by Jim Coate
|Note: This article was originally
written for and pulished in
The Natural Farmer,
the newspaper of the
Northeast Organic Farming Association (NOFA).
Copyright 2003, The Natural Farmer. Reprinted by permission.
I've often thought that electric tractors, and electric machines in general, would be a great match for the small farm. Somehow using petroleum fuels while taking good care to not use synthetic fertilizers doesn't seem quite right (at least from the comfort of my chair). Some have avoided this issue by using draft animals or by fueling their machines with biodiesel, but out of necessity many use either gasoline or regular diesel in their Internal Combustion Engines [ICE for short].
The down side of petroleum fuels is often discussed the environmental impacts of extracting and burning it, the societal costs of "protecting our interests" in distant countries, and so on. I'm also not that found of working on greasy engines, and now drive an electric pick-up truck.
Electric vehicles, tractors, and other machines are clean, simple, and quite to operate, and arguably cheaper in the long run. But wait, where does that electricity come from? If you get your electricity from "the grid" (local electric company) then yes, somewhere, someplace, in someone else's backyard, coal or oil or natural gas is being burned or a nuclear power plant is splitting atoms to make your electricity. Various studies have analyzed this issue, and the bottom line is that less fuel is used and less pollution is generated by the electric power plant. Think of it this way the power company generally keeps their equipment in top shape and (with some nudging) have installed sophisticated pollution control devices. That 10 year old ICE car or 30 year old ICE tractor just doesn't follow the same standards, and that ICE powered log splitter follows almost no standards.
What I like most though is that electricity can come from many other sources as well local sources that you directly control. If not for cost, anyone could put solar panels (photovoltaics) on the roof. Those who are in the right location can also use wind or small-scale hydropower. If you are on the grid, you sell power back to the electric company when you have extra and buy when you need more, but at the end of the year you have generated as much as you used. If you are off-grid, then you need to maintain battery banks to store power for when the sun doesn't shine and the wind doesn't blow. Either way, once set up you have your own source of clean quite power. It may be expensive up front, but you know where it comes from.
Plenty of electric tractors have been made over the years. A late 1800's Scientific American article showed farm tractors in South America being run on electricity from overhead wires, cultivating large fields. More recent versions, built for college research projects or in regular production, are all battery powered for greater independence. The extra weight of batteries and low-end torque of electric motors are great features for a tractor. Electric motors don't waste any energy when you aren't moving and the torque is greatest when you first start moving, right when you need it the most. As a result, electric tractors are known to beat the gassers in tractor pulls. I own a 30-year-old "Elec-Trak" and have been very impressed by its performance (see next section).
Electric tractors for towing and for lawn care are fairly easy to come by, with several models now on the market. The larger electric machines, with 10-15 horsepower motors can rival the power of a small cultivating tractor and be used for a variety of agricultural purposes. They are generally limited more by traction and ground clearance than by strength (www.econogics.com/ev/evtools.htm).
One of the more versatile electric tractors in production is the "Electric Ox" manufactured in Canada. Available with a limited selection of accessories, it can mow, sweep, grade and plow. It can tow any cart, spreader, or other implement with a standard hitch socket. With some creative welding, it could likely pull any sleeve-hitch ag implement as well. The Ox has a top speed of 5 mph, a fiberglass body over a steel frame, dual motors, electronic speed control with regenerative braking, uses 6 deep-cycle golf cart batteries, and weighs 760 pounds. It can mow for about half a day on one charge or tow for up to a full day, depending on the load. The tractor alone costs $6400 - $6800 depending on the model, and accessories are extra. The manufacturer reports that their dealers in British Columbia have been active in the local organic market (Electric Tractor Corporation, 877-533-4333, www.electricox.com).
The "Gorilla EV", made in California, is a cross of an ATV and a mini-tractor. It seats two and can tow carts and spreaders. The optional pin hitch accepts garden tractor attachments with 1/2" and 5/8" pins. It uses a series-wound motor geared for a top speed of 12 mph, and a peak power of 9 horsepower. With 3 batteries to power it, the range would be somewhat less than the Ox, but easier to recharge from an off-grid system. Similar to the Ox, it has a plastic body over a steel frame, uses an electronic speed controller, and weighs 550 pounds. The utility vehicle version costs about $5800 and is shipped directly from the factory, fully assembled and ready to drive. Additional information can be found in the February/March 2003 issue of Home Power magazine, which reports that the majority of sales so far have been to small farms (Gorilla Electric Vehicles, 714-377-7776, www.gorillavehicles.com).
A dedicated electric asparagus harvester is made in Italy. These machines are designed so that the driver sits low to the ground to easily reach the plants, and provides shade with a canopy overhead. Some may recall seeing one of the green asparagus harvesters on display at the 2001 Summer Conference. The designer's calculations show it costs a third as much to operate as a gas tractor per harvest season of 33,000 pounds. At a cost of about $5000, I'm sure it would be justified on a large operation but of limited use on smaller, more diversified farms (Bagioni Alfiero, +39 543 702182, www.asparagus.it).
Made specifically for golf course upkeep, the "E-Plex II" is an all-electric greens mower. It is sold under the Jacobsen and Ransomes brands for about $16,000. It is advertised as having a range of 15 to 20 greens per charge, depending on the terrain. It is made in Europe, but can be found in the US, and at substantially lower cost if used (Ransomes Jacobsen, +44 (0) 1473 270000, www.ransomesjacobsen.com).
Over the years, people have converted various tractors to electric, including the older Farmall Cadet, Allis Chalmers G, New Holland, and Massey-Harris machines. If you are somewhat mechanically inclined, and choose a tractor that has the engine separate from the frame, it wouldn't be too hard to round up some golf cart parts and convert your own. When a three-point hitch is needed, a second electric motor can be added to drive the PTO at constant speed. This would be a great way to get a larger machine that can navigate rough ground.
UPDATE (AUGUST 2003): Ron Khosla, a small-scale organic farmer in New York state has converted an Allis Chalmers G to electric and told me "Our electric 'G' is absolutely the most important tractor on the farm. It has three times the power of the original 'G' which is huge and [has] enough battery life to do everything we need to on our diversified 8-acre farm. [...] It's totally silent. You can creep along MUCH more slowly than we could with gas. It's silent. It doesn't smell. It's NO MAINTENANCE. [...] "It also has changed the way we operate the tractor. This is a psychological thing, but it's real. With the gas tractor, we were less likely to stop in the middle of the row to adjust things, or clean a shoe, or whatever. With the [electric] tractor... somehow there is psychologically less inertia... And we stop ALL THE TIME to make final adjustments which has resulted in a better job. When you stop, you are stopped. No engine running. It's just quiet and silent, no cloud of white smoke drifting over your head... nothing... Perfect silence. THIS is what sustainable farming is supposed to be about!." His initial conversion was fairly simple, using a common series wound DC motor, golf cart controller, and regular lead-acid batteries. After learning the hard way how to care for the batteries, he has added meters, deep-cycle golf-cart batteries, and a better charger. He is planning to do a second conversion as part of SARE grant, which will include documenting the process via a web site.
After converting a Yanmar tractor to electric, Steve Heckeroth worked with Professor John Fabel (of the biodiesel 'G' fame) at Hampshire College and several major manufacturers to make a prototype "Solar Tractor". It was designed as a multi-purpose farm tractor, with a solar panel canopy that helps recharge the batteries while providing shade. It has up to 60 horsepower at peak, and includes a Category I three-point hitch and PTO. He predicted a cost of $15,000 - $25,000, but has never gone into production (Homestead Enterprises, 707-937-0338, www.renewables.com).
I have an Elec-Trak E-20 which can do a surprising amount of grunt work. I have used mine with a tiller on back to break up heavy sod and a blade on front to push the dirt around. Although tricky in the corners without a bucket, it still did an impressive job re-grading the area. I've read about other owners winning tractor pulls (1750 pound load), towing cars, and hauling logs with their ETs. One ET owner reports being able to pull a filled 160-bushel grain wagon (8000+ pounds) on level sod as long as he didn't try and turn at all. It seems that 1000-2000 pounds, or about 200 gallons of water, is the practical limit for towing on mostly level ground. It is rare to stall the motor, although it is easy to do a wheelie, lifting the nose off the ground when there isn't enough weight on the front of the tractor.
The Elec-Traks were made by General Electric in the 1960's and 1970's, and then sold to Wheelhorse who continued producing them for a few years. Although no longer made, many can still be found used, most often with a mowing deck or snow thrower. The cost can be a few hundred dollars and up for a running machine, depending on condition. Replacement parts and manuals are still available from Bill Gunn in Wisconsin (Technical Service & Parts, 7898 North Pineview Drive, Edgerton, WI 53534, 608-868-6220).
The E8m, the smallest model at 500 pounds, uses three batteries and is basically a riding mower rather than a tractor, good only for lawn mowing and light plowing. It produces up to 8 horsepower and travels up to 4 mph, and is rated for up to 1 acre of mowing per charge. The E10m and larger models all use six deep-cycle golf cart batteries. The E10m is the middle of the line, with greater range but still limited accessories and uses.
The large frame tractors (E12 through E20) have beefy permanent magnet or sep-ex DC motors and can produce 12 - 16 horsepower or more. This allows the use of a huge variety of accessories, such as mowing decks and reels, snow throwers, dozer blades, V-blades, tillers, sweepers, bucket loaders, fork lifts, and of course carts and spreaders. A line of small accessories including a drill, hedge trimmer, cultivator, chain saw, and even an arc welder were made to plug into the 36 volt accessory outlet. These larger tractors weigh in at 800 - 900 pounds, reach speeds of 6 - 9 mph, and can mow up to 3 acres per charge or till up to half an acre per charge.
For heavy pulling of ag implements, an optional sleeve-hitch bracket is mounted to the rear of the frame, and an optional rear lift controls the height. GE originally partnered up with Brinly-Hardy for the disc harrow, row crop cultivator, tiller, and other ag implements. All of these, except the tiller, are still available new today (Brinly Hardy, Inc., 800-626-5329, www.brinlyhardy.com).
The Elec-Traks all use contactor controllers, rather than electronic controllers. This is basically a series of relays and resistors to give 3 to 8 speeds. The large frame models have a 4-speed transmission, for 12 to 24 total speeds available. After years of neglect, the electric circuits may need some cleaning up, but the parts are relatively inexpensive to replace. Some owners have retrofitted their tractors with more modern, and more expensive, electronic controllers so as to gain finer control of the speed and greater reliability.
All the models have steel frames with sheet metal bodies. After 30 years, most will show some rust, particularly around the battery boxes. If too severe, replacement sheet metal parts are available from Bill Gunn.
If you do get a hold of an Elec-Trak, make sure to track down an owner's manual and service manual, as these will provide invaluable tips for keeping the machine going. If you have internet access, there is an Elec-Trak owners club web site with lots of information and for-sale listings (www.elec-trak.org) and there is an e-mail discussion list with plenty of good advice (groups.yahoo.com/group/elec-trak).
OTHER ELECTRIC MACHINES
For a small operation, or a big home garden, there are some other interesting choices. The "Sun Horse" is a walk-behind electric machine that can plow, seed, cultivate, and haul. The battery is recharged by a small built-in solar panel or, I assume, can be plugged in for a faster charge. The variable speed drive provides much greater control than an ICE tiller, allowing for "surgical weeding" as designer Tom Lopez described it to me. He also told me of one CSA where the subscribers enjoy using the Sun Horse. The base price is $2300, or up to $4700 for a complete package with all accessories (Free Power Systems, 303-651-3184, www.freepowersys.com).
UPDATE (AUGUST 2003): During the NOFA Summer Conference we viewed a short video demonstrating the Sun Horse. Based on the audience reaction, this machine may not be for everyone. I would suggest requesting a copy of the video from the company to decide for yourself.
If you are working near enough to your house that you can run a long extension cord out the back door, there are a variety of corded tools (and even a Caterpillar bulldozer) that can replace their ICE counterparts. These include fairly common tools such as 14" and 16" electric chain saws made by Remington, McCulloch and others. Remington also makes a 10" wide, 2 horsepower walk-behind corded electric tiller called the "Garden Wizard" (www.desatech.com/remington/home.asp).
A variety of electric chipper/shredders are available, such as the McCullough MCS 1400 (www.mccullochpower.com, 800-521-8559). However, these are only good for leaves and small branches. If you need to grind up major branches, the only electric option may be to convert an ICE chipper yourself. To split wood, the "Super Split" is available from a Massachusetts company in several versions with 1 to 3 horsepower farm duty rated electric motors. These wood splitters use an ingenious flywheel system rather than hydraulics for greater speed and strength. (GFX Corporation, 508-427-5800, www2.shore.net/~logsplit).
If you already have an electric tractor, you can add an inverter and plug in any regular 120-volt AC tool where ever you go. For a small drill or a weed whacker, it is easier to just get the cordless version that has its own built in battery. When you need a larger hammer drill or chain saw, it is great to be able to power it from the tractor's battery.
Inverters need to match the voltage of your battery pack (36 volts for an Elec-Trak) and the power of the tools you want to use (1500 watts would handle most tools). The inverter needs to be rated to provide the surges required in order to start a motorized tool. Rotary inverters (basically a motor and alternator in one unit) are very robust and have been around for many years but aren't as common any more. Electronic inverters, readily available form any renewable energy dealer, are generally smaller and more efficient than rotary inverters, but a bit more expensive. The Elec-Trak was originally available with a rotary inverter and the Electric Ox is available with an electronic inverter as a factory option.
There are a variety of electric vehicles such as my electric pick-up truck that could be useful on a farm. On-road vehicles range in size from small one-person pods to full size city busses. And yes, there are people who specialize in go-fast electric cars (National Electric Drag Race Association, www.nedra.com).
For $4000 to $9000 you can find a pickup truck that has been converted to electric or convert one yourself using several kits that are available. By keeping the number of batteries down, this could be useful for hauling larger loads around your own land, or with more batteries could carry lighter loads longer distances to pick up supplies in town. There are some cute Renault delivery vans available in France for around $7000 that would be ideal for bringing produce to the local farmer's market, although I'm not sure if legal to import into this country (www.evalbum.com).
Randy Holmquist puts together very nice commercial electric trucks up in British Columbia. The "Might-E Truck" and the Izuzu NPR can be custom configured and are generally designed for larger payload capacity and speeds under 25 mph (Canadian Electric Vehicles Ltd., 250-954-2230, www.canev.com).
Rechargeable batteries are the only practical way to store electricity and carry it around with you. Fuel cells have received a lot of press recently, but are still decades away, as are portable flywheels and other experimental concepts.
The common lead-acid battery, found under the hood of every car, has been around for over 100 years. As a result, plenty of recycling options are in place for disposing of old batteries. If trying to make an electric car with more than a 200 or 300 mile range, then exotic batteries are a must, but the tried and true lead-acid battery is great for electric tractor applications. The lead is of course heavy, but that just reduces the amount of dead weight that is added to the front of the tractor or in the wheels.
Lead acid batteries come in several varieties flooded, gelled, and AGM and can be tailored to different applications such as a car starter battery, marine use, and deep-cycle. The flooded deep-cycle versions, with caps you can remove and see the electrolyte inside, are the most practical choice for an electric tractor. Gel cells are sealed so there is no mess to deal with, but are more expensive and would not last long in a tractor. AGMs are also sealed and even more expensive, but would perform very well although with slightly less range. The up-front cost of the AGMs and the cost of the sophisticated charger required make them hard to justify.
Many other battery chemistries have been developed, but aren't likely to be used in an electric tractor. Some options, such as nickel-cadmium (NiCad) have been around for years. Companies like SAFT that make the larger flooded NiCads have an aggressive recycling program in place and an excellent environmental record. NiCads are solid performers, but the higher price for lighter weight is difficult to justify when weight isn't a problem.
Newer battery chemistries, such as Nickel Metal Hydroxide, Nickel Zinc, and Lithium Ion are common in small sizes for cell phones, laptop computers and other consumer electronics. Larger versions useful in electric vehicles are still very experimental and generally prohibitively expensive. Large size, relatively low cost, lithium ion and nickel zinc batteries made in China are just starting to appear on the market, but I have serious reservations about the manufacturing conditions and the reliability of these units.
Unfortunately the battery industry is loaded with products that claim to heal all that ails your battery. Liquids or powders that you add to the electrolyte do absolutely nothing. Little black boxes that pulse or resonate the battery are also of little use for most people, in my opinion. Regular AC power pulses 60 times per second and ordinary chargers pass these pulses on to the battery. However, these pulse devices may help those charging from pure DC, such as with an off-grid solar system.
In general, batteries are like people and respond well to a good diet, comfortable temperatures, and regular exercise. With flooded batteries, it is important to take off the caps every few weeks and add clean distilled water as needed. During the final phase of charging it is normal for the electrolyte to bubble and gas, but this boils off water that must be replenished before the plates get exposed.
Lead acid batteries are happiest around 80º F. At higher temperatures, they will perform better but have a shorter life and at colder temperatures the range will drop off - significantly when below 40º or 50º F. You can still use them in the winter, but expect to charge more often. The batteries should always be stored fully charged, and this is even more important in the New England winter as a discharged battery is prone to freezing and cracking.
If the batteries have gone unused for a while, expect them to seem a little sluggish at first. A few cycles of gentle exercise and charging will wake them right back up. With some basic care, the batteries in your tractor will provide years of service.
I may be biased, but I feel that electric tractors and other electric machines are a great match to smaller farms. For a larger operation, you might consider biodiesel for the big equipment and electric for the smaller equipment. If you are interested, check out the resources listed, find me on the web, and I'll be happy to tell you more (www.eeevee.com).
With thanks to the members of the Elec-Trak and Electric Vehicle Discussion Lists and the NOFA/Mass folks who have talked to me at the summer conferences and at farmer's markets for all the great information and ideas!
Note: This article was originally written for and pulished in the Spring 2003 issue of The Natural Farmer, the newspaper of the Northeast Organic Farming Association. Copyright 2003, The Natural Farmer. Reprinted by permission.
|Jim's E-Home||December 20, 2003|