Why the Vikings buried their GSE a long time ago

Airports are caught in the middle of opposite dynamics: growing global demand for capacity, profits and reducing the carbon footprint of operations. Combibox Systems of Sweden, the pioneer of in-ground support systems present the benefits of its in-ground support concept as a way to progress.

The in-gound approach

The in-ground approach to ground support technologies is actually not a new concept. In Sweden, Denmark and Norway this is already a common approach since well over 20 years.

The concept promotes the idea of service pits in the apron close to the aircraft service connection points. The services include the essential media that a parked aircraft needs on turnaround. This is 400Hz Ground Power, Pre Conditioned Air for cooling and heating, Potable Water and Discharge of Lavatory Water and Jet Fuel. This is supplied to the service pits by means of underground cables, tubes and ducts connecting the pits to the generating units. The concepts allows for a clean apron relieved from cable clutter and mobile equipment and immediate point-of-use availability.

We at Combibox argue that this is the most efficient and environmentally friendly way and the future for ground support. The benefits are environmental, efficiency, financial and safety.

Although the concept has been installed not only in Scandinavia but worldwide since the early 80-ties a relatively small percentage of airports worldwide have opted for this solution. We believe this is due to a number of reasons. It is only in recent years that the high oil price and environmental concern has become an immediate priority. But also due to historical lack of environmental focus on the carbon footprint of operations. For an airport it also means an infrastructure investment and project whereas mobile equipment is not at a first hand view. However the maintenance and coordination of mobile equipment in and around the gate area has infrastructure implications in operations.

Congestion

A quick look at the Boeing planning manual for ground support activities it is easy to envisage why the gate area is a highly active environment and why reducing the number of vehicles is beneficial.

The in-ground concept has not yet been internalised sakes for one of the support media namely jet fuel. Today it would hardly be anyone contending the fact that fuel hydrants is the way to provide jet fuel to an aircraft at a busy airport. The thought of dispatching a large tanker truck bringing the fuel on the apron alongside the aircraft is immediately recognized as not so efficient and risky.

Now apparently this is not yet so natural to see the same for ground power, preconditioned air, potable water and waste water. But the same argument can easily apply here.

Mobile equipment has its natural place on an airport for flexibility reasons and also for smaller airports with less traffic. But even in these cases we argue that over time the advantages of in-ground systems exceed those of mobile equipment as the primary source of ground support.

An example

The in-ground concept can replace diesel powered GPUs or use of the aircrafts own APU(Auxiliary Power Unit) for production of power and cooling. 1 kg of fuel is known to produce 3.16 kg of CO2.
 
If an aircraft parked at gate uses only the APU(Jet fuel driven power generator) for the complete turn around this results in yearly emissions of 520 tons of CO2 for just one gate. Using diesel powered GSE is better but still generates some 90 tons of CO2 yearly for just one gate and for the supply of ground power alone.

Now to reduce these emissions Airports could reduce fuel burn by using direct electricity connected to service pits. This still involves some indirect impact on the environment but is substantially lower. According to the European Parliament Technology Assessment the carbon footprint of using electricity is 300g per kWh. Using direct electricity with an in-ground system reduces the equivalent environmental impact to 32 tons per year and gate according to a study by Combibox. These 32 tons are needless to say not emitted at the airport since the power comes off the grid and can be managed.

Same results can be shown for potable water and waste water which is most commonly supplied with the use of trucks out on the apron often running idle on diesel while servicing the aircraft. This implies tons of CO2 emissions and inefficient use of manpower while also introducing more trucks into the gate area on every turnaround.

We argue that the fixed installation of an in-ground system using service pits is the natural prolongation of the "green flight" starting with minimizing jet fuel consumption in the air, flight planning and holding pattern minimizing. Then taxiing on one engine to the gate. At the gate the turnaround is then provided by an in-ground system minimizing the carbon footprint while parked for turnaround.