Winter is almost over, and with it the time for
introspection also draws to a close. The heavy rains and shorter days have given
us time to create a sign system that illustrates our priorities in the garden. In
the coming year some focuses like crop selection and soil building will stay
the same, and this season they will be enhanced by a winter of planning that we
did not have last year.

Education is also a key priority as we enter the 2008
growing season, and one of the primary tools that we developed this winter is
our garden didactic system. This collection consists of 23 concept signs and 30
profile crop signs. They will be scattered throughout the garden to greatly
enhance its accessibility.

This project was beneficial to the Energy Garden initiative
because in the process compiling the content, we were able to summarize our
work to date. In addition, the signs helped us to identify the focal points of
the garden and the methods that influence its development.

The concept signs consist of:

·
Goals of the Sebastopol Energy Garden

·
Community Compost Collection

·
The Sebastopol Energy Garden Growth Collage

·
Square Foot Gardening Method

·
Natural Farming – The “Do Nothing” Method

· Cover Crops

·
The Water Catchment System

·
Drip Irrigation

·
Culinary Herb Spiral

·
Mandala Garden: The Sheet Mulch Technique

·
Methods of Season Extension: Towards a “Four
Season Harvest”

·
Appropriate Technologies

·
Processing and Harvesting Techniques

·
Tree Guilds: Edible Forest Gardening

·
Garden Cycle Tracking

·
Ethanol Production

·
The Fractional Still

·
Recycling and Compost: Designing “From Cradle to
Cradle”

·
Chickens

·
Biointensive Concepts

·
Permaculture Principles

Each sign corresponds to something that is happening in the
garden or that has influenced its progression. There are also 30 profile crops
that we have chosen because of their ability to help us adapt to Peak Oil.
Instead of a lawn, we are selecting a great range of crops to benefit humans
and the environment. Please see http://www.energyfarms.net/node/1495 for a list
of these crops.

These signs will enable people with a wide range of
understanding of sustainability to experience a transformed suburban lawn. When
people visit this year, during our second growing season, they will be
introduced to a diversity of crops with a large variety of functions. In
addition, they will be exposed to techniques and technologies that are easy to
learn and have the potential to make a big difference in their lives.

The rains will soon stop, and spring will bring a time of
action. We will sow seeds of diversity in the garden and hopefully, inspiration
in the community. The Energy Garden is always open to visitors and we look
forward to helping more people experience the resilience of the Earth.

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]

My name is Michael Bomford. I work for the Community Research Service at Kentucky State University, an historically black land grant university in Frankfort, Kentucky's capitol city. My research focuses on developing sustainable organic agriculture systems suitable for adoption by small farmers. Check out some of the projects I'm working on here.

KSU energy farm project, with food crops (foreground),
high tunnel, and energy crops (background).

1. 1. Biointensive - using human labor and hand tools in small beds, according to the methods of John Jeavons
2. 2. Market garden - using no machinery larger than a walk-behind tractor in medium-sized beds
3. 3. Small farm - using standard four-wheeled tractors for crop production at the field scale.

Jason Bradford and I left Willits, late Thursday and set off
toward the Sacramento
valley, set to return with all the necessary equipment and supplies to initiate
the Dryland Grain demonstration with ET-7, a scratch-built electric tractor. We
had a strong truck and an eleven foot long trailer that would be able to carry any
implement we found that would be appropriate. As you may know, the Sacramento valley is considered to be the northern heartland
of California
agriculture. Thus, it is rich in used agricultural equipment and plenty of
conventional wisdom related to various large-scale agricultural operations.
Before setting out, we had spent the week calling various grain distribution outlets
and equipment dealers, trying to narrow the number of stops on our trip.

There are many options for a farmer as they “open the field”
(i.e., begin to turn over the soil for the first tilling and planting). Typical
practice includes using a moldboard plow that is capable of turning over soil
at a depth of about 14 inches, using a roto-tiller to incorporate and shred the
first 4-6 inches into a fairly fluffy and uniform seedbed, and using a single
ripping tooth to dig and rip into the soil from 8-36 inches. Each of these soil
cultivation practices are energy intensive and disruptive to the microbiology
in the soil. The PTO driven roto-tiller uses much of the available horsepower
from a tractor and runs at a high RPM, burning diesel and shredding microbes
and organic matter in its wake. The moldboard plow runs deep into the soil, uses
a fair amount of energy as it flips the topsoil to the bottom thereby
disrupting natural soil strata and creating a plow-pan. Finally the ripping
tooth requires multiple passes, again disrupts the fungal web of the soil, and
requires more diesel energy the deeper you go.

In light of these observations we have chosen to use a
disc-harrow to open the soil. This implement will be used to penetrate the soil
4-6 inches and incorporate sod and organic matter gently into the land. While it
may not be as effective in the first pass as a roto-tiller or moldboard plow,
it is a long-term practice that will eventually cut into the land gently without
making a drastic hard-pan, severely disrupting the biology, or utilizing
significant energy from the tractor to prepare a seedbed

Since we are working with an electric tractor (an admittedly
rare item) we had a difficult time getting any clear answers from equipment
dealers as to what the actual size of the disc they would recommend. As you
might expect, there was not a lot of experience in the field of electric
tractors. We, therefore, had to do the math for ourselves. I knew from my conversations with Steve Heckeroth that the
tractor with two 2Hp electric hub motors, geared at 50:1 ratio would have
enough “guts” to pull any heavy implement, but we wanted to find the appropriate
sized implement or we would not be making efficient use of the on-board battery
banks. Sure, it could pull something big, but if it drained the battery too
fast what good was the implement. In fact, over-sizing the implement is one of
the biggest wastes of energy with tractors in agriculture and also limits a tractor's life expectancy.

The key for the electric tractor is to run slow. The slower the machine runs
the deeper the disc will sink into the ground. Also the slower the machine runs
the more drawbar horsepower (ability to tow) will be available to the implement. The Drawbar
horsepower needed to pull an implement is given by the weight of the implement (including
the average pounds of force applied per disc in the soil) F and the speed that the implement is pulled through the soil S. The equation to find the necessary
horsepower to pull an implement is FS/375.
Each 18 inch disc is about 38 pounds of weight load into soil and most
disc-harrows have 16-20 discs. Initial test data related to ET-7 suggested that
it could provide 20Hp of continuous operation with a tops speed of about 8 MPH. This was our goal; match a disc
to operate smoothly at around 20Hp. We found a 5 foot wide disc-harrow that
had 16 blades and weighed 628 pounds. To see if this disc would fit we
performed the calculation described above:

F= [628 pounds + (38 x 16)] = 1236 pounds S=6mph

1236 x 6=7416 7416/375=19.78
Hp required to pull implement

Ok, so now we had the range. We called some dealers and
looked on craigslist for used tools and made our way toward the Sacramento Valley. We checked in at Woodland
Tractor. These gentlemen were friendly, but unfortunately they did not have the
any implements that would be ideal for our application. We told the salesman
that we were headed to Grass
Valley for the 2^nd
Annual Sierra Nevada Small Farm Progress Day and he suggested a dealer in that
town. We thanked him and made our way to the Small Farm Progress Day.

When we arrived at the Small Farm Progress Day, we saw the
Electric Tractor on display. This convention was to demonstrate and showcase
tools suited to small farms and included horse drawn equipment, small scale implements,
and food and livestock production workshops. We manned the Electric Tractor
booth with Steve Heckeroth and used the opportunity to talk about issues of
energy usage in the total food system, localized food production, and the way in which
the electric tractor confronts the food vs. fuel issue. Overall it was a fun
day and we felt proud that while many people got to look at the machine, we
were the folks who would begin to put it through its paces.

After the Small Farm Progress Day we visited the local equipment
dealership in Grass
Valley. They had a 4.5
foot Gearmore disc-harrow that weighed about 480 pounds and had 16, 18 inch disc-blades. Given the equation we worked above:

F= [480 pounds + (38 x 16)] = 1088 pounds S=6mph

1088 x 6=6528 6528/375=17.4
Hp required to pull implement

This disc seemed to be well within the acceptable range for
the size of the implement we are using. Like the disc, the measurement to the
outside of the wheels is 4.5 feet wide. Pretty close to a perfect fit. Since
this disc is so light we will have to find a method to add a little weight over
the blades. To do this we will add scrap steel and/or a water tank to help
drive the blades deeper into the soil. With the disc on the trailer we were off to Adams Grain Company to pick up wheat seed.

--Want to learn more about sizing farm impliments click here

--Want to learn more about tractor horsepower and torque click here

Steve Discussing ET-7 at the Small Farm Progress Day in Grass VAlley, CA

Small Scale Farmers Looking on at ET-7 Workshop

Gearmore 4.5 Foot Disc-Harrow (Semi-Stubble)

Front View of the Disc-Harrow Loaded on The Trailer

While a bulk of the focus in 2007 has been to establish an Energy Farm
Demonstration Site at Brookside Elementary School, in Willits, CA; we realize
that intense vegetable production is a piece of the larger picture in the
attempt to reduce the high
energy inputs to the food and agricultural system. In addition to building
and testing post-petrol tools and methodologies for intense vegetable
production we are duly interested in conducting research and developing
templates for grain, oilseed, and livestock production. As always, farm
products will be produced locally for local consumers with the aim of
promoting both local food and energy security.

This been said, I would like to share a project proposal
titled: Steps toward Local Food Security—Little Lake Valley Grain Production.
We have been shopping this proposal around the community of Willits and many
people seem interested in fostering the development of a local food system and
very excited about the tools and methods we seek to employ.

Steps toward Local Food Security—Little Lake Valley
Grain Production

WELL, and other local
organizations, have undertaken several studies
and workshops on local food security in the 95490 zip code, with a population
of approximately 13,500. Based on historic production data, a key initial
conclusion of one study suggests that if a localized agricultural system
would grow a diverse supply of food for this population, then
approximately all of the 4000 acres of prime agricultural land in Willits would
be needed for crops. Research noted
both a demand and supply gap related to local grains. Also lacking is the
processing and storage equipment needed to carry out successful grain
operations.

In response to this
research, we are seeking 3-6 acres in the Little Lake Valley to perform a
dryland (i.e., non-irrigated) grain demonstration. This project seeks to
“Ground-Truth” a number of assumptions related to yields, time investment,
labor, required tools and infrastructure, and consumer relationships as they
pertain to localized grain production. A dryland grain demonstration is
important to local food security because grains have high caloric value, ease
of storage, and can be grown in a manner that does not rely on energy dependent
irrigation infrastructure.

We will test an electric
tractor, whose recent repair is being provided by the Post Carbon Institute, to
sow grains. This tool is not only quiet and light on the environment (little
greenhouse gas emission), but it easy to drive, powered by renewable energy,
and is assembled in Mendocino County. A
special feature of the electric tractor is that it is capable of powering many
small electric devices in the field such as portable threshers and winnowers.

Key project goals include:

- Test Steve Heckeroth’s ET-7 electric tractor at a
significant scale

- Deeply investigate the methodology of dryland
cultivation

- Re-invigorate and strengthen agricultural
relationships in the community

- Inspire community members to support a local food
system

- Enroll youth and experience into the formation of a
local food system in Willits

- Save seeds for the most successful varieties of oats,
wheat, barley, and triticale

- Test the effect of companion planting and the use of
mycorrhizal fungi in small grain production

- Demonstrate the opportunities to create localized
agriculture within the United States
and create templates for replication

- Watch for vulnerabilities in agriculture in relation
to future energy scarcity and global climate change

To fulfill the aims of this project we are looking to secure the following resources:

- Land --We
are seeking 3-6 acres suitable for agricultural development (Class I or II). No
irrigation infrastructure is necessary for land to be approved for the project.

- Equipment --
Much of the equipment we need already exists in Willits and may not be fully
utilized. If you want to lend, donate, or trade for the use of a disc, harrow,
and/or a seeder we would be very interested in cooperation.

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.

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 discourse has been heating up around biofuel for well over a year now. The classic food versus fuel debate has been engaged recently by the United Nations, while scientists, climate change experts, and farmers begin to question the scale and logistics of biofuel replacement of the current liquid fuel demand.

This June, one of us (Dr. Jason Bradford) interviewed Lawrence Berkeley National Laboratory staff scientist and Post Carbon Fellow David Fridley on the bi-weekly radio show the Reality Report. The topic for the interview: “The Myths of Biofuels” finds Bradford and Fridley engaged in a devastating analysis of the scale and logistics of replacing our current fossil fuel demand with ethanol and biodiesel. In short, a large scale industrial biofuel system will wreak havoc on the soil, require an entirely new distribution infrastructure (due to the corrosive nature of ethanol), not easily adapt to the current fleet of USA autos, will compete heavily with food production and natural ecosystems that are seen as potential cellulosic biofuel feedstocks, and will do little to actually replace the current (or future) energy demands of liquid fuel.

Two weeks later, the Reality Report picked up where the Fridley show left off and we both joined Yokayo Biofuels President, Kumar Plocher on the show. The question was: If biofuel is not going to be sustainable on a large industrial scale, then would a local biofuel system be an appropriate response to the limitations of long-distance transport and petrol dependent methods of cultivation and processing of biofuel? If biofuel is produced for local consumption how much land would be needed, what crops would be used, and how would they be processed? Again, simple math painted a picture of an inflated hope and hype. We ran the numbers and with the 35,000 acres (14,000 hectares) of remaining prime farm land in Mendocino County approximately 84,900 acres (34,000 ha) would be needed to replace current county diesel consumption if canola was used as the prime feedstock.

Additionally, approximately 231,100 acres (94,000 ha) of farm land would be needed to replace the current gasoline consumption with corn-based ethanol. It doesn’t really matter much which crops, or combination of crops, are considered--the land base isn’t available to support a biofuel industry even on a local scale that meets current fuel demand. These analyses also absurdly assume the use of all agricultural land for fuel production, leaving no room for food! This is unconscionable and not the direction that any serious farmer or environmentaly aware person desires to advocate.

As the hype around biofuel already begins to dissipate, serious researchers and planners are advocating curtailment of long distance transport and the adoption of electric vehicles as one of the most sustainable options to replace the work and carbon footprint of the internal combustion engines. Vegetable oils and ethanol are useful products and should not be omitted from agricultural production, but their uses require further consideration. Why do we have to burn these useful feedstocks when they have multiple alternate uses? Should biodiesel production be limited to the reuse of waste food oil?

In an article published by AlterNet, David Morris from the Institute of Local Self Reliance makes two important observations related to the uses of vegetable oils and plant-based sugars that are consistent with the position of the Local Energy Farm Program. Morris suggests that

“human nutrition is the highest use of plants, followed by medicinal uses and possibly clothing [and…] we should first use biomass to substitute for industrial products that use fossil fuels rather than for the fuels themselves. [W]hile there is insufficient biomass to displace a majority of fuels; there is a sufficient quantity to displace up to 100 percent of our petroleum and natural gas-derived chemicals and products. And these are much higher value products.”

Additionally, he recognizes that: Electricity, not biofuel, will be the primary energy source [note: we consider electricity an energy carrier, with wind, solar radiation, etc. being renewable sources] for an oil-free and sustainable transportation system. But biofuel can play an important role in this future as energy sources for backup engines that can significantly reduce battery costs and extend driving range.

While biofuel might remain a short-term transition technology, it is being recklessly advocated by the United States Senate as a panacea for the liquid fuel appetite. One response is to advocate appropriate uses of biofuel, including its role in agriculture. Another is to adapt to new information and seek alternate ways of powering crucial societal infrastructure. One such component is a relocalized agricultural system.

We should remember that biofuel was originally produced by farmers for on-farm use. Just because you can power an internal combustion engine on bio-blends does not necessarily mean that it is a suitable energy replacement or clear cut solution to salvage the industrial model which is so deeply dependent on cheap liquid petroleum.

Before agriculture began to juggle the burdens of constant soil degradation, increased mechanization, and cheap labor (see Steinbeck’s ‘Grapes of Wrath’), animals were used for the cultivation of crops. However, like a biodiesel tractor, some land must be dedicated to feeding a team of horses. On good pasture land it is estimated that 5 acres (2 ha) of land is needed per horse. Marginal land could require about 13 acres (5 ha) per horse, and possibly much more.

Similarly, to produce 1000 gallons (3,800 liters) of biodiesel requires the cultivation of 10.25 acres (4 ha) of canola. This is assuming you have access to processing equipment and methanol (which is normally derived from natural gas). Whether you consider horses, oxen or biofuel to reduce dependence of fossil fuels, cropland is used that will often compete with land needed to grow food.

For example, data from the Nebraska Tractor Test Laboratory shows that the performance of small, modern tractors at around 20 hp requires about 1.7 gallon (6.4 liters) of diesel fuel per hour of work. If we estimate that a tractor will be in use about 1000 hours per year, this would require 1700 gallons (6,400 l) of fuel. In biodiesel terms, it would take 17 acres (6.9 ha) of prime crop land to grow the fuel for one small tractor per year. Of course we should also think about how much land such a tractor could cover in a year. A small tractor could cultivate about 25 acres (10 ha) in those 1000 hours, meaning that after fuel crop use only 8 acres (3.2 ha) would remain for non-fuel crops.

Post Carbon Institute’s Energy Farm Program is addressing the tension between food vs. fuel, or land vs. energy. In our search for ways to reduce these tensions comes the latest Energy Farm Demonstration Project: The Electric Tractor.

We have made connections with activist and inventor Stephen Heckeroth and are seeking to test cutting edge agricultural equipment for a post-petroleum world. The electric tractor does not compete for food and prime agricultural land for fuel, has a significantly reduced carbon footprint, increases the scale of acreage that can be cultivated, and is easy to operate for the 50 Million New Farmers that Richard Heinberg is calling for in the coming century. Stephen is not the only person who has made the electric tractors. John Howe has been working on retrofits of agricultural equipment powered by electricity.

This week we took a (petroleum-powered) scenic drive through the redwoods to the Mendocino coast to visit Stephen Heckeroth and demo his “Solar Electric Tractor.” Stephen has been working on alternatives to fossil fuel use in both his private and professional life since 1970. His company, Homestead Enterprises, has been doing electric tractor conversions since 1993, and has become an internationally recognized consultant on industrial and agricultural electric equipment. In 1996-97, Ford-New Holland commissioned Homestead Enterprises to build an electric tractor prototype. In 1997-98, a Japanese company, Eifrig Ltd. Commissioned another prototype. A fully functional design was completed in July 1998 and several provisional patent applications were filed in August 1998.

As Stephen points out: Our future is only as sustainable as the tools we use to get there. The daily energy income from the sun is gigantic and it is feasible to use already existing renewable energy infrastructure to “re-fuel” the Electric Tractor. If the farm has yet to invest in renewable energy infrastructure, it is also possible to charge the batteries with standard 110V power (or 240 volts in other parts of the world).

Let’s run through some numbers to help us evaluate the land requirements of electric tractors versus tractors operating with biofuel. Electric motors are about 90% efficient at converting energy to work, and solar panels are the most efficient way of converting radiant sunlight energy into electricity (approaching 20% vs 1% or much less for plants). Stephen’s tractor can hold 5 kWh of battery packs that will give the same kind of performance in terms of work over a year as the 1700 gallons of diesel fuel in a small tractor. 5 kWh of batteries can be recharged each day with a 1 kW photovoltaic system covering about 40 sq ft (3.7 sq meters) of roof space. By contrast, 43,000 sq ft (4,000 sq m) are in an acre (which is 0.4 hectares).

In terms of fuel dollars, 1700 gallons of diesel cost about $5,100 in 2007. Installing a 1 kW photovoltaic system might cost about $10,000. By investing once in double the annual cost of fuel, a farmer could power a tractor for decades.

Not only does this appear to be an economically wise investment, but electric tractors are a pleasure to use. As you would expect from an electric motor there is no diesel exhaust emissions and no loud engine noise. While driving the tractor we could actually hear birds chirping (a rare experience when operating heavy machinery). With an electric tractor there is no longer a need for engine oil or oil filters, a radiator and coolant, no need for fuel filters, no engine overhauls, and it offers a lower operating cost ($0.50) to charge the 5kWh battery pack. There is a 1500W charger/inverter on the tractor and a complementary AC power outlet. This is a useful feature because it allows the use of electrical equipment in the field (e.g. sorghum press, or thresher and winnower). The ability to process certain crops in the field (like sorghum) is a good way to circumnavigate the need to transport large amounts of material to a central processing facility.

We plan to put the tractor through its paces and provide data that farmers will find useful as they begin to evaluate the efficacy of this exciting technology. Although in theory we should have great performance from an electric tractor, a lot of questions exist related to how long the tractor can work (similar to the range of an electric car) and whether or not the machine has enough power for the rigorous demands of cultivation. To test the machine we will attempt to run a dryland grain demonstration in Willits, CA. We intend to plant a fall crop of wheat or oats using a disk, harrow, and seeder. These classic implements used to be horse-drawn and do not require the intense energy that PTO (Power-Take-Off) implements require (less draw-down on the battery bank). The over-winter rains will help to get the crop established without relying on intensive irrigation and we plan to come back in the next summer to harvest and process the cereal crop. The experiment is two-fold in which we get a chance to demonstrate and produce grains with minimal amounts of fossil fuel and high energy inputs while also collecting data related to operation time and power capacity of the prototype electric tractor.

Aside from John Howe and Stephen Heckeroth, we have not heard of other people using electric tractors for other than mowing; we hope that many are out there. We would like to hear from you. We invite readers to check our numbers and the assumptions above and please tell us how realistic we are, based on your data, calculations and experience.

If you want to see Stephen’s tractor in operation, check out this link.

For more information about the Willits/Brookside Energy Farm and about the electric demonstration, please contact Dr. Jason Bradford or Christoffer Hansen.

For more information about the Energy Farms Program, please contact Julian Darley, President Post Carbon Institute (email or call 1 800 590 7745)

Electric Tractor Front View

Jason Testing The Front Suspension on a Hill

1500 Watt Charger/Inverter with Battery Bank (Mounted Over Rear Tires)

AC Power Outlet to Use Tools In the Field