A startup company called EFuel100 is taking orders for its new MicroFueler, an energy-efficient fermentation, distillation and dehydration system that turns sugar and water into ethanol.

The MicroFueler is the brainchild of Floyd Butterfield, who designed the award-winning Butterfield still back in 1980. The Butterfield still was designed for farm scale, energy-efficient ethanol production from carbohydrate-rich crops. 250 acres of corn could keep it going for a year. (Most new ethanol plants need about 200,000 acres of corn to operate at capacity for a year.) Although a modern ethanol plant gets about 15% more ethanol from each bushel of corn than the Butterfield still (2.7 vs. 2.3 gallons/bushel), Butterfield's system was more compatible with small, diversified farming operations, and didn't require long-distance trucking of feedstock.

With the MicroFueler, Butterfield takes the "small is beautiful" philosophy one step further, aiming to bring ethanol production from the farm scale to the home scale.

The MicroFueler makes fuel out of sugar, which is food. Most large-scale conventional ethanol plants start with starch, which is food. The first step in their process is to break down the starch into sugar for fermentation.

The holy grail of current ethanol science is the production of ethanol from non-food, high cellulose materials, like switchgrass or corn stalks. The major barrier to most cellulosic ethanol production is the development of efficient means of breaking cellulose down into sugar for fermentation. In other words, to make ethanol from non-food crops we're trying to figure out how to turn them into food. Whether the sugar comes from starch or cellulose, all fermentation starts with sugar.

Sugar is the building block of life. Photosynthesis is the light-driven reaction that makes sugar and oxygen from carbon dioxide and water. Organisms digest sugar to get energy, turning it back into carbon dioxide in the process. Plants store energy in the form of starch, which is a long string of sugar molecules that can be broken down relatively easily. They also make strings of sugar molecules into cellulose, a structural material that doesn't break down easily, and is found in cell walls.

Even if you aren't a chemist you can probably tell from the figure on the left that starch and cellulose are made from the same stuff. The molecule in the square brackets is glucose, or sugar.

The promotional material for the MicroFueler claims it will make a gallon of ethanol from about 12 pounds of sugar. For the past decade 12 pounds of unrefined sugar on the world market has cost about 30% less than a gallon of gasoline in the US. Between 1976 and 1996 a gallon of gasoline generally cost about 15% more than 12 pounds of sugar. Today's commodity investment advice? Buy sugar.

According to the promotional material (pdf), the MicroFueler "solves the ethanol transportation issue by containing the refinery and pump delivery system within the same system – in other words, people can produce where they consume, using the MicroFueler to both create ethanol and pump their vehicle with fuel."

Since the Energy Farms Network is based on the premise of local resource cycling and local production, I was curious to estimate the land needed to produce enough sugar to use the MicroFueler to run my car. Last year our sweet sorghum crop gave us about three-quarters of a pound of sugar per square yard. Each gallon of ethanol, then, would require about 16 square yards of sweet sorghum to be harvested, juiced and fed into the MicroFueler. Ethanol has about two-thirds the energy density of gasoline, so I might expect my Toyota Corolla, which gets about 37 miles per gallon of gasoline, to get 25 miles per gallon on ethanol. To drive it 10,000 miles per year I would need about 400 gallons of ethanol, or about 1.3 acres of sweet sorghum.

That's about 8 times more land than I have in my backyard. I guess it's back to my bike...

Michael Bomford provides research and extension services related to organic agriculture and farm-scale renewable energy production through Kentucky State University's Land Grant Program.

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.

[video]

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

----------------------------------------------------------------------------------------

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.

[video]

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.

The figure below illustrates the way in which a common chipper/shredder can be converted into a small scale threshing machine. This conversion is 1 of 9 gifts to humanity from the work Allen Dong of I-Tech Designs: PO Box 413, Veneta, OR 97487. Allen Dong's Appropriate Technology for Small and Subsistence Farms is archived here on a UC Davis website.

This invention was declared public domain August 1994, and was demonstrated at the Washington State University Vancouver Research and Extension Center. Click here to check out the Washington State demonstration, complete with explanations.

In order to help salad greens store better after washing it is necessary to remove as much excess water as possible before placing them into cold storage. Without electricity at the site, I had fun trying to replace a "spin cycle" with a milk crate and some twine. I was trying to replicate the practice in which some small scale farmers wrap salad greens in a cloth blanket and placed them into an old wash machine on the spin cycle. They do this in order to fling extra water from the greens and allow them to be bagged or stored for later use and distribution. This is an important step in processing greens because the CSA subscriber or market does not want to pay for the excess water weight and the greens will wilt and become slimy if bagged wet.

Although this process works well on the very short term and small scale, it may be too dizzying to do constantly. If I find the time, it would be great to create a pedal-powered spinner to do the job.

20 LBS of Lettuce

Rinsed and Fluffy Greens