Power Out, Lots Of Food In The Fridge

[dcarch]

Due to weather and human error, recently, millions of people were cut off from electric power for a long time. There are many advices you can find on-line as to what to do with your food in the refrigerator and freezer.

Basically, they advise you not to open the refrigerator door or the freezer door to keep the food cold longer.

I am not so sure.

Refrigerator:

Air has very low specific heat, only 0.018 BTU for one degree F per cubic foot. Let’s assume there are 5 cubic feet of air in your loaded 40 F refrigerator, and your room temperature is 85 F, each time you open the door and the entire 5 cu. Ft. of air is replaced by room air, you are only loosing 4.5 BTUs.

Not counting all the thermal mass of the metals, glass, food, plastic, beer, ---, if you have one gallon of water, for it to go from 40 F to 41 F, you will need 8.34 BTUs.

Freezer:

Not counting all the thermal mass of the metals, glass, food, plastic, -----. Assuming your freezer is 0 F. In a fully loaded freezer, let's assume you have one cu. Ft. of air in it.

If you open the freezer door and that one cu. Ft. of 0 F air is replaced by 85 F air, you will be loosing 0.81 BTU, and OTOH, if you have one gallon of ice cubes, for it to go from 0 F ice to 32 F water, you will need 1,709.7 BTUs, or, open the freezer door 2,110 times.

dcarch

[ScoopKW]

True, but not NEARLY as much fun as a barbecue grill, 25 friends, and red wine. (One thing I learned in Florida was to buy a case of red prior to a storm. At room temperature, it tastes better than beer or vin blanc.) Any time this happened back home, it was time to unload the freezer and do a heavy-duty block party.

Of course, we were never standing in knee-deep water at the time, either.

[Jaymes]

One thing folks in the know advise you to do in advance of an impending storm is to put a cupful of water into your freezer and freeze it. When frozen, place a small object (like a coin) on top of the ice. When the power comes back on and you check your cup, if the coin has dropped and there is ice over it, you know that things in the freezer have thawed at least to some degree and may not be safe to consume.

Too late for this advice this time perhaps. But next time....

[DanM]

I wonder if adding a block of dry ice to the fridge and freezer during an impending blackout (like the one from Irene) would help to keep the food cold longer.

[ScoopKW]

Freezing salt water in bread pans will work better than dry ice, which peters out too quick to be useful for more than a day.

[andiesenji]

If you wrap dry ice in several layers (a minimum of 1/2 inch thick all around) of newspaper - has to be a porous material - a piece that weighs 40 pounds will last for 36 to 48 hours in a closed cooler or in the fridge.

I personally did this for years when I traveled in my motorhome with a bunch of dogs and the fridge was not big enough to hold all the food.

I planned ahead and has the locations of every ice company that supplied dry ice on my route.

I had rubberized, insulated gloves for handling the stuff. This is important!

[ScoopKW]

Didn't know the newspaper trick. It's unlikely I'll ever need it again, but I'll keep it in mind. I always just threw blocks of it into the freezer and fridge. It's certainly convenient -- since it goes straight to gas.

Blocks of frozen salt water last about 48 hours in plastic bags. (One bag. Multiple bags last FAR longer. I've gotten a week out of them in the past.) Then use the melt to flush the toilet. It's certainly cheaper than dry ice, but not renewable during an extended power outage.

[Beth Wilson]

Around Northern Ontario you can have frequent power outages. It has gotten better in the last few years on the Island I live on since they have been fixing the infrastructure but still happens a few times a year. In September they usually have scheduled outages that last from 7am til 3 or 4pm. Makes for a good day to take a long hike or read on the beach.

We have been told by Health Officials that if the power has been out for more than four hours to toss things like mayo, eggs and milk.. I usually make that decision after 6 hours if it is really warm or not...for some reason these outages never seem to happen in the winter when you have the walk out freezer option like the back yard.

We have had power out for up to four days. I discovered it is important to make friends with those that have a generator. The freezer was closed for 2 days and was still fairly frozen. We ran the generator on it for an hour and half and voila it was frozen again. You plan when you open the freezer to grab what is close and make it a surprise for menu planning.

I gotta make friends with a person who gets a case of red for outages, I kinda like that plan and would totally contribute to a pot luck of fridge rescue meals. I think I should talk to the emergency preparedness committee about this idea :biggrin:

[DickL]

Good analysis-- it's often good to question the prevailing wisdom on things like this.

A complication that you might want to include is humidity. When water condenses, it gives off a lot of heat, and more (although not nearly as much) when it goes from liquid to solid form. (Of course, it will reabsorb heat when it goes from solid back to liquid, and any frost would be the first thing to melt, since it forms over other stuff.) It would be interesting to see the figures to see if humid air has substantially more effect than dry air. Maybe one would only have to open the freezer door 500 times (instead of two thousand plus) in a humid environment.

[judiu]

I belong to a fraternal organization here in South Florida; we generally have at least one generator for our social quarters and kitchen for extended power outages. Every one brought food from home during the aftermath of Hurricane Wilma, several years ago, volunteers cooked and we put out communal meals for our members, who were without power.