When you go camping for extended periods, dry ice is an excellent way of keeping your food cold or even frozen. You will be able to keep your food frozen for much longer and avoid it being submerged in a soggy mess at the bottom of the cooler.
What is dry ice?
Dry ice is solid carbon dioxide (CO2) and sublimates (turning from a solid to a gas state) at -109.2F or-78C. The fact that it bypasses the liquid phase, makes it a very good cooling agent. Dry ice has more than twice the cooling energy per weight than ice and almost three times by volume.
There are effectively 2 ways to use dry ice during your camping trip:
Use dry ice to make a freezer cooler.
This method is very useful if your camping trip is longer and you would like your food to be frozen for longer. You will dedicate one cooler with dry ice only and only store frozen food in it. Having a cooler like this will also allow you to have ice cream or other frozen treats on your trip!
Use dry ice to make a super cooler.
By layering dry ice and "wet ice" you will keep your ice frozen longer and also reduce the temperature of the cooler. However, dry ice does not like to get wet and sublimation will be much faster, so the dry ice won't last as long. The best way to do this is to place a layer of styrofoam in the bottom of the cooler (this will isolate the bottom of the cooler from the dry ice and stop it from getting brittle and cracking). Wrap the dry ice in newspaper and place it in the bottom of the cooler. Then add normal ice over the top and place the food on top. Avoid getting food too close to the dry ice, especially if it's fluids because it will freeze solid quickly.
How long will dry ice last in a cooler?
As a rule of thumb, dry is will evaporate at a rate of about 5-10 pounds per 24 hours. So it is best to purchase the ice right before you go on your camping trip.
Generally speaking 10 pounds of dry ice for every 15inches of your cooler size
Here is a rough guide for the amount of ice you need:
To extend the life of the ice, use a good quality cooler and keep it in the shade. Limited the amount of time you open the cooler, that's why the freezer cooler method works great.
Safety tips when camping with dry ice:
Using dry ice as a mosquito trap
Mosquitos are attracted to CO2 and 1 pound of dry ice will be like one human for a mosquito. This makes for a great trap and is also commonly used by scientists to catch mozzies for experiments.
Step 1 - Take a 2 litre soft drink bottle and cut the top off.
Step 2 - Fill it about 1/4 full with water and add a little bit of dishwashing soap to it. The soap will break the water tension and when a mosquito land on the water it will be trapped.
Step 3 - Put a small amount of dry ice in a cloth bag and suspend it over the top of the bottle.
The mosquitos will be attracted to the CO2 and land in the water.
Place the trap an appropriate amount away from your gathering.
Using dry ice on a camping trip works great. It can either keep your ice frozen for longer or enable an actual freezer for your trip, just make sure you follow common safety practices when using it.