30 May 2005


At Gardermoen, one of the largest groundwater reservoirs in Norway is located. This aquifer is
used for both heating and cooling of Gardermoen Airport. In the summer, ground water is pumped
from cold wells and used for cooling before it is returned to the warm wells. In winter, this process is
turned around, as ground water from the warm wells is used as heat source for the heat pump.
The heat pump is mainly designed for cooling, and the design cooling demand is 9 MW. The
district cooling water is pre-cooled by the ground water, and post cooled by the combined heat
pump/refrigeration plant. The base heat load is covered by the heat pump. Additional heat is supplied
from a heat energy central with biofuels as well as oil heated and electrically heated boilers.
During the last years, heat production from the heat pump was about 11 GWh/year, and the heat
pump also provides about 8 GWh/year of the cooling demand. In addition, approximately 3 GWh/year
cold is produced by direct heat exchange with ground water. Compared with a district heating system
heated by fossil fuels, and a conventional refrigeration system for district cooling, the pay back period
for the aquifer heat pump system is within a couple of years.