Refrigerator that doesn't use power - could we build this?

Hi
I read about a air refrigerant cooler that used a vertical shaft salvanious type wind mill to drive a compressor that was buried underground in the coolth of the earth . The compressor was made from a 60litre oil drum (12 imp gal) sorry dont know the US gal equiv, The piston was just a sheet of heavy plywood  and the crank from the windmill was arranged so it had a adjustable stroke. The idea was that the large volume of air that was compressed went into a buried receiver then up to the fridge cabinet where it released into a expansion phase that caused the cooling. The guy was operating it as a fridge at 4 psi and he was working on getting a little more power from the windmill and fixing some of the inefficiencies in the piston seal ect and he hoped to get it to 8 psi which he had shown with a mechanical driven compressor would give him a freezer . Its one of the things i am going to try when i get some time, My thoughts are to use the windmill to drive a horizontally opposed 2 diaphragms pump to overcome the leakages of the piston seal and build a more sophisticated copper condenser equiv to take all of the heat of compression out of the air before it is released in the fridge cabinet. I think it was on one of the Yahoo groups

My ante  Had an in ground ice house she used up to 80 years ago.  She filled it up with ice slabs cut from the Susquehanna River in January and it held till January the next year.  She went outside to the ice well and lifted a lid of the food chambers and grabbed fresh what ever.  There was a thriving ice cutting business that sold ice-house ice every January.  Price of ice was dictated by river ice thickness for the given year.

I regularly use a gas powered fridge that was probably built in 1953. As far as I know it has never been repaired beyond cleaning and maybe a new burner.   It has a little flame that burns all the time regulated by a thermostat.  Running this with a rocket stove would be a full time job.

The basic request was about refrigeration without power.  However, if it was rephrased as refrigeration without grid power then systems like a sundanzer might be useful.  Boat refrigeration uses eutectic mixtures to store coolth when power is available and then melt to keep things cold when power isn't available.  You can buy the bits to make these.  Propane powered fridges can use a lot of gas.  If you go that way enquire from people who use the particular model you are looking at.  They will also like the cooling fins kept clean so make sure you can access the back of the machine.   If you go with kerosene then try to ensure you have spare wicks and chimneys and an understanding of how to control temperature.  The thermostat system can be erratic.  They will probably need adjusting to suit the ambient temperature.  It is possible you can find an absorption refrigerator that just needs a new burner.

I also use an energy efficient electric fridge on an off grid system that provides mains quality power to run the rest of the house.  Works fine, is a normal kitchen refrigerator with a freezer section, single biggest user of electricity.

If you are just starting out then I would look at camping systems.  Some photovoltaic panels, with or without(see sundanzer) a battery, and a good quality portable electric refrigerator with a compressor (not an absorption one) that can make ice.  Maybe a solar regulator.  The most problematic piece is the refrigerator and I would take a lot of advice in looking at one, asking about reliability and efficiency.  This should get you a refrigerator that will keep perishables like milk and meat cold and either the ice or the battery would keep it cold overnight.  It is likely to be a little small compared to your average fridge.  It has inbuilt temperature control and does not need constant attention to burners or refurbishing ancient equipment.

Clyde

People have already mentioned our 2 solutions for energy free refrigeration. One we have actually done (root cellar) & one is still only half complete (insulated box cooled by well water).

Root cellar - was built as an experiment in the fall of 2019. We bought an 8'x14' insulated aluminum box off an old refrigerator truck from a junk yard. Total actual outlay of $ for this project was less than $500 (for aluminum box [$200 CAD], new foil backed foam insulation [~$200], & wood, spikes & propane/oxygen). We kept our costs down by half of our team being a consummate scrounger (aluminum I-beams retrieved from a cottage reno, aluminum shelving salvaged from renovation of the local hardware, old metal shed repurposed as an entrance, salvaged jackposts, etc) and by having our own big equipment (backhoe, dump truck, etc.).

We get to -40' in the winter here so we were curious about how a root cellar would function in our climate. After 3 winters with a Min/Max thermometer inside, we now know that temperatures range from 35-38'F from Sept cooling weather to June warming weather. Inside humidity runs about 90%+ all the time.

For safety we did the following:
- at the base of the front/back walls, added 6" aluminum I-beams the length of both walls & then prevented each wall from kicking in by constructing a sub-floor webbing/truss between these I-beams.
- to reinforce the 6" aluminum rafters, ran a 4"x4" wooden beam down the center of the ceiling & held it up with 2 jack-posts
- installed 1 passive intake vent in the floor of the shed vestibule under the middle of the front wall.
- installed 2 passive output vents high on the upper rear corners to exhaust warm air from either end.
- ran powerline underground from house for good, hands-free lighting but a good lantern could also do this job. Initially also thought [falsely] we might need the electric light as a supplementary heat source during really cold winter weather. But we've had temps as low as -45'F and no problems with freezing.

Advantages of a 7.5'x13.5' refrigerated room that uses no energy to cool:
- virtually unlimited refrigerator space for 2 people to easily store enough "fresh" root food for the year
- root vegetables store really well in peat moss or sand. We have happily eaten last years crop of potatoes in July of the following year
- also a great place to store pickles/cheese in brine
- store buckets of fresh eggs bathed a slaked lime. These "fresh" eggs have lasted for >15 months.
- lots of cool storage for food canned in Crown jars (no metal) with laser printed plastic rings to help keep the seals tight on the glass lids
- found that fruit (which likes less humid storage) does well in the cellar if kept in airtight coolers, separating each layer of fruit with paper. We've even macgyvered some 1-way airlocks to allow for off-gassing without exposing the fruit to the ambient high humidity  
- have just bought (so haven't yet tried) a set of gamma lids to store buckets of grains.
- used it to store dormant plants that can't yet be planted out (because our ground is still frozen or because we're busy with other projects)
- can help over-winter frost tender plants (ginger, calla lilies, celery root, sweet potatoes, etc. )
- if wanted, lots of room to easily add ice blocks (in sawdust) to extend refrigeration through summer months
- could use as a secure space to hang meat for proper aging
- and, as along as electronics were sealed from the humidity, this huge aluminum box could act as a Faraday Cage

Back in the day, I helped convert a 80,000 square foot apple storage to an REI sewing factory. Every wall was lined with four or more 2" pipes that carried ammonia to cool the four floors of the saw dust  (fine chips) walls of the warehouse.

Talk about a "run for the hills" thing if one ever broke, while charged.  Fortunately, when I got there, the pipes had been empty for at least ten years.  

SIDE NOTE: A lady who had horses was super happy to get the pipes for building a pen.

D Nikolls wrote:Ammonia is used in many cooling systems, primarily in RVs. It is a less efficient system than a compressor based unit, but has the advantage of being powerable by thermal energy, so you can run it off propane.

I hear they are really miserable when they eventually corrode through and leave RV very malodorous...

This is interesting; I DO know that before refrigeration, dairies were built over naturally cold springs and the milk, butter, etc would be stored in clay or wood containers in the cool water. Spring houses and Well houses also had  access to the cold spring where food would be stored; I know of one place that had a dairy, a Spring house, and several root cellars  all built around the head of a natural cool spring water head that was in use for several generations; the dairy  had to be modernized because they sold the milk; the rest of the produce that was stored in the well house and the root cellars was always well preserved...

The dairy and the farm were sold as the grand children were not interested in  keeping the farm; and it was all bought up by someone at some time....sad that it all is now gone

C. Letellier your post of the solar ice maker shows a genius idea (albeit one that requires ammonia), one I am afraid most folks did not "click on" to see the possibilities this offers.  So I am going to play a little cut and paste with YOUR link so that everyone see's what it is all about.  

Perhaps one of the clever minds here can come up with a smaller version for use on off grid homesteads??? No need to cut and store river/lake ice for summer cooling, just "grow your own ice" and use an old fashioned ice box or to chill a summer root cellar to a cool enough temperature.  If this unit costs $7,000 US to build, a unit 1/10th the size should be 1/10th the cost...or $700 - pricey, but a one off cost for continuous, maintenance free, labor free ice production as long as the sun shines!

"An ISAAC produces six blocks of ice each day, weighing ten kilograms each. If an icebox requires five kilograms of ice per day to stay cool, then one ISAAC will be able to supply domestic refrigeration to twelve households. The cost of a standard electric refrigerator, plus the constant requirement of expensive electricity, would be much higher.

The ISAAC Solar Icemaker operates in two modes. During the day, solar energy is used to generate liquid ammonia refrigerant. During the night, the generator is cooled by a thermosyphon and ice is formed in the evaporator compartment as ammonia is reabsorbed to the generator.

The ISAAC Solar Icemaker is an Intermittent Solar Ammonia-water Absorption Cycle. The ISAAC uses a parabolic trough solar collector and a compact and efficient design to produce ice with no fuel or electric input, and with no moving parts.

The daily ice production of the ISAAC is about 5 kg per square meter of collector, per sunny day. The construction of the ISAAC Solar Icemaker involves only welding, piping and sheet metal work, and there are no expensive materials. It is estimated that, when produced in-country where wages are low and transportation costs can be minimized, the 11 square meter ISAAC can be produced for less than $7,000. When produced in-country, the creation of urban employment is an additional advantage of ISAAC technology.    

The ISAAC design was developed by Energy Concepts Company. Over forty systems have been built and twenty installed in seven countries. The ISAAC is on display in Annapolis, Maryland and at Sandia National Lab, Albuquerque, New Mexico. ISAAC is now being distributed and commercialized by Solar Ice Co. "
https://www.energy-concepts.com/_pages/app_isaac_solar_ice_maker.htm

Kim Huse wrote:This is interesting; I DO know that before refrigeration, dairies were built over naturally cold springs and the milk, butter, etc would be stored in clay or wood containers in the cool water. Spring houses and Well houses also had  access to the cold spring where food would be stored; I know of one place that had a dairy, a Spring house, and several root cellars  all built around the head of a natural cool spring water head that was in use for several generations; the dairy  had to be modernized because they sold the milk; the rest of the produce that was stored in the well house and the root cellars was always well preserved...

The dairy and the farm were sold as the grand children were not interested in  keeping the farm; and it was all bought up by someone at some time....sad that it all is now gone

My grandfather's farm had an artesian well. Some previous owner built the milkhouse around it in such a way that water flowed into a concrete tank, where they would put metal milk buckets to keep cold. Then it fed into a system of pipes and water troughs to keep the cattle hydrated in all 3 barns. Any extra was channeled out into the irrigation canal, which meandered through several acres of fields, before emptying into the nearest river.

By the time I was old enough to remember anything, he had built a new milkhouse with an electric cooling tank. But, the artesian well is still flowing, and he still used that to water both crops and cattle. His farm was among the few that were unaffected by drought years.

After my grandfather passed away, my cousins and I did a walkthrough of the buildings. The concrete tank that the well first fed into had always seemed really shallow, but this time someone stuck their hand in the water, and we discovered that it was actually really deep. It was just so full of silt by that time that it looked shallow. My cousins and I stirred up the silt to try and see how deep we could go. About 2 feet down, there were jars of canned peaches, labelled with handwriting that none of us recognized. I wish we could have suctioned out the silt. I get the feeling it would have revealed a lot more, because we never did find the bottom of the tank!

Ellendra Nauriel wrote:After my grandfather passed away, my cousins and I did a walkthrough of the buildings. The concrete tank that the well first fed into had always seemed really shallow, but this time someone stuck their hand in the water, and we discovered that it was actually really deep. It was just so full of silt by that time that it looked shallow. My cousins and I stirred up the silt to try and see how deep we could go. About 2 feet down, there were jars of canned peaches, labelled with handwriting that none of us recognized. I wish we could have suctioned out the silt. I get the feeling it would have revealed a lot more, because we never did find the bottom of the tank!

Please tell me someone gave those peaches a try, at least a sniff. I volunteered to clean up the root cellar of a co-op house I lived at in Madison which had been out of use for some years. Found a case of mason jars full of grape juice, presumably from the vines growing along a fence in the yard. It tasted somewhere between regular grape juice and wine, seemed barely alcoholic if at all, but turned out to be one of my favorite things I've ever consumed...

Coydon Wallham wrote:

Ellendra Nauriel wrote:After my grandfather passed away, my cousins and I did a walkthrough of the buildings. The concrete tank that the well first fed into had always seemed really shallow, but this time someone stuck their hand in the water, and we discovered that it was actually really deep. It was just so full of silt by that time that it looked shallow. My cousins and I stirred up the silt to try and see how deep we could go. About 2 feet down, there were jars of canned peaches, labelled with handwriting that none of us recognized. I wish we could have suctioned out the silt. I get the feeling it would have revealed a lot more, because we never did find the bottom of the tank!

Please tell me someone gave those peaches a try, at least a sniff. I volunteered to clean up the root cellar of a co-op house I lived at in Madison which had been out of use for some years. Found a case of mason jars full of grape juice, presumably from the vines growing along a fence in the yard. It tasted somewhere between regular grape juice and wine, seemed barely alcoholic if at all, but turned out to be one of my favorite things I've ever consumed...

Unfortunately, no. At the time, we thought there was a chance they'd been put there recently by a guy who had been renting the barn. We weren't even sure whether or not he was still renting the place, so we were trying to tread lightly.

Thinking back, I am fairly certain they'd been there a long time, because of the design of the jars. But I didn't know that then.

Coolgarie food safes

I’ve always thought about building a solar chimney dug into ground, with screens and filters and possibly extra racks with material that self wetted to add evaporation into the ‘fridge’ to reduce temps / add humidity- or alternatively wrapping ‘ fridge’ container externally with self wetting ( material that has a corner in a large tank of water will wet itself) , my house is built on a hillside so the basement level would be buried/ wet wrapped,( in summer only ) then as it came into the ground level into my single story north side attached porch - where it would have the food for access in the house- and the container would continue thru the roof as a small solar chimney- to continually pull colder air thru ( with appropriate filters below food storage area.

The following system would require a bunch of pipes and a bunch of thermometers to manage, but it would not require any electrical power.  It's sort of a super-wofati-freezer idea meshed with a wofati idea, and a more regular passive solar house idea, and, and...

I have this idea to have a large berm behind my home with an insulated lower ceiling to the insulated upper floor to insulate the lower floor from external temps.  This future home would be semi-underground (mostly southern and western exposed), but totally above grade for drainage.  

In the berm, through a door in the North kitchen wall would be a walk-in Pantry, and, through double doors in the east back of the pantry, a walk-in root cellar.

Through a second set of double doors in the east side of the root cellar would be a walk-in freezer, which is a room full of iceblocks contained in some insulation of sorts (probably alternating milk crates - wood chips in one, and frozen milk jugs in others, and still others with frozen goods --- possibly all in old reclaimed chest freezers.  When a cold snap was coming a person could bring some milk crates full of water jugs outside, let them freeze, and then carry the crate into the cellar and ice room, and surround it with ones full of wood chips.  And as a person gets older, and carrying a whole crate of ice around might be too much, just carry one jug at a time.    

There would be pipes coming into both the root cellar and the ice room from outside and some other ones that would leave the ice room and root cellar into the house.  There would be some coming from the ice room to the root cellar as well.  The ones from the ice room to the cellar would go directly into a cedar box on the wall with a door on it that would have some thermal mass in it and would also contain the water line from the creek, bringing gravity-feed water under pressure to the house system and keeping the box cold every time one turns on the tap while also keeping the pipes from freezing (as this is just a cold cellar space).  This box is the fridge, which is a little out of the way, but not a huge chore.  All the pipes would have valves on them to close or open them.

Some of the pipes coming into the house from the root cellar or the ice room would go directly to an air intake inside the beginning of the burn chamber of the rocket mass heater to provide a fresh oxygen source.

Some of them would go against the outside of the burn barrel and the stove pipe using the heat from them to create an upward convection draw on the air inside the pipes, drawing air from the back rooms or outside to the ceiling of the room with the heater and increasing oxygen in the house.
 
So, part of the idea would also be that nearing the end of the growing season, I would be bringing cold air at night into the root cellar for better root and other veg storage over the winter, which can be a problem because often the root cellar is not cool enough when you start to store vegetables.

The air would be brought into the root cellar every night, when the rocket stove fired up as the season cools (even in the summer the air is often cold against the big mountains here at night).  Additonal pipes would bring air from outside, warmed by the cellar, but attached to the heating situation (burn barrel, and chimney, maybe), and vented at ceiling level.  Both the intake and the heat situation on the rocket stove would drive the system to draw outside air into and clean the air in the back rooms, while also serving to cool them and the fridge box.  An additional fridge box could be located in the freezer room or in the space between the double doors that go between the freezer room and the root cellar, and these would be fridge items that do not need to be accessed as regularly as those from the other fridge.    

There would also be a bypass that had a pipe that brought air specifically from outside into the in-house systems so that the air didn't have to come from the cellar berm.

So in this case, the only power that will be needed will be the power of the heating system, which is the heat created by the rapid burning of rocket fuel which is needed anyway.  The only work besides the pipes would be choosing which valves to open and close and doing it.

It would not require as much thinking as one might think either because the thermal mass in one back room or the other would be moderating and keeping whatever the temperature is in a pretty stable situation.  The house would be super-insulated from the berm, and each room back there would be insulated from each other and from the outside, and everything will be well drained in drain rock trenches.

The only problem that I could see with the system would be if the air in the cellar or the ice room was not nice smelling.  Then, I guess, that air would only be piped into the burning system as an oxygen source for the fire, and the valve would be shut off when not burning.  If some of the pipes end up being useless due to moving smelly air, then so be it, the cost waste would be minimal to try it out.  

Either way, I think the draw from the heat would create enough convection at any location to power the system, cooling whatever I want while heating what I want.

Here is a zeer style that looks interesting.
https://www.youtube.com/watch?v=WPYzV64dUuU

On a trip to Alaska we were taken to an oil pipeline. The oil had to be heated to flow through the pipes. Because of the permafrost layer in the ground, the pipeline had to have a way to freeze the pads that supported the pipeline. Ammonia was used. If I remember the temperature right, the pipe was around 400 degrees Fahrenheit and the ammonia would freeze to -175? No pumps, just the temperature of the pipe running the system.
Kat mentioned something about water cooling, I watched a video about running a pipe through your yard as a cheap geothermal system.
I could see running a pipe in to a cold lake the same way, but winter freezing might require two systems. One for summer, one for winter.
https://www.pbs.org/wgbh/americanexperience/features/pipeline-designs-protect-permafrost/

I saw a van build where a woman used a small 12 volt freezer (ran off solar or her van while she drives) to freeze multiple ice packs.  She built a super insulated cooler in the floor as her fridge kept cold with the ice packs.  She had 2 sets of the same ice packs (I think about 6 of them that fit perfectly into her mini freezer unit) and she switched them daily to keep her "fridge" running.  So although it required solar energy or gas from driving her van, these sources were already running, so she basically took advantage of that and got her refrigeration figured out in a pretty simple way using the least amount of energy.  Unsure if this would work in a very hot climate or not.  

Aaron Fletcher just uses an evaporated cooler he made out of wool to keep his dairy items at about 50 degrees. He said he just sprays it down with water 2-3 times a day.  

And if you live in a climate with a winter season you can simply have an old fridge outside.  I used to put the overflow of some groceries out on the porch in the winter when we used a small under the counter marine refrigerator inside.  Nothing that would attract animals of course.

A cold running stream can also be used for refrigeration, just need a very water tight vessel to submerge.  When we wild camp for longer than ice will last we use a water tight bag and sink it to the bottom of the lake so that's another an idea too!

There are a number of good concepts here, some proven, some worth trying.  In our climate, the ice house isn't viable with natural ice (southern KY -- winters don't get very cold, nor stay cold long enough to collect ice blocks).  We knew some people when we lived in Alaska who had built an ice house -- they didn't collect ice blocks, they just filled the floor of the ice house with water during cold weather and let it freeze, then covered it with a foot or two of sawdust.  The walls of the ice house were a foot thick, and filled with sawdust, as was the roof.  It worked extremely well.

What I have here, to be set up if we lose power long-term, is one solar panel (also meant to run a well pump), a camping or trucker style chest frig/freezer (looks like an ice chest but runs with a compressor), and a couple of ice chests.  We lived with a freezer and the ice chests for several months after we moved here -- I brought a freezer with me, but didn't have a refrigerator.  I found that ice chests need more insulation in them (the lids, in particular, don't seem to have any insulation in them at all), and if we were going to have to use that set-up permanently, I would prefer to build a better-insulated version.  We also didn't have AC, so it was pretty hot in the house in the summer, which didn't help.  Now that my brother and his wife also live here, we've been talking about building a combination root cellar/storm shelter that would serve both of our houses; the ice chests could be kept inside of that to make the ice last a little longer.

But one of the keys to living without refrigeration is reducing your need for refrigeration.  Shop out of the garden.  Don't make more food than your family can eat at each meal.  Don't put things in the frig that don't need to be kept cold (like eggs).  Turn milk into less perishable forms, like cheese, yogurt, kefir.  Summer meat can be from smaller animals -- butcher a rabbit or a chicken, and you can eat it up right away.  Butcher a pig or a beef, and you'll have to preserve the meat somehow unless you are feeding an army.  So there are two aspects to the refrigeration problem.  One is finding a way to keep things cool without the grid.  The other is changing your lifestyle a bit, to make better use of what refrigeration you do have, or eliminate the need for it as much as possible.

My aunt who I am having coffee with this morning mentioned she would can every bit of meat from a butchered animal. She has a root cellar next to a rock cliff here in West Virginia. Her log home was built by her and her husband and her dad from locally harvested wood. She said her dad wasn't much for straight lines, so some logs needed put up twice. They used motor oil to preserve the wood. The first 3 years you could see thru the logs to outside.
She has an exterior kitchen for canning.

There are refrigerators that use solar power to freeze ice during the daytime, then the "ice bank" is available to keep food cold overnight.

https://en.m.wikipedia.org/wiki/Icyball

Icyball is a good solution

Peter Roberts wrote:Hi
I read about a air refrigerant cooler that used a vertical shaft savonious type wind mill to drive a compressor …. The idea was that the large volume of air that was compressed went into a buried receiver then up to the fridge cabinet where it released into a expansion phase that caused the cooling. The guy was operating it as a fridge at 4 psi and he was working on getting a little more power from the windmill and fixing some of the inefficiencies in the piston seal ect and he hoped to get it to 8 psi which he had shown with a mechanical driven compressor would give him a freezer . Its one of the things i am going to try when i get some time, My thoughts are to use the windmill to drive a horizontally opposed 2 diaphragms pump to overcome the leakages of the piston seal and build a more sophisticated copper condenser equiv to take all of the heat of compression out of the air before it is released in the fridge cabinet. I think it was on one of the Yahoo groups

I considered some of the thermodynamics of this and did some calculations. I think it would help significantly to:

1) Use isothermal compression (liquid spray 2-phase flow or other heat exchanger in the compression space.

2) Rather than a nozzle, use an expansion piston & cylinder.

3) If the exhaust air exiting the fridge is significantly colder than ambient, use it to cool the air exiting the compressor (in a counter flow heat exchanger).  

Even at 4 psi this in theory could allow cooling as low as 33F, 0.5C.

Have you heard of the "SureChill Technology"? It's a patented fridge marketed mostly for vaccines but also for unreliable (or off grid) electricity. The way I understand it works is it has a closed-loop water system inside which gets cooled at the top. And since water is heaviest at 4C, it goes down. While the warmer water goes up and gets cooled again because of the ice. But it's also highly insulated so that it stays cool for multiple days without power. My goal is to eliminate an electric battery for the fridge altogether. The ice at the top would be the battery.

Their off-grid marketed one claims 73 hours power free operation at 32C (89F) outside temperature with temperature range inside between 5C and 12C (41-54F). The biggest vaccine marketed one is a combined fridge-freezer and claims 283 hours (11+ days) of power free operation at 43C (109F) outside while keeping the inside 2C to 8C. Uses 2x275W solar panels at 24V, directly connected and needs about 2kWh per day so about 2 and half hours of sun per day. 14L of freezer and 58L of fridge.

https://en.wikipedia.org/wiki/Sure_Chill_Technology

A video from the media:



And also their website: https://surechill.com/home-small-business/off-grid/

I wonder if this is possible as a DIY solution and if such solutions exist? First because I can't see prices on the website or where it's sold and second because a top door fridge would be way way more efficient.

That seems doable, and may already exist on the market. Supposing you wanted to DIY it or to try to save money, I suppose you could buy a chest freezer. Supposing it was the kind where they evaporator coil’s are wrapped around the inside, I’m thinking you could line the walls with some kind of water-based reusable ice packs, whether purchased or DIY.  I guess the only question left is how to prevent the food from freezing on a very sunny day, and I’m still pondering how to set up a controller for that.

So, with the setup I was describing, there’s a lot of heat flow around the freeze/thaw point with very little temperature change.  So a thermostat controller might not work well.

I thought of 3 ways to sense the change from water to ice.
1) Float sensor. A bag of water in a container of saltwater/antifreeze. Ice floats and flips an off-switch.

2) electric conductivity sensor. Slightly impure water will conduct electricity but ice won’t.

3) Measure the electrical capacitance at a frequency of say 30 kHz, where ice is about 20% that of water.

If that’s too complicated, an entirely different way is to have an ice maker drop ice into a icebox/“cooler”.

Along the lines of the “SureChill Tech”, (or in general a convective thermosiphon), I wonder if a thermally-driven bubble-pump could be made from a loop of tubing filled with carbonated water (aka “club soda” aka saturated CO2 solution). As with “SureChill tech” the loop would be cooler on top, warmer on the bottom. I’m thinking with an insulated down-tube and uninsulated up-tube. The warmer bottom would drive some CO2 out of solution, form bubbles with buoyancy that would rise to the top, circulating water along with it (aka a bubble pump).  At the cooler top, the CO2 would redissolve. The liquid would not freeze until below about –10 °C (-18°F).  If the bubbles stuck to the tubing walls too much, then the water-CO2 solution could be encapsulated in flexible polymer spheres.

chinese had this to make ice ,saltpeter powered,recycle and use again

Creighton Samuels wrote:

Bethany Dutch wrote:

I've been thinking lately about peak oil and energy and what ifs and it has got me thinking about replacing some important things in my life that use power with similar things that don't use power.

...Any thoughts?

I have a few.

While the zeer pot is a good, short term solution for regions with dry air, it doesn't work very well in places that it tends to get humid in summertime.

The best idea is to take a lesson from our homesteding forefathers before the age of powered refrigeration, and build a "root cellar".

Of course, the upcoming wofati freezer is basically a root cellar using additional designed principles to "save" the cold winter temps for mid-summer use.  One detail that I've thought a lot about in this kind of thing is a "heat pipe" network.  A heat pipe is just a pressure vessel made of threaded pipes, so that condensation of liquids in the highest portion can flow down into the lowest portion.  This uses some energy, but it's all latent energy, mostly just gravity. The bottom portion is placed inside your root cellar airspace, while the top portion is above everything and exposed to a northern sky (in the northern hemisphere, towards the nearest pole) while shaded from as much sunshine as possible.  Once the pipes are in place, the air needs to be vacuumed out and a measured amount of some kind of liquid needs to be put into that vacuum, to act as freon.  But it doesn't have to be freon; pure water works (down to about freezing, so not really good for a wofati freezer) and so does propane. And it doesn't take much propane, only a few cups probably; and it will never need more propane unless it leaks. What happens inside the pipes is, because it's not a mixed atmosphere, some of the propane will boil until the pressure "equalizes" between it's liquid and gas state. So long as there's some amount of liquid propane left across the temp range, we're fine.  But then we will quickly have a temp imbalance from top to bottom. When the top is hotter than the bottom, nothing happens except the pressure goes up some. But when the top is colder than the bottom, some magic happens.  Because pressure is related to temperature; when the top section gets cold, the pressure inside the pipe declines.  As it does so, the gas in the top will cool down until it reaches it's new dew temp (which is rising because of dropping pressures) and condenses inside the upper portion of the pipes. That condensed liquid then runs downhill until it drips into the lower section, which is hotter, and evaporates. Since gasses are lighter than liquids, the warmer gas is being pushed up the pipe as liquid flows down anytime the bottom is warmer than the top, until the liquid freezes.  In this way, so long as the vertical section of the pipe is insulated (and a shut-off value about mid-height for late spring and summer would help) any latent heat in the thermal mass will naturally convect out during winter nights without any human intervention nor energy using devices.  This method is limited to how cold your winter nights get, as well as the freezing temp of your chosen liquid, but it's very capable of moving a lot of heat under ideal conditions.

Updates? Have you made one??

D Nikolls wrote:Ammonia is used in many cooling systems, primarily in RVs. It is a less efficient system than a compressor based unit, but has the advantage of being powerable by thermal energy, so you can run it off propane.

I hear they are really miserable when they eventually corrode through and leave RV very malodorous...

'malodorous' - excellent choice of word.
My vocabulary has just been enriched.
Thank you.

C. Letellier wrote:You might want to look at systems like this.  I can't find a link for the older one that was easily buildable with no moving parts but here is a newer version.

solar ice maker.

Bit of a necropost, but would anyone be interested is a kickstarter to build a solar powered ice maker based on parabolic mirror and ammonia absorption (zero energy operation)?  I simply don't have time/space to build and validate but want to build one of these for our off-grid retirement place in the Philippines in a few years.  If anyone is intereted, I'd be will to do something like match any pledges dollar to dollar up to an amount that should allow this to be built.  I want someone publically committed but am willing to fund a good bit if the results are a validated build, instructions, some YouTube videos, etc that would be public domain when complete.

Anyone interested?

PS - I reached out to ISAAC and did not get a response.  Their web page is there but doesn't look to have been updated for around 2 years.  I also did a Way Back machine search for a great article on this topic (below).  Finally, there is a great construction blog on easy construction of a parabolic solar array (https://georgesworkshop.blogspot.com/2012/08/diy-solar-parabolic-trough-20-intro.html)