This past weekend was a busy one at the Sebastopol Demonstration Energy Garden. After a summer of soaking in sun and filling their stalks and seeds with sugars and starches, our Dale Sorghum crops went full cycle. From the 212 sq ft. that we had under cultivation we harvested 9 kg of dry seed and 115kg of sugar rich stalks. From the stalks that we harvested in addition to the 110 kg of stalk that were donated to us by Live Power farms (225 kg in total), we produced 10 gallons of sorghum juice. Of the 10 gallons produced, we fermented 8 gallons and with the other two produced approximately 57 oz of sweet sorghum syrup; this demonstrates the multiple possibilities that the crop offers. In addition we were able to utilize the carbon in the pressed stalks by adding what we didn’t use as a layer in our sheet mulch as an ingredient to our compost piles. The chickens quickly consumed the fresh leaves that topped each pile.

It took three of us approximately three hours on Friday to harvest the stalks and seeds; this includes removing the leaves from the stalks. The process entailed one man cutting the stalks at their base with a pair of hand held clippers while another tied the stalks in bundles and removed the seeded florets which were processed by a third. The seeds were separated and laid thin upon screens in the sun to be dehydrated and the stalks were stacked in the shade to be pressed the next day.

To press the stalks it required three people an additional 3.5 hours of labor on Saturday. We used the Improved Chattanooga #12 to press the stalks and caught the juice in 5 gallon buckets; the juice that emerged was a pea green and contained 15% sugar by volume. By comparing the measured weights (lbs) of bundles of four stalks with the volume (mL) of liquid that emerged we determined that on average 162.3 ml of juice is produced for every 1 kg of stalk pressed.

Overall harvesting and processing the stalks required about 21 hours of labor. We produced 10 gallons at 15% sugar from the 225 kg of stalk that we pressed giving us a 22.5:1 ratio of kilograms of stalk for each gallon of juice produced.

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Data published in the Alternative Field Crops Manual reports yields of 10 ton/acre for Dale Sorghum, of which 70% is comprised of the stalk. This is synonymous to 6350.3 kg of stalk/acre, which would indicate that 282.24 gallons could be achieved for each acre of Dale Sorghum under cultivation. Seeing that the juice produced from pressing the stalks is 15% sugar, fermentation should yield 282.24 gallons of mash at 7.5% alcohol. This shows that from one acre of Dale Sorghum, 21.17 gallons of 200 proof ethanol can be produced; the theoretical yield that they indicate however is over 400 gallons/acre.

Data published by Morris J. Bitzer at Blairsville, GA, and Quicksand, KY shows yields of Dale Sorghum at 20 tons of stalk/acre, 20321.28 kg stalk/acre, double the yield proposed by the Alternative Field Crops Manual, whose data was compiled from Waseca, MN.

Data published by Oak Ridge National Labratory, acquired from 4 different test sites in Indiana and Alabama, reported yields of 22.2 Mg/ha (9.9 tons/acre), similar to that published by Alternative Field Crops Manual.

Data Published by Texas A&M Extension agronomist, Juerg Blumenthal said the highest yield he'd acheived was 12.4 tons of dry matter per acre with the production of 395 gallons of ethanol per acre.

No indication of the proof of alcohol produced was provided in any of these studies, but I do not see how it is possible to yield such high volumes per acre. In each case either the juice pressed from the stalks is of a higher sugar percentage, their method of pressing is more efficient, or the sorghum is being grown in higher densities; none of this information was provided. Somehow, in each case, higher volumes of ethanol per acre were produced from lower masses of stalks per acre

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Proposed yields of sorghum stalk/acre: 10 ton/acre, 12.4 ton/acre, 22.2 Mg/ha (9.9 tons/acre), 20 ton/acre

Average = 13.075 ton per acre

1 acre = 43559.46 sqft

Harvested 212 sq ft = 0.005 acre

0.005 * 13.075 = 0.065 ton/acre

1 ton = 907 kg

Harvested 115 kg stalk = 0.127 ton stalk/0.005 acre = 25.4 ton stalk/acre

*25.4 tons stalk/acre being grown on site > 13.075 ton/acre proposed yield

Proposed yields of ethanol/acre: 400 gallons of ethanol/acre, 395 gallons

Average = 397.5 gallons ethanol/acre

Produced 10 gallon juice from 225kg stalk, of which 115 were grown on site

115/225 = 0.51 * 10= 5.1 gallons juice produced from grown sorghum

1 acre/0.005 acre = 200 * 5.1 gallons of juice produced = 1020 gallons of juice/acre

15% sugar will ferment to 7.5% ethanol

1020 gallon juice/acre * 7.5% ethanol after fermentation = 76.5 gallons ethanol/acre

*76.5 gallon of ethanol/acre produced < 397.5 gallon ethanol/acre proposed. This data correlates more with the projected 21.17 gallons of ethanol/acre that I proposed based on the obtained 22.5 kg stalk:gallon juice ratio and the assumption that starting with a 15% sugar content will produce a 7.5% alcoholic mash after fermentation.

Heres a video of Sorghum Syrup being made at Kentucky State University.

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While we are collecting fallen apples for the production of ethanol, we are also collecting those that are ripe for human consumption. So as to avoid contamination we rented a commercial device very similar to ours which runs off an electric motor.

Despite this device using an electric motor, the process of mascerating the apples and then pressing them took about as long as if we'd used our own manual contraption. The motor often jammed; each time this occured we had to remove the apples and refill the funnel.

The device did have many desireable traits however. The barrel which collected the mascerated apples was on the same platform as the pressing barrel; this made sliding one over to be swaped out very easy. Also the device was on wheels making it portable.

We filtered out the pulp of the cider using cheese cloth, and sealed each bottle by baking them at 200 degrees farenheit in the oven. In total, over the course of 4 hours we produces approximately 12 gallons of cider.

We harvested the buckwheat that we planted earlier this season in a 40 square foot bed. From the 4x10' bed we yielded 4 pounds of dry seed.

The process of harvesting/saving seed entails allowing the crop to mature to fruit followed by cutting off its water source so as to dry it. By doing so, the flowers that have not yet gone to fruit will, while those that have dry out, making them easier to remove from the inflorescence.

Once the seeds are ready for harvest, remove them, and using a screen, winnow out the smaller petals and botanical debris. Some seeds may not be completely dry so store them in a paper or cloth bag (not plastic); this prevents mildew and promotes drying.

* Above is spinach seed that was recently collected.

* Above are sunflower seeds.

So as to dry the harvested seeds and discourage molding, the seeds are spread thin over a screen and left in the sun until dry.

* Above is harvested flax.

Due to the apple press' limited ability, we constructed a much more sophisticated tool to aid in our goal of fermenting fallen apples as a means of producing ethanol.

It functions as both a grinder and a press and we were able to construct it out of basic hardware, including parts from the previous apple press (all lumber used was recylced).

The grinding mechanism was built using 3/4" steel nipples attatched to a 5" in diameter cut of fir. Screws were then distributed around the circumfrance of the wood to act as the teeth of the grinder.

The grinder was mounted by drilling 1 1/2" holes through the diagonal support beams that connect the leg posts and a handle was added for easy torque. We then added a funnel to hold the apples to be ground and added horizontally placed 2x4s to support the press.

The construction of the press was more demanding because it required that the platform be waterproof and that we provided a faucet of some sort to dirrect the pressed liquid. The platform that we made was first caulked with silicone to avoid any leaks and then coated with a sheet of galvanized steel. The faucet was made from PVC parts left over from the drip irrigation system and was installed just as the grinder was, by drilling a 1 1/2" hole within which it rested. Silicon was also used to make sure no liquid escaped around the sides of the faucet.

We are able to easily remove the press and fill/empty the contents because rather than permanently attatching its parts, they are simply clamped down before and after each pressing.

With one person opperating the machine, we are able to produce 4 gallons of liquid per hour; this includes collecting the apples, grinding them, and pressing them.

After producing eigh gallons of wort, measurements of the temperature, the sugar content, and the pH were taken.

A pH of 3.5 was measured at 78 degrees farenheit with a sugar content of 12% prior to bringing the wort to a boil.

The wort was then poured into a stainless steel kettle, and brought to a boil so as to kill any bacteria that might compete with the yeast we would soon add. By doing so we were also boiling out water, hence increasing the sugar content as well as neutralizing the pH.

After boiling the wort and allowing it to cool, yeast nutrients were added and measurements were once again taken. As the temperature of the wort cooled, the hydrometer's reading of the sugar content became more accurate. I was able to boil out enough water to bring the sugar content to 20% and the pH to 4.5. The sugar content could have even been higher and this has been noted for the next batch.

Once a temperature of 80 degrees farenheit was reached, the yeast was added, the lid was put on the bucket and the bucket was placed in a cool place to ferment for the next three days.

As the crops grow, we are racing to equip the garden with the tools required for the production of ethanol as a fuel source.

Ethanol Production

1. Fermentation

To produce ethanol from the crops that we are growing we must first mascerate and press the sugar/starch rich part of the plant into what is called the wort.

By bringing the wort to a boil in a stainless steel kettle we are able to kill off the bacteria and other microbes that would compete with the distillers yeast that we introduce once the wort has cooled down. The quicker the cooling process the better; this reduces the risk of bacteria reestablishing residence in the mixture. Once the yeast has been added the contents of the kettle are refered to as the mash. It is the mash that we add to our airtight fermentation containers and allow to ferment for 1-3 days.

Before adding the yeast it is important to check the temperature of the mixture. Yeast prefers temperatures of 80-90 degrees farenheit.

Before adding the yeast it is important to check the sugar content of the mixture. Because yeast converts about half of the sugar to alcohol (the other half into CO2) and because yeast commonly perishes in alcohol percentages of 15% and higher, it important to dillute your wort to sugar percentages of 20-30%. By adding cooled sterilized water you can quickly cool the wort while reducing the sugar content.

C6H12O6 → 2CO2 + 2C2H5OH

Before adding the yeast it is important to check the pH of the mixture. Yeast performs best at a slightly acidic pH of 4-4.5. By using lithmus paper and adding an acid or base accordingly this pH can be obtained.

Yeast can be added once the mixture meets these conditions. Allow the mash to ferment for three days before disturbing the anaerobic process.

2. Distillation

After fermentation the mash should have an alcohol percentage ranging from 10-20%. So as to obtain the higher percentages required for running a vehicle distillation is necessary. Using a reflux still, obtaining alcohol percentages up to 95% is possible. The remaing 5% water can be removed using zeolite or corn grain as a filter. Constructing a still and obtaining our experimental distillers license is the next step in our goal of producing fuel from the crops that we are growing at the Sebastopol Demonstration Energy Garden.

1. Building a Solar Oven begins with Evaluating the Tools and Materials that You Have to Work with.

* A month or so ago we had a window donated to us. Initially we were going to incorporate it into a cold frame structure however it seemed appropriate for a solar oven. All of the cuts were made in accordance with the dimensions of one of the panes which were 33.5"x26"

2. Designing the Solar Oven

* As with most structures it is a good idea to browse images of other designs; this allows you to identify features that are consistent among the designs as well as exposing you to possibilities you might not have been aware of.

* In general you can determine the angle at which to position your solar panel by:

latitude - 15o (summer)

latitude + 15o (winter)

Because Sebastopol is located at 38oN the ideal angle for incident solar radiation is 23o.

*It is also important to have in mind the positioning of the reflective panels when designing the frame of your solar oven. Make sure that you can open your oven while maintaining flexibility in adjusting the reflective panels.

3. Making Measurements, Cutting Pieces, and Constructing the Frame.

* Remember heat should stay in the oven; be precise in your measurements and cuts. Large gaps will only make it harder when it comes time to caulk.

Quantity Size Purpose

1 2"x4"x36.5 Front Refelctive Panel Attatchment

1 2"x4"x33.5" Front Wall

2 1.5"x11"x26" (angled) Side Walls

*Note: Between the height of the window pane and the heights of the back and front walls I was able to determine the measurements of the side wall and make cuts with the table saw.

1 1.5"x11"x33.5" Back Wall

4 2"x4"x11" Back and Back-Side Reflective Panel Attatchment

2 2"x4"x2" Front Side Reflective Panel Attatchment

2 2"x4"x8" Inside Supports for Back and Side Walls

2 1"x1"x15.5" Front Window Lip

1 1.5"x36.5"x28" Floor

2 0.5"x16"x36.5" Front and Back Reflective Panels

2 0.5"x16x28" Side Reflective Panel

4. Painting Black, Caulking, and Attatching the Window

* Painting the inside black assists the solar oven in retaining as much heat as possible. Using a paint with a high gloss provides a sheen that can retain more heat.

* Be sure that the caulk you are using can sustain the high temperatures that your oven will reach.

* I was lucky enough to have a window pane that I could screw my hinges into. It also came with a locking mechanism that I removed and attatched to the front wall of the frame.

5. Sealing in the Heat

*Insulating the gaps where your window meets the walls is a good idea; it will allow for higher temperatures to be reached.

6. Attatching the Reflective Pannels

* Although there are many materials that can provide the silver reflective properties that you are looking for be sure that what you choose is easy to work with. In my initial plan I had included mirrors; however, due to the fragility of glass and a need to make specific cuts, I chose to work with the reflective insulation material that is often associated with winshield solar protection. I was able to shape this to my cuts of wood easily and attatch it using a staple gun.

* Figuring our how to make your angles adjustable yet secure is tough. I used hinges for each panel and added an additional adjusting hinge to hold each pannel in place. Attatch your hinges to the previously assigned parts of the frame in a manner that does not conflict with the opening and closing of the solar oven's window.

*Note: You will probably want to install a thermometer to monitor the temperatures inside of the oven