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.