Off Grid Cabins, Winter, Freezing Temperatures, On Site Food Storage

[MountainDon]

This idea has been tossed around here before but mainly focused on what sort of foods to store with an eye to being unharmed by freezing.

The situation is: off grid therefore electric heat is out of the question. The cabin has an acre+ of trees to the south which truly ruins any solar heat as in using air or water collectors. Fifty to seventy percent shade on the south wall and roof. (PV electric modules are located 300 feet south on the edge of the meadow. Propane heat: it would really bother me to leave the cabin empty for weeks on end with the propane wall heater even left on low. Although I would like to do some experiments so I could see how much propane would be used to maintain the interior at something a little above freezing.

There are all sorts of dry foods, pasta, rice, flour, dried beans, potato flakes oninion flakes and powder, etc. that work. Last winter we also stocked some freeze dried foods, mostly meals as well as some f-d green peas, corn and green beans. The veggies worked well enough, being more like the frozen thing, but requiring a modified technique for preparation. The meals were okay, but not something I'd want a regular diet. Maybe I've spoiled ourselves with my regular cooking.    We also used dry mac 'n' cheese dinners more than once last winter.     Also on the try it once, eat it if there is nothing else to eat list were packaged "just add hot water" grocery store 'meals'.   

Part of the issue with us is that from about mid-December through March, maybe into April, we can not drive the last three miles of road to the cabin. Instead we snowshoe uphill from 8000 to 8800 feet. I do not like to back heavy loads anymore. Sp I/we want/need to have food ready for us in the cabin. Being off grid electric heat is out of the question. The unheated interior temperature dropped to a low of 20 degrees last winter. It was cold enough long enough to freeze 3/4 full jugs of water solid.

We would like to keep a small stock of things like canned tuna, salmon, sardines, chicken, spaghetti sauce, tomatoes, green chilies and green chili sauce, fruit, baked beans, some soups, etc. That's out of the question without heat as glass jars break and cans bulge and may develop seam problems leading to spoilage.

I was mulling ideas over in my head all weekend while we were up there. Here are some of my ideas.

1. Using the excess solar electric to provide heat to keep a small food locker warm. Discarded after a consult with a respected person in the PV installation industry. Also discarded after my calculations revealed that even with all our winter time power generation going into heat our system is too small to be really a good bet. Although, I will admit I have a hankering to do something experimental to see if my calcs are right. 

2. Variation on the above, using the battery enclosure with insulation added. After all there are 800 pounds of batteries to act as a heat sink/moderator. Discarded for the same reasons. Option 1A is try the excess electric. Option 2B is a little crazy.... see below*

3. Maintain the interior at 36 to 40 degrees using the propane wall heater. I hate thought of all those BTU's being bought and spent and me not being there.  Add to that, our current propane supply is limited to 40 pound cylinders, two hooked up at one time through the auto change over regulator. Thus far, they are more than ample for our needs. Having a 200-250 gallon tank would provide enough for low level maintenance heat. However, the propane suppliers all want two sales/refills a year before they will do a cheap rental on the tank. Last year we used something like 100 - 1200 gallons all year.

Now we have some crazy ideas that sprouted from my brain. Pilot lights do not use all that much propane. We run our water heater on the pilot setting only, nearly all the time. With extra insulation it provides us with all the hot water, really hot water, we can normally use.

*2B.  same insulated battery compartment. Yes there is unused empty space in it. Build a pilot light burner enclosure that draws fresh air from outside, burns in a sealed combustion chamber, and exhausts through top or end of box. Use a muffler for a combustion chamber? Disadvantage: fuel use. Lots of construction details. Advantages: keeps batteries warm too. Probably have the only one on the block.

4. Build a box cabinet on rollers. It would have one side open. On rollers it could be rolled against the wall over the propane wall heater. With the wall heater left on pilot only it would keep the interior of the box/cabinet warm.    Disadvantage: fuel use, need to store it somewhere most of the year when not needed. need to build it.

5. Similar idea, but build a wall cabinet and place it above the wall heater. The shelves and cabinet bottom would be expanded steel to allow air to rise through it. Make a removable "skirt" to fit the space between the heater top and the cabinet bottom. That would duct the heat upwards through the cabinet.  Disadvantage: wife not sure of the appearance. Fuel use. Need to build it.

6. Remove insulation from the water heater under the kitchen counter. Leave heater pilot on and the heat from the burner/tank would warm the cabinet space. Disadvantage: fuel use, the work/time required to perform a seasonal change of removing and replacing the insulation.

7. Use the range oven. Light the pilot and leave it burn. Put items that are not to be frozen in the oven. Advantage: no seasonal change over, nothing to build. Disadvantage: fuel use. Not very large, but likely good for our use. Would have to empty oven in order to bake/cook in oven.


After you finish laughing, rolling your eyes, etc. please feel free to contribute or critique.

[waggin]

What's your frost depth there?  In other words, could you dig a hole and put a well-insulated trap door/access port over it?  Depending on the desired volume for storage and access type, you could approach that a few different ways.  Would you want it big enough for human access or simply a container that could be raised via some pulley system like an underground dumb waiter inside a 12" or so diameter pipe?  These are some random thoughts, but maybe someone else has actually put something into practice.

[suburbancowboy]

When I was a kid growing up in the country in Idaho all the old timers had root cellar attached to there houses that where unheated and they had everything from potatoes, carrots and squash and all sorts of canned goods in mason jars.  Put it down in the ground far enough with an insulated top you should be good all winter long.  My grand parents used theirs up to 10 years ago when my grandfather died at 91.

[rick91351]

A cellar would to me be the most logical.  You certainly are not hurting for room or space to build one.  How about an insulated box under under the gazebo?  How far down in the cistern did it freeze last year?  Would that be a fair gauge as to how deep?     

[Phssthpok]

Hrmm...

My first thought would be to set up your CC for a dump load, and use it to run heating elements in an insulated enclosure, but it sounds like that's an option which has already been deemed nonviable.


Perhaps build a false bottom on your kitchen cupboards (or in your pantry) that would allow you to install lines through which your pilot-light-only water heater could thermosiphon?

A manual valve tapped into the outlet side of the water heater would allow you to bypass the 'heat-bars' when you're not away, and some very thin rigid insulation placed inside the cupboards should be enough to keep things above freezing when the water cycles through.

True it would involve some construction, but it would be a one time thing and use no more energy than you already use keeping your tank from freezing (assuming you don't drain it every time you leave).

[Pritch]

Don, you could build a "hobby" sized solar collector to heat water, which could be used ot keep an insulated cabinet warm.  Depending how it worked out, perhaps you'll get the bug to go full scale.  Check out Gary's designs over at Build It Solar. 

[Redoverfarm]

Don off the top of my head at 5:30A would be to build an insulated mini root cellar and use a couple solar skylight tubes to heat it during the day.  The insulated portion should make it last til the next days sun.  Of course the tube face would have to be elivated above the annual snow fall level.   Maybe after I am awake more a variation will develope.

[Minicup28]

We too have to snowshoe in the last half mile in the winter time with a 400' - 500' elevation change depending on how far I can get with the truck. We leave a few pounds of spaghetti stocked there and only have to carry a can of sauce & bread for few days at a time.
I just haven't found an "instant" beer powder to carry in that is palatable.

[phalynx]

I know this doesn't directly answer your question but what about buying a used snowmobile?  You could then pack all you want and not have to heat anything.

[Squirl]

We too have to snowshoe in the last half mile in the winter time with a 400' - 500' elevation change depending on how far I can get with the truck. We leave a few pounds of spaghetti stocked there and only have to carry a can of sauce & bread for few days at a time.
I just haven't found an "instant" beer powder to carry in that is palatable.

I keep whisky.  

A few of my ideas have been shared here.  I read a post a few days ago about a person who built a cheese cellar just by digging a hole.  He lined the whole with a large 40 gallon plastic trash can.  He put a few inches of insulation overtop.  He then packaged his cheese in an additional bucket inside.  Supposedly, it never froze.  

My concern with the pilot light solution is oxygen.  If there is an insulated enclosure around a flame, I could imagine the oxygen getting used up very quickly, then the container just filling with propane.  

I would love to see your calculations on the dump load option.  100 watts a day should be enough to keep a fridge above freezing.  It already would have insulation from the extreme colds by being in the house.  The temperature rise should be too great to keep it above 32.

[Shawn B]

I think that the oven idea would work for a limited supply of canned goods, jars, etc.

For the long term I would either:

1. Dig a root cellar type pit


2. Build a pantry type area in the main cabin and install a small 8,000 BTU propane heater, set the thermostat at 40F or so.


3. Construct a box out of plywood, insulate it with foil faced foam board on the inside, expanded metal for shelves, use a 40W, 60W, 75W (have to experiment) light bulb based on the size of box. Wire in a thermostat and set at 35F - 40F etc. You can also insulate the outside for extra R value.

We used one of these at the mill, they called it a North Dakota microwave. Except they used a 100 W bulb in a large microwave shaped box and left the light on 24/7......you could get soup too hot to eat.

[UK4X4]

A cellar would be my first choice..............but there are many ways to skin a cat !

How big is your solar array and batteries and what sort of power do you make a day in winter ?

do you have a sunny enough spot on the roof  for a solar heat collector ?

here in the middle east we have passive cooled shelters, rather than a freezing problem.............

but they work on having a large tank of fluid beneath the cabin, deep enough to not get heat from the midday sun.

A small solar panel circulates this cool fluid up and around the cabinet on a thermostat- its a balanced system size of container V's the wattage of the equipment to be cooled.

So taking this as an idea,and not really wanting to store food under the cabin........lets take it the other way arround.

A super insulated food cabinet

Upper fluid solar heater - undercabin insulated heat storage.................could be the same big dustbin in a hole lined with insulation

to be continued......dinner awaits

[NM_Shooter]

Don, I would suggest a solar hotbox. 

You don't need to keep a truckload of food warm.  And you don't have to keep it very warm at that.  Don't use your electricity to make heat, use it to move air. 

Build yourself a decent sized chest.  Don't use your battery enclosure, as you will have to insulate well, and do you really want outgassing batteries dumping corrosive gas on your metal cans? 

Build a small, super insulated box.  Two layers of 2" foam insulation all the way around.  Build a small solar air collector to sit on top, with enough pitch to keep the snow off.  Your cabinet would also have to be maybe 4' off the ground too. 

Buy a small muffin 12V DC fan, to push air from the collector into the box.  You could do it convectively (sp?), but you don't want to overheat either, and I would not know how to shut it off without some active vent controls.  You might need to plumb two traps in your air ducting so that the vents enter the box from below to avoid heat loss.

Use two cheapo thermostats.  One in the solar collector to only turn on if the temperature is above a setpoint (what's the minimum temp on a cheapie thermostat?).  Use another one in the food box to turn off if the box exceeds 80 degrees. 

You only need to keep the average temperature in the box above 35 or so.  The food will provide a nice thermal mass.  Your risk is if you have many days of cloud cover, but I would think that you should be able to survive two days if you insulate well, and we are mostly sunny here!  And I bet that on a sunny day it will be no problem at all to get the innards up to 80 degrees.  This sounds like a fun project.

[UK4X4]

well the last post is similar, but i was thinking liquid filled, as with air you will need to be close
fluid hold heats longer and will travel further.

daytime like the above post using the day time highs to heat all the goods in the cabinet, fluid circulates from roof to cabinet uisng a small PV cell and direct to a pump

Night you use the cellar resorvoir if required,using the existing PV system

If you wanted to get technical............during the day depending on the panel temp- storage temp and the lower resorvoir, the roof heater could also circulate down into the lower resorvoir to store any extra heat developed in the day.

That would mean some smart wiring - relays and thermostats........probably more than you want to do but would make a nice project !

[Squirl]

I just thought of another idea.  I know that solar is out of the question for you.  You could also build a compost heated box.  With some good insulation it will always stay above freezing.  You might even be able to use a scrap chest freezer.  The only problems are with proper sanitation.  You would have to carefully separate the compartments or build them as two separate containers and pipe antifreeze between them.  I just don't know how much electricity this would require.

[Proud_Poppa]

I agree with those who've suggested a root cellar. Very old technology with nothing to break down is usually better than a hi tech one. It also provides something of an emergency shelter.

[phalynx]

I know its fun to come up with all of these solutions.  Don, your problem isn't food storage, its food transportation.  Unless you are just itching to solve the food storage issue, I think you should look at transportation.  The transportation won't go out while you are away from the cabin.  It won't spoil while you are gone.  It doesn't involve a fire risk to your cabin while you are gone.  It won't have an electrical fire while you are gone. etc......

Just saying.

[firefox]

If you own the land along the path that you take when the snow makes it impassable, then consider the following. Make a miniature ski lift just for your packs. Have the motor for it powered from your car generators.  Put marker tags on the cable so you know when it reaches the top. Allow for tree growth.
This needs to be carefully thought out, but should work.
I also second the root celler idea. Suposedly if you get down far enough, the temperature should stabalize at about 55 degrees.
That and plenty of insulation.
Hope this at least gives you a few laughs.
Bruce

[MountainDon]

Thanks for all the replies, thoughts. I'm mulling things over.

A couple notes:

Snowmobile is out. Tried that, it didn't work well. Too much distance that winds around slopes. We'd need a snow machine made more for virgin snow transport use and in NM those are not common for used and it's too many $$ to buy new.

I've thought of using the hot water from the water heater on pilot. BTW, we don't leave it on all winter. Yet.

A cellar could be done next year. My friend/neighbor with the equipment has taken the backhoe down from the mountains already this year. I'm not digging by hand.

Using solar is doubtful. It's the trees, 55 to 70 ft ponderosa pines. With the cabin at the top of a ridge that falls away to the south, in the winter the sun's low angle has it struggling through the tree tops all day. There is always some sun, but quite often more shadows than bright spots. I intend on monitoring that a little more closely this winter when we are up there.    Maybe it would work with a larger than necessary collector?

If I was doing solar heat collection I believe I'd do a water/anti-freeze system. The water would be useful as a heat sink as somebody pointed out.  Pritch and UK4x4   There is power available for a small circulation pump. Where to place the collector for best results is the question.

Compost heat is not going to work. The composting toilet freezes as it is.

Bruce, we can always count on you for innovation. All but 1/4 mile of the distance is forest service though. They might not be amenable to that.

Thinking/listening hat is still on.   

[phalynx]

Hmmm, if you could get your hands on a small amount of plutonium.  

Could you do a glycol filled black water tank with a passive flow to a small radiator in a box?  Another thought would be a solar panel hooked directly to a peltier cooler/heater.  

[NM_Shooter]

Hmmm, if you could get your hands on a small amount of plutonium.  

Could you do a glycol filled black water tank with a passive flow to a small radiator in a box?  Another thought would be a solar panel hooked directly to a peltier cooler/heater.  

Peltier is out, as it is too lossy.  An electrical heating element is about as close to perfect as you can get for converting electricity to heat. 

If you can't use the sun directly, I think you either :

1)  Need to burn something.  Costly
2)  Need to dig a hole.  NRE, but labor intensive
3)  Build an insulated box and use your excess electricity from the big solar panels.  (Hey... can you run a small AC powered freezer in "reverse" and switch the source and supply lines on the compressor to keep the food warm instead of cold?)

[Pritch]

Don,

If you do make a solar collector, you could run a loop under the composting toilet as well. 

[rick91351]

Could you use one of those large heater / coolers that the truck stops carry?  I don't know how much they draw but you might check that out.  Actually the old style cellar looks the best to me.  Especially anyone that might be looking at living in their cabin year around or might have to move there because of tough times should have a cellar.  Okay I am a realist or is that a survivalist.  Build it and you can always use it for a bomb shelter.    Hey if nothing else grow mushrooms.     

[firefox]

Thanks Don! Here is another of my crazy ideas. If you mounted
a solar panel on a pole and managed to mount the pole to the top
portion of a tall tree, you could get more dependable power.
Of course, you would need to find a good tree climber to do this.
Bruce

[MountainDon]

The more I think about this the more I think that a hole in the ground, a root cellar or a solar powered liquid collector system may be the best long term solution, although I still have an inclination to investigate just what the excess electric could do with a well insulated and heavily heat sinked box/cabinet.   


For those who still think solar is the way to go, here's a sketch that may help explain my doubts about the efficiency let alone the efficacy....



South is to the left. Winter sun is low as drawn. Even with higher sun angles we have lots of shade on the cabin and most nearby areas. Further south, about a 1/4 mile from the PV panels the ground rises to a height about the same height as where the cabin is.