Discussion Board

Fridge that takes only 0.1 kWh a day

http://www.builditsolar.com/Projects/Conservation/chest_fridge.pdf

Only big cost is getting a used freezer... This article really inspired me as I have HATED our fridge at this house for over a year and previous house for 9 years!!!! Horribly noise and energy hogging and never quite big enough.

It's a great idea, but keep in mind that he used a Vestfrost freezer for this project, which is extremely energy-efficient and well-built to begin with. It's not clear how well this would work with other models.

When we purchased a new fridge a few years ago, we found a nice one with the freezer section below. I asked if we could turn the freezer way down and use it instead as vegetable storage? I was told that this would not work as first of all doing so would disable the rest of the fridge, as the two are linked...but also that the components running that freezer section were not designed to run at lower temps. In other words, you might have compressor problems, etc. So what seemed like an obvious, easy thing to do wasn't workable.

So you'd need to consider some engineering aspects to this project. I guess if I were considering it, I'd contact the author and ask if he's heard from anybody who's tried it with other models.

Thank you Anna, good insights I had not thought of!

If you do get one of these working, I hope you'll report on it here! What a great project, and a great way to use less electricity!

Have made inquiry to local fridge repair guy about any downside. Tried Maytag but they do not have any tech people available...

If I do it, probably quite awhile as we are pending a big move in location in next 6-12 months and lugging a giant freezer is not top of my priority list Now after... that's a whole new ball game

Just got off phone w/ repair guy who asked me more good, pointed questions. So I went and tracked down the original article. Seems things got a bit scrambled in the translation. The guy runs it 1 hour, 3X per day to maintain temp. All off solar, runs at 9 am, 12 noon, 3pm. Chest style freezer is mandatory so you don't loose much cold when open the door. Indeed if short cycle the compressor you risk burning it out. Also, you would almost certainly get wide difference in temp between hot/cold spots inside box.

Here is link to original article.
http://eveningrainfarm.com/category/off-grid-technology/

Interesting...it sounds like it might be tricky to get this to work. But, theoretically not impossible, especially if some company would manufacture a unit specifically designed to work like this.

I have been thinking that if you had the need to run a chest freezer anyway (I have one because of my large garden and infrequent shopping trips), you would have a way to get by without a fridge. My idea is you buy one of these well-insulated 5-day coolers (non-electric), like this:
http://www.4x4xplor.com/coleman-xtreme.html. You keep some bottles of water in the freezer, and put them into the cooler when you need to keep something cold. You rotate the water bottles as needed to keep it cold. Now, this would give you only limited space for fridge-stuff, but it might be enough if you changed how you do things. For example, a lot of the stuff in my fridge is storage (flax seeds, for example) that could be vaccuum packed and stored at room temp instead. During times of the year when there's more fresh produce, just add another cooler!

Recently we've been eating a lot of watermelon and sweet corn. When I bring these home they are too bulky to fit into my fridge, so I have set up a (regular style) cooler in the kitchen where I deposit the watermelon and bag of sweet corn. I pop in a couple of frozen water bottles and this keeps the produce nicely chilled for at least a day, often two days--once we've carved up the watermelon and eaten some of it, I chop up the rest and put it in a container in the fridge.

BTW, we have all these plastic drinking bottles but have switched to drinking out of stainless steel ones. I'm not throwing the plastic ones out, though--they make great freezer bottles. Fill just 80% full to leave room for expansion. You won't be drinking this water, just re-freezing it, so the plastic doesn't matter. They fit easily into crannies in the cooler and take a long time to melt, lasting much longer than ice cubes.

Anna, great ideas! Thermal mass is our friend...

I have friends who are off grid, solar w/ propane refridge. Their biggest energy expense, almost only one, is the propane. Apparently the guy in article runs his solely off the solar panels!

Yes, thermal mass is amazing! In fact, that's exactly what the original fridges were--a well-insulated "ice box" with a compartment for a large block of ice to keep the interior cold. Those blocks took a long, long time to melt. Delivery man would bring around replacement blocks.

People in the country used to cut blocks of ice in the winter from ponds and lakes, then haul them to a storage building where they'd be insulated with bales of straw. That ice would last all summer.

The coolest thing I heard is that if one of those storage buildings caught fire and burned to the ground, including the straw, it still would not melt the ice, due to the huge thermal mass involved. I think physics textbooks use this as an example problem (how much heat would it take to melt, etc.).

Knew a family in Colorado who made block ice during winter in their yard and dragged it into old walk in refridge in the converted restaurant they lived in. Packed in straw gave them free cold all summer.

That just makes me jealous! I'd love to do something like that...but you'd need the right kind of structure to put it in. Hmm...I'm thinking, I'm thinking...

Now for those who live in hot, dry climates (Arizona, for example), a zeer pot might be a way to keep vegetables cool:
http://www.slashfood.com/2006/09/28/how-cool-is-that-zeer-pot/ If you Google this you'll find a whole bunch of interesting articles and pictures.

I'd love to try this (I have some large unglazed planting pots I could experiment with) but I don't think it would work all that well in my climate. (I've read that it works if the humidity is under 20%.) If I put it somewhere indoors, it might not be ventilated enough, and i don't know how much cooling it would provide. Well, maybe this fall I'll have time to experiment to see.

Zeer pot should work well here in AZ in summer. If the grid goes down long term before I can get out of there, maybe I'll give it a go.

If it works (which, I agree, it should), it would be fairly easy to rig up some kind of passive slow-drip irrigation for wetting the sand, so you wouldn't need to tend it several times a day and the sand would stay wet. Garden stores have nifty systems with little drip-emitters for watering house plants. Something like this, hooked up to a jug of water elevated above the zeer pot, would keep it working nicely.

Sigh...I'd love to use this technology but I live in the wrong place. I think the ice blocks in the straw house are a better bet for us.

Big outer jug, smaller inner jug... should not take water that often I wouldn't think. Once a day at most maybe? but it depends on how much space between filled w/ sand and water and ambient temp and humidity, have to keep an eye on it at first to see... For sure would need to presoak pots and get them saturated first.

Lots of information can be found about converting chest freezers to refrigerators amongst the home brewing crowd. Do a search on homemade kegerators.

The drawback to doing this for food is condensation. The people who've done a chest freezer conversion and use it as a refrigerator all say that enough moisture pools at the bottom that it needs to be "mopped" or "toweled" up once a week.

Keep in mind also with their kilowatt usage that they are running small chest freezers - less than 10 cu ft.

If you want information on doing the conversion on an upright freezer, PM me.