Lawrie Cornish, of Dunedin, asks :-
Do the various scientific bases in the Antarctic have freezers to store their food? i.e. do they actually need them?
Graeme Plank, a physicist at the University of Canterbury who responded from Scott Base when on a summer trip maintaining the atmospheric research equipment, responded.
The short answer is yes.
Over the past week the outside temperature has just risen above the normal freezing level of water, i.e. zero degrees Celsius. For food to be kept safely it must be frozen to at least -18 degrees. So the natural environment around our base in summer is too warm to store food without the aid of a freezer. In winter it is a different story with the outside air temperature regularly well below -20 degrees for many months. However, our chefs inform me that for maintaining food quality a controlled freezing temperature is also very important. Our base maintains extensive frozen food reserves to last all winter and summer season in case resupply cannot occur.
All bases in Antarctica seem to have freezer units for storing food, even the bases where the local temperature is constantly well below -30 degrees. For example, one of the Japanese bases, Dome Fuji, reaches an air temperature high of -30 degrees in summer down to as low as -80 degrees in winter. That base is built well below the snow surface as snow is a great insulator allowing the buildings to maintain a constant temperature all year round.
Over the next few years Scott Base is undergoing extensive modifications and the regular kitchen freezer units have been placed outside where the radiator side of the freezer unit were visible. If you inspect the rear of your fridge or freezer at home you will feel that it is quite hot when the compressor is running. Heat energy is being pumped from the inside to the outside. As fuel is used to run the power generators down here when the wind speed is too low to generate power from the turbines, it made me wonder about the efficiency of running a freezer outdoors all year around.
Around Scott Base and nearby McMurdo station, older air conditioning plants and refrigerator units are often external to buildings however this is not the case at the South Pole station. This is because the common refrigerant gases used to cool a freezer work down to around -50 degrees. That is the typical lowest winter temperature here but it is much colder at the Pole, hence the units are indoors there.
Now days we think a lot more about our environment so when any freezer unit is being installed permanently we consider whether we can save power by recycling the heat generated by the freezing process and minimizing losses from defrost cycles by locating air intakes, radiators and fans away from wind-blown snow.