The world's largest aquifer storage unit supplies energy to the airport
To cool and heat Stockholm Arlanda Airport, the world's largest aquifer storage unit is used. By utilising a natural cycle located in the nearby boulder ridge, there is an energy savings equivalent to a year's electricity use for two thousand single-family homes.
Energy use at the airport
An enormous amount of energy is consumed at an airport, especially in the Nordic countries, where energy is needed both to cool and heat the facilities. Running Stockholm Arlanda requires as much energy as a small city of 25,000 residents.
Since the summer of 2009, the aquifer storage unit at Stockholm Arlanda Airport – the largest of its kind in the world – has helped dramatically reduce energy use. Groundwater from the aquifer in the boulder ridge known as Brunkebergsåsen is used to cool facilities in the summer and heat them using the same system in the winter.
Like a giant thermos
The aquifer is a geological formation that stores groundwater with such a large capacity and permeability that the water can be used. There are a number of groundwater storage units in the Brunkebergsåsen ridge divided into hot and cold sections.
The containment rooms in the ridge are comparable to a gigantic thermos. During the summer, cold water is pumped into the airport’s district cooling network. As the water runs through the system, it is heated up, and when it returns to the aquifer storage unit it has a temperature of around 20 degrees Centigrade. The heated water is then pumped underground and used in the winter to melt snow on the aircraft parking stands and to preheat the ventilation air in buildings.
No groundwater is used in the process. Instead, the same volume is returned, pumped up through the pipes to the groundwater storage unit after it is used.
Equivalent to one hundred football pitches
The aquifer technology for recovering cooling and heating has been available for more than 25 years but had never been used before on the same scale as it has at Stockholm Arlanda Airport. It involves areas as large as one hundred football pitches.
Using the aquifer, the airport can reduce its annual energy use by 19 gigawatt-hours (GWh), which is equivalent to the energy used by 2,000 single-family homes.
By using the aquifer, large volumes of green electricity and biofuel have been freed up and can now be used by other companies. Since 2005, Stockholm Arlanda Airport only uses green electricity and since 2006 it only uses district heating from biofuel.