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Fun In The Sun -- Solar Pasteurization

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#1 Foster



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Posted 01 August 2012 - 11:04 PM

Fun In The Sun / Solar Pasteurization

Being all but banned from the kitchen and ceramic cook top stove, I needed another means to pasteurize cheaply. Free... That's even better!

The obvious choice, Solar.

I have built, tested, and will review the 4 different models I have worked with.(Not the type in general) I am not claiming these as my own ideas. I can say that I have researched, and will present, my own versions. Ratings will be 1-5, with 5 being best, 1 the worst. And yes, I'm saving the best for last. ;)

The basic ideas behind my builds were: Simplicity (How difficult to build), Safety, Functionality (Ease of use, Effectiveness) and Durability (how well it holds up). These are the criteria I shall rate. Each with a short comment.

A quality pair of sunglasses should always be worn while using a solar pasteurizer/cooker.

The first one I built was made from particle board. Plywood would have been a much better choice. The pics were lost when the ol' computer died. This solar wall oven designed by Barbara Kerr ( a Solar/alternative energy icon) is about as close as you can get in shape.


I could adjust the angle by flipping it on its back. Giving it 2 different angles, one for summer, one for winter. Single pane tempered glass with a blackened copper sheet as it's collector.

This design worked but was slow to heat. It wasn't adjusted to track the sun, it faced due south. The highest temp I recorded was about 175ºF.

The combination of weather, warping, and the wife's constant " Will you get that piece of crap out of my yard, your killing the grass" led to its demise. It was broken apart and will be used as kindling for heat this winter.

Simplicity: 1 Not an easy build
Safety: 3 Locking latch,tempered glass (still glass)
Functionality: 3 Slow, Rapid heat loss if opened
Durability: 2 Even painted particle board sucks. .

Overall: 2 Resisted wind, weathered badly

Edited by Foster, 02 August 2012 - 12:54 AM.

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#2 Foster



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Posted 02 August 2012 - 12:12 AM

For my next build I chose a box style. I thought " Wouldn't it be cool to build one from items that were commonly used in our fungal hobbies?" The plan was to use tubs, aluminum foil, and polyfil. Yeah sure, sounds simple enough lol.

I chose two PP5 rated storage tubs. An 18 gallon and a 10-12 gallon? Emails sent to the three major manufacturers of storage tubs (for this area) resulted in 1 reply (Stareatlights), 1 not answered (rub-a-maid) , and 1 invalid email address.

The one reply: "Our storage products are made of Polypropylene plastic,No PVC's, Latex, Teflon, polycarbonates, Phthalates chemicals, bisphenol A (BPA), or antibacterial chemicals are used in our manufacturing process.
Our products are 100% recyclable, and the triangular recycling symbol may be found on the bottom of all products,and bear the number "5" for recycling purposes if your community offers this service.
They can withstand temperatures of approximately 180 degrees Fahrenheit and 15 degrees Fahrenheit."
Pretty informative.

This was way more time consuming and difficult than it appeared. Here's the parts used. fsp3 with text parts layout.jpg

It took over a week of constant adjustment, modifications and trial and error to reach pasteurization temps in the blackened pasta pot.

It also took 2 panes of tempered glass, almost 2 rolls of alum foil, a shitload of foil wrapped cardboard for for insulation and spacing, constant attention and adjusting of angles, a 6 ft polyfil blanket, a blackened copper sheet, reinforced foil tape (which sucked and came loose), 2 bicycle inner tubes (seals), 3 types of window/door seals for the glass panes, sheet metal screws, and a cardboard/tape hinge for the inner pane.

The highest temp recorded in the pot was about 160º-170ºF. It took all day to get there.

The cardboard quickly became damp and funky due to condensation. The whole mess was torn apart after a couple weeks.

Here's some pics in use: boxinuseresizesmall.jpg

Simplicity: 1 - Way too much time and effort
Safety: 1 - 2 panes of tempered glass, 1 resting on top, not secured
Functionality: 1 - Needed constant adjustment, quickly lost heat if opened
Durability: 1 - Components failed, cardboard wicked moisture.

Overall: 1 - It works but is not feasible to use.

#3 Foster



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Posted 02 August 2012 - 12:51 AM

Next was the 3ft x 4ft Bubblefoil reflector type. Simple, Effective, and something I now consider a must have for emergencies. A couple cuts and a few folds, a paperclip or tape and you're in business. 3x4bubblefoilcutsshownresizesmall.jpg

Perfect for camping, backpacking, a day at the beach, park, or emergencies/ power outage.

It will substitute as a pillow, an extra insulator for a sleeping bag, a reflector for lost hikers to use a signal.

With this type setup, pasteurization temps could be achieved in a single blackened quart jar. Some adjustment for tracking the sun is required.


Here's my setup as pictured. A oven bag or spawn bag is used to hold in the heat. A block of wood or insulator is placed inside the bag. The blackened jar is placed on top of the insulator. The bag is then inflated and tied off. Kinda like pc'ing, you want the bag to make as little contact with hot surfaces as possible.

Ultimately you are at the mercy of the wind and gravity with this one. The larger it is the more energy it collects. Also the less stable it becomes.

Simplicity: 4 - As simple as it gets. Minimal components
Safety: 4 - -1 for the hot jar
Functionality 5 - Multiple uses, Will achieve pasteurization.
Durability 2 - Easy to clean, stability issues

Overall : 3 - Totally portable, but crumples in the lightest breeze

This is one everyone should have. Just in case. It can also be made from a mylar auto window shade.
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#4 Foster



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Posted 02 August 2012 - 01:13 AM

And finally! Presenting The FSP-1, or funG-L solar pasteurizer. This is my top pick for sure.

fung-L setupjarbagresizesmall.jpg

It is modeled after the funnel cooker designed by a BYU professor. I have made several modifications of my own.

This one I made from thin aluminum sheet. The shiny side was polished by hand to maximize reflection. It was cut and bent into the funnel shape.

The stand or base used is a #3 nursery pot. A bucket or cardboard box would work as well.

When properly secured, the FSP will withstand light wind. 10-15 mph steady, with gusts up to 20 mph was the max experienced while testing.

Rain and dust are easily cleaned off with a soft clean rag. Microfiber works well.

I only adjusted this one twice a day. Once from due east to south. Then later from south to due west.

Similar to the bubble foil, it uses the bag, jar, insulator setup.

I have pasteurized 2 qt jars per day without fail.

to be continued tomorrow. If you read this, please refrain from posting until I complete testing/formatting. Thanks :)
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#5 Foster



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Posted 02 August 2012 - 11:51 AM

Here's a pic of the highest temp reading I recorded.


It actually reached over 220ºf at times. How do I know? Because water boiled out of the jars.

The FSP-1 easily reached pasteurization temps and would also make a great cooker for food. Of all the models I have worked with, this one was the most efficient and fastest to heat up.

I will be experimenting with a larger vessel and modified design in the next few weeks. I think a half or gallon jar might heat up as well. Again, the larger the reflector is the more it collects, so I might try that too.

This is something I forgot to mention at the start of this thread. The last three models were tested using 3 different mediums in the jars/pot.
They were: poo/water, verm/water, and water alone. Water was the easiest/fastest to heat. The poo/water took a bit longer. The verm/water took the longest.

It would still easily reach over 160ºF in the FSP-1. No problem:thumbup:

Ok, so for heating, this one rocks. But what about the claims it can be used as a cooler also?

As the story goes, 2 funel types with double bagged jars were setup, aimed at the open night sky. Temps dropped to 47ºf that night, the jars had ICE. Hmmm, sounds a bit sketchy to me.

So I setup the FSP-1 with two digital min/max, indoor/outdoor thermometers. No vessel was used, just temps taken at ground level, the top of the FSP and inside the base. Hmmm, no substantial temp drops recorded.

The next night, I set it up again. This time with a single bagged, blackened jar of water which had pasteurized during the day. I had the two digi thermo's and a meat thermometer in the hole of the jar lid. At about 10-11pm the water temp was in the low 90's, upper 80"s. Outside temps were about the same when I reset the digi's min/max.

The next morning, shortly after 9am, I checked my temps. WHAT?! This cant be right! No way!

Max outside temp was 91.8ºF
Min outside temp was 73ºF

The temp of the water in the jar (drum roll please) 44ºF. That's right 44º!.

WOW! It did work. Hell we haven't had 40's since March or early April. Temps have been hovering around the 100ºF mark for close to 3 mo.

I double checked by trying the experiment again the next night. Had over 25ºf temp difference again. SsSsSWwWwWeEeEeETtTtT!

I'll add more about FSP as I remember things I forgot to mention, or do new tests.

Simplicity: ------ 4.5---- alum. cuts easily, bends easily, low maintenance.
Safety: ------ 4----- Thin alum. can be sharp if not sanded. Hot jar.
Functionality: -----5------ Achieves temps to cook food,minimal adjustment.
Durability: ------4.5----- Although thin, still rigid and solid. With proper care the FSP will last many years.

Overall: -------5--------- +1 for the cool factor, literally.

I've had a lot of fun with this project. Some real surprises too. Anyone interested in solar can easily find a ton of info with a quick search. And I'll answer as many questions as I can FME's.

Stay tuned! I'll soon let you know how you can have a custom, hand built and polished FSP-1 of your very own!

My FSP was built from 100% recycled material. Although I can say recycled, I can't say it was built for free. Sometimes even recycled materials can be costly.
Enjoy friends, Foster

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#6 kcmoxtractor


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Posted 02 August 2012 - 12:51 PM

nice thread!

ive read in a pdf file that you can dig a hole in your yard and fill it with grass clippings to accomplish the same thing
the grass clippings heat up to composting temps, which are same range as pasteurization temps. here's the quote-

If you have a big lawn, here's a cheap & easy way to pasteurize large quantities of substrate. Make a 3'x3', 2' deep bed of grass clippings
and water it. Set a large plastic garbage bag 1/3 to 1/2 full of moist substrate on the bed and adjust the bag to make an evenly
thick layer. Seal loosely. Next, mound grass clippings 2' deep over the bag and water. Cover with a blanket. Let set 3 days. The high
temperature from composting will pasteurize the substrate. Bill Russell, State College PA.

#7 riseabovethought


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Posted 02 August 2012 - 01:18 PM

Cool. Nice work Foster! Reminds me of a solar grill.

#8 Foster



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Posted 02 August 2012 - 01:24 PM

Thanks riseabovethought

Hey Kc, that sounds like an interesting plan. I think it just might work. With a bit of h.poo and green grass, it would compost and pasteurize itself.
Unfortunately all my grass is brown or dead from the drought. I'm assuming you need fresh green clippings to produce the kind of heat needed to pasteurize. I'd also make sure the trash bag is at least HDPE. Nasty melted plastic ain't fun.

I did try HDPE bags from a local grocery. The ones you put fruit in. It worked but eventually melted all over my jar and lid. The 2x4 wood insulator punctured small holes in the thin bags. Causing it to deflate and touch the jar.

You can also use the FSP in a hole in the ground. It reduces adjustment to none, and is probably much more stable. Not that stability has been a problem at all.

#9 Foster



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Posted 03 August 2012 - 12:20 PM

I have just a couple more things I want to mention. There are a couple styles of solar cookers/pasteurizers that are more effective than the ones I built. They will achieve much higher temps more quickly. (not something really needed for pasteurization). These are the Parabolic, and the Fresnel lens.

Both types concentrate the sun to a single point. Kinda like a magnifying glass can be used to start a fire.

I decided against these for several reasons. The main one is safety. The concentrated energy produced by both types is virtually invisible. Kids, pets, wildlife, and even adults could easily get a nasty burn by crossing paths with the concentrated sunlight.

I have also read horror stories where a true parabola was the cause of fires. Not while in use, but while being stored in the open against a building.

With the extreme drought conditions here, I wasn't willing to risk it.

The other reasons are simplicity and cost. A true parabola is pretty difficult to make and bend by hand. The Fresnel lens can be quite expensive.

There are probably DIY versions of the each that pose less risk of injury or fire. I just couldn't take the chance.

#10 LilBear



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Posted 03 August 2012 - 01:06 PM

Dig IT!

beautiful additions man!

The only thing better than free energy is free food haha

I've actually got a big roof on top of a warehouse I've been ooglin' with a lustful eye myself for use of bulk solar pasteurization.

it's either that, or build a steam room, which is money time and safety problem causing

probably just gonna build a big-ole' solar water heater and use that as a free energy source for the pasteurization/steam/(sauna?haha) room
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#11 Foster



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Posted 03 August 2012 - 01:57 PM

Thanks Lilbear. :)

probably just gonna build a big-ole' solar water heater and use that as a free energy source for the pasteurization/steam/(sauna?haha) room

Good idea. A solar water heater is, without a doubt, the most cost effective and provides the quickest return of any solar/alternative energy sources. An electric water heater can be blamed for as much as 1/3 of your total power bill monthly.

I have an outdoor wood burning stove/boiler. It heats water which is pumped in to a heat exchanger in a closed loop. The exchanger is mounted between my cold air return and the blower for my propane furnace. I love it.

It also has a second water line which is directly from my cold water line. While hot, it pre-heats all the water before it reaches the electric water heater. Eliminating the need for the electric water heater to kick on.

Right now, It's so hot and dry outside, I don't have it fired up. Occasionally, I have seen sparks being blown out the smoke stack. Not a good idea at this time.

I am thinking a solar water heater will be my next project. :)

#12 Myc


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Posted 03 August 2012 - 03:12 PM

Your design reminds me of Gaudi's architectural style - he chose to mimic nature for practical architectural design:
http://thisbigcity.n... /><br /><br />Examine the image in this photograph. In the ceiling, we see what appear to be very intense lights resembling HID fixtures. These are actually conical shaped holes formed into the roof dome. The nature of the cones seems to amplify or intensify light.
Just some design thoughts while you're experimenting.

#13 Foster



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Posted 03 August 2012 - 04:09 PM

Wow! Very cool Myc. The sheer size of that is incredible. Having those guys in the red orange jump suits really makes it's size stand out.

That is similar to another project I have researched, planned, and never got around to. Solar "tubes" for residential lighting. The "tubes" have the potential to bring natural lighting indoor.

There are a few companies already making these using highly polished stainless tube and a dome UV-filter/ cover.
A bit too pricey for me still.

Damn, I am so glad you brought this up, and posted that picture. I had all but forgotten about the Solar Lighting. I am making this my next project. Scaled down of course. I'm not sure enough about it to cut a hole in the roof. Yet!

I have discussed the possibility with a couple of indoor gardeners. It would sure be sweet to get the sunlight in to the garden.

Man... I'm all excited LOL, giggling and shit. Thanks Bro!

#14 Myc


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Posted 04 August 2012 - 09:23 AM

National Geographic had a really good article here awhile back. The insert for that month's magazine discussed the models and ratios used by Gaudi for design.
Notice the columns - they mimic trees. Pretty cool eh?
Here's another photo. A scale model of the lighting scheme.
Posted Image

What I thought you might do
Is to shape your parabolic reflector - based upon these natural proportions.
Another thing in which I'm extremely interested..........The cooling effect
In terms of physics, what you have is a way to concentrate light and trap the resulting heat.
My scientific mind wants to know how - by using two parabolas at night - how we achieve the opposite? "Cooling" is actually just "lack of heat". This is a really important thing you're onto.

Solar cooking
Parabolic refrigeration
No power usage
No food spoilage
And if the world collapses, we may all be camping real soon.
You may have in hand, an extremely valuable survival skill my friend. Astounding.

#15 Foster



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Posted 04 August 2012 - 12:23 PM

That scale model is really cool. I will do a bit more research and check out what I can find on Gaudi. If there is a way to make the FSP more efficient or effective, I will gladly give it a shot.

The cooling effect was the most surprising aspect of my testing. A former employer of mine in the hvac business told me over and over Heat goes to cold, always heat goes to cold. Meaning if something's hot, it is trying to cool. Now more than then I see exactly what he meant.

This is a quote from the physics professor/ designer on how it cools:
"During the day, the sun's rays are reflected onto the cooking vessel which becomes hot quickly. At night, heat from the vessel is radiated outward, towards empty space, which is very cold indeed (a "heat sink"). "

Thanks again for your input Myc, I always enjoy reading your thoughts and comments.

#16 anne halonium

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Posted 04 August 2012 - 01:05 PM

im into this.
trying to come to terms with it,
its pardigm shifting,

i can see where someone could find this useful.

#17 Myc


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Posted 04 August 2012 - 04:19 PM

I come back to re-iterate
We need to examine the "heat dissipation" properties of this tool.

In physical terms
All object have "heat" - no matter how "cold" we perceive them to be. Absolute zero is the complete cessation of molecular motion (theoretically). An object which has attained absolute zero is said to be "without heat".
The device you've presented warrants some very serious investigation.

It is my firm belief that we can mimic nature and accomplish much work through studying the elegance of natural design. Thousands of years of genetic evolution can't be wrong. Everything (except humans) follow a very organized plan.
I could go on ...... but enough said.
Paradigm shifting = using elegance to accomplish work rather than force.

#18 psycheholic


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Posted 05 August 2012 - 04:01 PM

Very creative Foster. I know this took quite a bit of time and money, thanks for sharing bro.

#19 Foster



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Posted 07 August 2012 - 01:47 AM

Thanks psycheholic. ;)
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#20 mycofish



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Posted 07 August 2012 - 05:36 PM

This is great...just what I need right now.

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