As pressure for more environmentally friendly aviation increases – from customers, regulators and within the industry itself – pre-conditioned air units (PCAs) are becoming an ever-more worthwhile investment. Megan Ramsay reports
PCAs are used at airports to attain and maintain a suitable temperature within an aircraft while it is parked, supplying hot or cold air into the cabin for the comfort of passengers on board. They run off electricity, making them a cheaper and more sustainable option than the aircraft’s own auxiliary power unit (APU), which is costly in terms of fuel and generates far more CO2 emissions.
One producer of PCAs is Spanish company ADELTE. Marketing director François Mamert says the importance of this piece of equipment is threefold. “First, it allows airlines to reduce their costs – the fee paid to the airport is much less expensive than the cost of fuel consumption while stationed and the maintenance of the APU. Second, airports can use them to generate extra revenue by charging airlines to use them. And third, there is a big tendency to create greener airports that generate less CO2; PCAs are a good tool for that.”
Indeed, he notes that Airports Council International (ACI), the International Civil Aviation Organization (ICAO) and other organisations are “really pushing” for airports to lower their CO2 (and other) emissions and that PCAs contribute to achieving this objective.
He explains: “Airports are interested in reducing their carbon footprint. They are responsible for the global pollution (CO2 is only one, though the most significant, of those pollutants) generated by the overall activity throughout the LTO cycle –which is between the moment the aircraft is on approach to land to the moment of its take-off, including ground activities during turnaround.
“Although all emissions must be taken into account, including those of the ground support equipment, the vehicular traffic inside but also to/from the airport, and the terminal building itself (air conditioning, central heating, etc), the aircraft itself is a significant factor. When a PCA service is not available on the stand where the aircraft is stationed, the pilots have no choice but to run the APU to provide air conditioning to the cabin and this generates a tremendous amount of CO2.”
For example, he estimates that an aircraft of the size of an A320 or B737 will consume around 100kg of jet fuel per hour. When it combines with the air during combustion, this generates more than 300kg of C02. Considering a single aircraft stand occupied for nine hours per day, running the APU will generate more than 1,000 tons of CO2 in a year. “This is the same as 2,000 cars driving from Barcelona to Berlin … and back!” he observes – and widebody aircraft would obviously generate much more CO2.
Just recently, on 6 October, ACI and ICAO signed an MoU for providing a framework for enhanced co-operation on environmental initiatives, including information exchange, best practice guidance, workshops and training.
Angela Gittens, director general of ACI World, points out: “Environmental protection is one of ICAO’s strategic objectives, while promoting airport excellence and building capacity in ACI World and Regions are both within ACI’s strategic objectives. Our respective goals align with the need to improve environment-related initiatives and promote the respective capacity building at airports worldwide.”
The purpose of a PCA is to provide an efficient, flexible and reliable way to deliver high-quality pre-conditioned air for cooling or heating to a variety of parked aircraft. When it comes to deciding which PCAs to install, the main criteria to take into account are the type and size of the aircraft operating to/from the airport in question, and its location’s climatic conditions – both the ambient air temperature and relative humidity.
Mamert explains further: “For regions with extreme weather conditions, the refrigerant used as a default, R-410A, must be replaced by R-134a. Both these gases, being near-azeotropic, enable simple top-up recharge in case of a leak – unlike other gases such as R-407 which, being a ternary blend, requires complete removal and disposal prior to a complete recharge or the system progressively loses performance.”
He continues: “PCAs are point-of-use units which can fit any layout platform and can be installed on any modern passenger boarding bridge (PBB). The largest PCAs can weigh over 4,000kg, which is far from negligible, but PBBs are now designed to support this extra weight. There are two configurations available: the PCA can be either hung underneath the PBB for direct supply to the aircraft via a flexible hose, or installed on the ground near the aircraft’s stop position. In the latter case, the distribution can be achieved in various forms – from laying the hose directly on the ground, to a telescopic tube under the PBB or even an underground duct to a service pit in which the flexible hose is housed.”
Availability of electricity is, of course, a factor for any airport considering the use of PCAs, although Mamert is keen to point out that ADELTE’s PCAs are highly efficient.
The design and operational characteristics of PCAs are codified and regulated, he adds. Manufacturers refer to EN 12312-17, which is the main standard for air conditioning equipment, as well as to the International Air Transport Association’s AHM 910, AHM 913, AHM 974 and AHM 1002, as well as requirements defined by the various aircraft manufacturers. In addition, there are defined protocols that operators must follow in order to operate and properly maintain the equipment.
The most commonly used PCAs used at airports today have a rather binary operating system: they are basically either on or off. This means that the system is always operating at 100% of its capacity regardless of the actual aircraft needs such as those relating to the passenger load and outside air temperature. The result is a significant waste of energy.
While some PCA units available on the market today can vary their cooling capacity, this is possible to only a limited extent.
On the other hand, Mamert states: “ADELTE has developed a new technology, called full inverter, offering a full regulation of the PCA’s capacity using specific four-phase compressors and a high-quality direct drive centrifugal blower (VFD). This enables us to make a fine and constant regulation in coherence with the aircraft’s cabin temperature real needs. It directly benefits our customers by dramatically reducing the electrical consumption and increasing efficiency by up to 35%.”
Even more dramatic, he claims, is the reduction of electrical energy when the system is operating in cooling mode. The ADELTE inverter will then operate as a heat pump, mining energy from the ambient air to produce the required heat. Competing products use conventional heating resistors of 30–70kW.
Mamert remarks: “Developing this inverter technology was not easy to do. Also, previously there was not so much attention on CO2 emissions. The context now is that we are all more focused on these issues and airports are very interested.”
AENA is the first airport operator to have purchased this technology, which was introduced in 2015. The Spanish airport operator ordered 20 ground-mounted Zephir units with full inverter technology in March last year, for installation at Palma de Mallorca airport. The deal included 10 100kW units, six 140kW units and four 240kW units, with deliveries having begun last summer.
Jordi Floreta, vice-president and commercial director at ADELTE, comments: “Constant dedication to R&D&I (research, development and innovation) is crucial for providing better service and delivering the most advanced gate solutions to clients around the world. With this totally new inverter technology, ADELTE is definitely pushing the GSE sector to the next level and accelerating the process towards green airports.”
Of course, it is important to note that the upfront cost (capital expenditure) of a PCA unit is not the sole criterion in selecting the most suitable equipment for an airport. Operational expenditure, which includes (among other items) consumption of electricity, maintenance and replacement parts (a compressor designed for fixed operation will age badly when one forces it to vary, Mamert observes) can all add up over the lifetime of the equipment.
Looking to the future, Mamert says: “More and more airports require an advanced system called IASS (integrated aircraft stand system). The IASS provides better integration between the PCA and other stand equipment such as PBB, VDGS (visual docking guidance system), and GPU (ground power unit), and allows the airport to monitor incidents and the number of service hours of each piece of equipment. It provides useful information in order to have a global understanding of gate equipment operation and in planning of preventive maintenance. We are currently installing that solution in our ongoing projects at Karachi and Islamabad in Pakistan,” he reveals.
Globally, Mamert believes the demand for PCA units is increasing in most markets, supported by the increase in airline traffic, the expansion of existing terminals, the construction of new airports, sustainability policies, the need for airports to generate new revenues and for airlines to lower their operating costs while providing comfort to their passengers.
“We have won the confidence of customers from around the world. We are proud to list customers from as far away as Seoul in South Korea to Europe, the Middle East and Latin America. The context is favourable for the consolidation of demand for PCAs using inverter technology,” he concludes.
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