Instructables

Build a simple solar still

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Picture of Build a simple solar still
I've posted here about the square foot solar cooker, and here is another of the many uses for it.
This is a solar alembic, or pot still, made from square foot mirrors, which can produce between 2 and 5 ounces of distillate on a lazy sunny afternoon.
 
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Step 1:

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It is not that great at making distilled water (without added reflectors as above), but can make essences, perfumes, and even ethanol.

Please note: it is illegal to distill ethanol except for fuel, and you must have a federal permit to do so.  However they are not that hard to get, and our government is actually encouraging the citizenry to experiment with this which is why I'm writing.  I am with a group who have one.

Here is the link for a permit, which you MUST have.  You need to specify that you will be making alcohol for fuel on the permit application.
http://www.ttb.gov/forms/f511074.pdf

Step 2:

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The Reflector

You need 3 square foot mirrors, about $7 at your hardware store to build the reflectors..

Step 3:

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Put them together with duct tape (carefully) to make a half box.

Step 4:

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You can run a bead of silicon along the seams.

Step 5:

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Be sure to have some backing on the mirrors (as above) as they are dangerous to carry about. You can use cardboard, or even better a good wood backing for safety.  Paint your wood with a good coat of shellac or paint to help preserve it in the weather.

Step 6:

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Your 'mash' bottle, outer cover insulating jar, and collector bottle can be had with a little scrounging in the recyclable bin, or from your local bar or casino.  For the outer insulator jar, I use both glass and PET plastic gallon jars.  I like the PET better because it insulates just a bit more, and is lightweight and unbreakable.
Cut a 1 inch hole in the middle of your jar lid to allow the beer bottle to poke through.
Gadget931 year ago
Perhaps as a spoiler one could put in 10% C2H5OH. That is some terrible stuff and I'm sure nobody would want to drink that.
cobergland (author)  Gadget931 year ago
Sorry, but don't know what that is...?
I'll give a hint. An alcohol with tho carbon atoms.
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Sorry, I was using nerd humor. That is the chemical structure of Ethanol. I was also using a bit of sarcasm as a joke.
Samw1 year ago
What if you created a wide angle back and a one way mirror front? Or would too much light energy be lost through the double pane of the one-way mirror?
cobergland (author)  Samw1 year ago
@ Samw, I'm not sure what a one-way mirror would do....
If you widen the angle of the mirrors, you may get a little more energy collected, but for my purposes the 90 degree configuration works perfectly.
I measured some soybeans once cooked under pressure in the cooker, and it reached around 240 degrees+. It was scary hot when I cracked the lid open, and hissing steam whooshed out everywhere.
So it has a good temperature range.
The way to increase the temps is to gain in reflecting area, which means add more mirrors, and keep it focused all the time, or super-insulate the inner cooking container.
However, the downside of this is that you will have to track the sun more often I suspect.
I really like the 90 degrees, because it takes minimal attention and tracking.
Since I'm a lazy old fart, I enjoy the 'set it and forget it' feature, and it can boil most things in under 2 and 1/2 hours if left alone, and can raise a quart of liquid about one degree per minute.
If you build one, do some tweaking and write back what you find out. Thanks.
tstrain1 year ago
From a naive distiller...how do you "condition" a copper pipe AND what is "mash?" Loved your Instructable! Thanks!
cobergland (author)  tstrain1 year ago
@tstrain, If you read through the comments section, it should answer your questions. Thanks for kind words....
Fuel, sure ;)
bpersun1 year ago
At step 6, you show a condenser that looks like it has a screw top lid.
Where did you get this? Is it glass or plastic?
Thanx, Lovely job!
cobergland (author)  bpersun1 year ago
Hi bpersun, the condenser is just a glass fruit juice bottle, and you can either put a #3 cork with a hole in it, or carefully drill out a 3/8 hole in the screw top lid. If you do the latter, the plastic seal inside the lid will help to seal the tubing. The tubing fits in the hole fairly snugly. Seems to work ok, but I don't know how many vapors can escape. I want to try sealing that hole area with a flour water mixture like the 'real' distillers do. Thanks for comment!
Muy buena idea tengo que probar me gusta mucho tu invento vivo en Sevilla España el sol nuca falta!
cobergland (author)  roberto sirigu1 year ago
Roberto, thank you I think? Me espanol is pobre.
loafers1 year ago
Very nice mate. Very convenient for those of us who enjoy a good camp in the bush. I've always wanted to try out making and using an alcohol stove. Is home brewing really illegal over in America?
cobergland (author)  loafers1 year ago
Hi loafers, it's not illegal to brew here, it's just illegal to distill. Alcohol stoves are great, and ethanol does not smell bad like burning rubbing alcohol. Ewwww.
arty1 year ago
Cool. Thanks. Well done. Your beer bottle in a PET bottle might make an automatic stock-tank heater, too.

Have you considered the flip-side? Instead of making a passive solar heater, how would you make a passive cooler? Every time you see a "Bridges May Be Icy" sign, you are seeing a warning of an artificial cold spot. Dew and frost on your windshield are another proof of something going below ambient temperature. If you could domesticate that cold, it would solve a lot of the world's problems. Looking at the local temperature/dew point charts, I see the spread is often just a few degrees. If you could build a artificial cold spot that took advantage of that small spread... Rural dwellers use about 37 gallons a day. Urban dwellers use more like 150 gallons per day. (The cities defend this figure by blaming the difference on the fire department and industrial use.)

But we don't need huge quantities to make an important difference. One Peace Corp volunteer-teacher wrote that she walked x (3?) miles each day before class, for 2 gallons of water, which had to suffice for all her cooking, washing and gardening.

I asked the State of Colorado what would be the legal consequences if I could "strike a rock with a staff and get water." They said that it would be classified as "weather modification:" and "under no circumstances would the water be yours." If this seems harsh, remember that the States and Municipalities have an enormous investment in "water rights" and delivery infrastructure. The "water rights" to one acre-foot of water cost between $3600 and $7200... of course you get that acre-foot of water every year, forever... if it is there to be got... and if your water-rights are senior.

In 1922 a S.B. Russell patented an "air well" that delivered 75-gallons a day in the winter and 150-gallons a day in the summer, but his airwell was concrete, thirty-foot on a side and five feet deep. The world needs an airwell that can sit on your kitchen counter and deliver half-a-gallon a day.

Capturing or retaining heat is easy. Avoiding or rejecting heat gain is tougher... and yet for centuries the Arabs have made ice by exposing a bowl of water to the night sky, then insulating it during the day. The Crusaders built "siege ponds" to provide water for their hilltop fortresses. History says this can be done, has been done, that man has known how to do it wholesale for thousands of years.

The guy who can figure out how to do it retail is going to spawn a billion dollar industry.

Feel challenged.
cobergland (author)  arty1 year ago
Arty, Carl at mb-soft.com has a system to capture water from pipes in the ground,condensing moist air you might enjoy reading that. He was trying to interest people in building this system for the folks in Haiti. Thank you for interesting comments.
mboese1 year ago
Sorry, another question, can stainless steel tubing be used instead of copper?
cobergland (author)  mboese1 year ago
From what I've read it can, and is probably superior. But too pricey for me...on a budget.
mboese1 year ago
I am interested in trying this, purely for scientific purposes, you know... ;) I am just curious about a few things. First, how do you "condition" the copper tubing, and second, what is in your mash? Thanks!
cobergland (author)  mboese1 year ago
Read 5 replies up for conditioning. You can use whatever mash you want, I've tried plain sugar wash, wines, and want to try wheat germ mash eventually, as well as the sunchokes if they will ferment..
chuckyd1 year ago
"Proof" is actually obtained by pouring alcohol over gunpowder and burning it.
The first five steps could be titled, "How to Make a Retroreflector."
cobergland (author)  JamesRPatrick1 year ago
Yes the 'Retroreflector' is the key to it all. 90 degrees works great, and it's not too big, not too small...just right. Thanks.
mlheran1 year ago
This is a great 'able, wow! Could it be used to distill water, and if so, what kind of conditioning is needed for the copper tubing?
cobergland (author)  mlheran1 year ago
@mlheran,, I haven't put much time into distilling water, but I think with the addition of a couple more mirrors (as above) it could do water. it would be interesting to find out how much water in a day it could do. However this setup will disinfect water, and if you look at my last instructable, it shows how. We need a minimal of a quart of 'safe' drinking water a day, and that's not if we do much physical work. AFA conditioning your copper, I've read that you should clean it well, and then run a mixture of white vinegar and water through it to make it potable. I have soaked the ends of my copper pipe in half and half (water and vinegar) and it cleans it amazingly well. There are some sites on distilling that can give you more info on that. Thanks for comment.
static1 year ago
I used 2 L. clear soda bottles as small hot water heaters. I found putting a length of black poly pipe or 2 inside the bottle helped heat it up faster. I think the biggest reason why they want to permit us to produce ethanol is to make sure we pay our road tax. Not that I mind road taxes, they are they only tax dollars I see working for me. :)
cobergland (author) 1 year ago
@ gn0stik, thanks for the info, it is always best to use the correct terminology, and for the link.
Until we all lobby our government to allow for the home use of nano-stills, I am going to concentrate on ethanol for fuel.
I am growing a batch of Jerusalem artichokes (sunchokes) to try, and in David Blume's most excellent book "Alcohol Can Be A Gas", he says that the chokes are a good feedstock. I highly recommend his book, as it is IMHO the bible of distilling, and it shows the possibility of a new world based on renewables. A great read, and I hope to finish it one day (it's looong and comprehensive), as it is a wonderful permaculture book.
My only objection is that he says solar distilling is basically not worth it, which as we suspect is wrong. I have attempted to reach him via his website, but have had no response. It is a wonderful book, and a 'should read'.
I am encouraged that folks are reading about this still, and grateful to Instructables for being a good place to post. I will continue to put up my goofy stuff from time to time, and hope that you will share your experiences if you build one of these. Thank you.
Thanks for the tips! Good Stuff!
gn0stik1 year ago
Isn't there an online version of the application?
Found it... https://www.ttbonline.gov/permitsonline/

You will need to create an account in order to submit the permit request.
gn0stik1 year ago
Ethanol distillates are called the "Wash" not the "Mash." Not that it matters much, but mash is the term used for beer, and is always comprised of grains. A wash can be pure cane sugar that has been fermented with champagne yeast, or even baker's yeast for that matter. Second, for any who would drink this, a word of caution: go read up on how to separate the "heads" from the "hearts" (drinkable) of your finished product. The first drops will smell like turpentine, and will burn in your nose, so start with a different container than the one you intend to keep the "hearts" in. Once it starts smelling like 151, or something similar that is drinkable. The methanol "head" can kill you, or blind you, not just rot your gut. It's hard on all your organs.. kidneys, liver, stomach, brain, etc. etc. But it makes a good cleaner. The last drops are called the "hinds" or "tails." and is less desireable due to impurities, and can be saved to add to the next batch of distillate to be redistilled. It's best to change containers when it begins to slow down, but has not yet stopped. This way, your "hearts" remain pure. All of that being said, if you are just making fuel... it is pretty much just set it and forget. And I have to say I do like the simplicity of this design.
bedwere1 year ago
Corn is used to feed cows because it is artificially cheap. In fact, federal agricultural subsidies (i.e. your tax money) are paid to corn producers.
Just a word of warning to those of you want to sample the very first thing that is going to distill off is going to be a small amount of methanol. I am not sure of the percentage produced in a typical batch but I believe it is around 3 to 4% of your total volume. It is not enough to kill you unless you got it pure but that is what makes "rockgut" whiskey. It is worth the time researching just in case you decide your body needs a little fuel. Great Instructable. Thanks for posting.
streetrod51 year ago
I wouldn't force-feed my cow to eat corn, so instead I will suffer in its place; I will *dramatic sigh* drink the corn ethanol (I mean "fuel my tractor!" yes, that is what I mean).

This is an elegant, simple design, and your 'Able is well-made. I will have to try this. (When my permit is approved, of course) Cheers!
cobergland (author)  streetrod51 year ago
Thank you streetrod5, for your comment.
As I understand it, it is not good for cows to eat corn, anyway, but then I'm not a farmer or rancher, so don't know. I would not be surprised if the leftover distillers mash is good as a supplemental feed, however. And it's probably good for chickens, etc., too. Maybe even humans.

Just a sidenote -- the 90 degree angle of these mirrors seems just about optimal. You shouldn't need to mess with it.
If you narrow the angle, you will get a hotter temperature quicker, but you will have to track the sun more often.
Conversely, if you widen the angle, you won't have to track as much, but your temps will likely be lower.
If you use this reflector to cook your foods (in blackened quart bottles) you should be able to cook most anything if you point the left edge of the reflector (as viewed from behind) right at the sun. As the sun moves (an illusion, we move...), it will get your stuff slowly and gently hotter and hotter, as it increasingly keeps adding heat. And, after the sun starts to wane, it will keep cooking after it reaches max. The insulating outer jar I think is what keeps it going.

Used as a still, the cooker is not a plug and play device -- you have to let it warm up. It takes a couple of hours in the sun before you notice anything. And then, you'll see a drop fall from the copper tubing into the collector jar. Then a bit later, another drop. When it gets up to good heat, I've recorded a drop about every 3 seconds. And it will keep at it until the alcohol level drops,and then it will gradually slow down. That's kind of how you can tell when it's all been captured.
Again, thanks for your kind words.