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Discussion Starter · #1 ·
Here is an interesting article from Global Public Media.

The Case for the Electric Tractor

30 Jun 2007
The Case for the Electric Tractor
Christoffer Hansen and Jason Bradford
Post Carbon Institute - Energy Farms Program

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

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=85] 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

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

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

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

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)

-- =

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· Registered
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Discussion Starter · #2 ·
I worked with Steve Heckeroth for two years. Here are some photo galleries
of the electric tractors we worked with-

Steve's website-


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