but runs on easily stored and distributed liquid fuels,” says Heemskerk. The project was in part funded by a United States Department of Transport (DOT) grant.

Bio jet fuel is readily available today and can be converted chemically into hydrogen fuel. Bio-fuels have proven their green credentials but at what cost? Unrelated tests from similar trials in Amsterdam showed that putting bio-fuel in GSE in the current environment is about twice as expensive as the cost of traditional fuels.

Experts believe that this remains an issue and commercial viability is still going to be a challenge, that’s one reason why the DOT awarded the grant for the FCRE project in a bid to prove the concept.

“Phase one has been successful,” according to JBT’s Heemskerk. “InnovaTek has submitted a proposal for phase two, which includes testing a prototype in an airport environment; however, commercial applications are still several years away.”