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.

I just spent three days talking about biofuels with other scientists who work at historically black land grant universities. These institutions exist in most southern states because of an 1890 law requiring states to either set up a land grant institution for people of color or demonstrate that race was not an admission factor at their existing institution. Kentucky State University, where I work, is one of these '1890 land grants.'

The 1890 land grants are interesting because of their mission to serve under-served constituencies, including minorities and people with limited resources. The 'get big or get out' prescription sometimes associated with land grant universities ought to be an anathema to 1890 land grant universities.

This week's meeting was called to explore ways for 1890 land grants to contribute to USDA goals, including "the development of biofuels and processes to efficiently convert renewable plant products to fuel." It came at a time when food prices are skyrocketing and people are going hungry, in part because a growing proportion of America's corn is being turned into fuel.

At one point I expressed to a USDA economist my opinion that the large scale corn to ethanol program has been a complete failure, neither reducing carbon emissions, nor contributed to energy independence. The economist surprised me with his defence that neither of these were program objectives. The real goal, he said, was to raise corn prices. By that measure the program has been a resounding success(!).

After three days of intense discussion we hammered out a list of research objectives for 1890 land grants working on biofuels. They are:

1. Identify, produce, characterize and improve alternative feedstock crops.
2. Develop and optimize small scale technologies for biofuel production.
3. Evaluate and improve biofuel and byproduct quality.
4. Educate and train students, farmers, and other professionals regarding biofuels.
5. Analyze economic, environmental and social impacts of biofuel production and use.

So those are my guiding principles as I continue to participate in the Energy Farms Network and collaborate with the Post Carbon Institute. Over the summer I'll work with researchers from Virginia State University and North Carolina A&T University to pull together a full proposal, based on these objectives, for a collaborative project involving all eighteen 1890 land grant universities.

Some of my current research is funded by Southern SARE, so I took note when the organization released a position paper on the type of biofuel research it will fund in the future. SARE identifies eight themes for future projects to "expand the focus in bioenergy beyond corn- and soybean-based ethanol and biodiesel:"

1. Energy conservation and efficiency;
2. Energy efficient production practices;
3. Non-biomass renewable energy sources;
4. Alternative biomass feedstock production systems;
5. Environmental impact of bioenergy production;
6. Community and rural development impacts of bioenergy production;
7. Local and regional economic impact of biofuel production; and
8. Whole farm integrated energy systems.

It looks like the Energy Farms Network is on the cutting edge.

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• The goal is to feed more people, not fewer people. There is an old adage that has already been quoted about putting all your eggs in one basket. If I were one of those fifty people who was being fed by only one farmer, I'd be more worried than if there were four or five-or ten. Suppose the one farmer dies?
• Two and a half percent of the population is feeding all the rest. That is very small. And as far as I can see, nobody is worrying about where the cutoff point is. There is always a bottom half. We are always concerned about eliminating the bottom half because we say they're inefficient. I think that our doctrine of efficiency is suspect anyway because it only applies to major quantities. We waste stuff at our place all the time because we can't sell it. It's too little to sell. You can't give it away unless you cook it for somebody.
• How small do you let the percentage of farmers get before you are in danger? We have no alternative energy source on the farm now. When one farmer's feeding fifty people he is absolutely dependent on petroleum. When the economy shifts to reflect the realities of energy, it may be too expensive to produce some of this food; certainly at current prices.
• --Wendell Berry, 1974 http://www.tilthproducers.org/berry1974.htm

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.

Sorghum is a drought tolerant plant is similar to both corn
and sugarcane and is our highlighted energy crop at Brookside Energy Farm in Willits and
the Energy Garden
in Sebastopol. Like sugar cane the stalk is
filled with sweet juice and can be pressed to make syrup. This crop is special
because it is capable of simultaneously producing both food and biofuel and
provides stacked functions
including:

1. Grain for human and animal food

2. Juice can be extracted and converted into a high calorie
syrup

3. Juice can be directly fermented and processed into
ethanol

4. Stalks can be shredded and used as a component in
livestock feed

5. Stalks can be pressed into briquettes and burned

6. Stalks can be used as a mulch

7. Stalks can be aerobically composted

Stacking functions is
a critical concept when we begin to think about energy crops or crops grown
primarily to be used as fuel. A crop with stacked functions including (sorghum,
sunflowers, Jerusalem Artichokes) offers the farmer not just one, but multiple
uses.

As many of you have noticed, energy crops are drawing a great deal of
attention because they have the potential to be renewable, and therefore a more
reliable form of energy. However, when growing energy crops we must be ready to make
a choice for food or fuel. While natural sugar and oil are useful (if not essential), we have to
ask whether or not burning these substances is the best use. We also need to
re-think the way that biofuels are made.

Many studies have shown that the net energy gain with biofuel
is very slim, and this is especially the case when inorganic fertilizer, pesticides,
and coal or natural gas is used for crop production and processing. When you
then add the cost of transportation of these fuels from the refinery to the
pump then the carbon neutrality and energy profit is slim to none.

In response, the Energy Farm Program is experimenting with
sorghum because it is unique and has the potential to provide both food and
fuel. Furthermore, we want to contrast local, organic biofuel against the
industrial model to see if we might achieve a net energy gain by using natural
methods for soil fertility, crop cultivation, and harvest. Once processed this
crop is intended to support further agricultural activities or to be used by locally,
reducing extraneous transport and lost energy.

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

[video]

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.