Organically Electric Farmer
By Bill Moore
The sun plays a pivotal role in all agriculture. Plants use its invisible photons to convert carbon dioxide and water into carbohydrates. The by-product is oxygen, as well as energy. It's a miraculous process that sustains virtually all life on the planet.
Now the sun is also powering a pair of tractors on a small organic farm in New Paltz, New York, an hour and a half drive up the Hudson Valley from New York City.
Huguenot Street Farm consists of 77 acres of forest, pasture and tillable land. Some 25 acres of it is used to organically grow 40 different types of fruits and vegetables that are shared with 225 families who "subscribe" each year in the farm's Community Supported Agriculture or CSA program, paying from $325 to $650 annually depending on the amount of produce they want. Ron Khosla and his wife plant 13 arces in vegetables each year, rotating fields regularly to maintain their fertility.
To help them cultivate, plant and weed the fields, they own two fifty-year old Allis Chalmer G model tractors, both of which have been converted to electric drive. We heard about Khosla's ground-breaking conversion and arranged to talk to him about it. Technical problems forced us to edit out the first few minutes of our conversation, but the key parts about why and how he converted the gasoline-burning tractors to solar-electric power came through just fine on the accompanying MP3 audio file.
The Khoslas, neither of whom had a background in farming -- Ron had worked in computers previously -- invested their life savings in the farm, picking up their first G model for $1000. It had been as well maintained as possible for a machine that was half-a-century old.
"I was always fiddling with the carburetor or getting the mixtures just right. The weather would change and in farming everything is so weather-dependent. If you can do something on day one, it's a tenth of the work than if you do it on day five. So we needed a machine that we could hop on, do the work that we were doing, get off it and move on with our lives as quickly as possible.
"So the gasoline engine being fifty years old just wasn't fitting the bill".
Khosla discussed the problem with another farmer who'd pulled off the tired, old gasoline engine and replaced it with a newer diesel engine. He then heard about one that ran on biodiesel in Massachusetts
Instead of pursuing the internal combustion engine route, he figured that since this was a tractor that moved slowly over relatively short distances, why not convert it to run on an electric motor? Surely, it had to be cheaper and simpler.
"Tractors are uniquely qualified for being electrified. In a car you've got to go forty miles a day. I don't think I do 40 miles in a season. I just need something that will carry me the two miles that I am going to go in a given day driving back and forth at very low speeds to do the work I need to do. And, ironically, the batteries… you can position right over the wheels to give you a little extra traction".
Khosla admits that he had almost no knowledge of how to convert the tractor to electric. He'd never seen an electric bicycle, much less an electric car. But he knew enough about electric motors to know that their torque profile was ideally suited for driving a farm tractor. Whereas IC engine tractors can only develop their maximum torque at high RPM settings, the electric motor provides it as soon as it turns on.
"Just from a straight common sense perspective, the electric motor is a more efficient way of transferring power at low speeds," he explained. "The more you think about it, why aren't all tractors electric?"
Khosla's G model tractor. Batteries are visible just behind the driver. More photos of the conversion are available the farm's web site.
Khosla turned to Bob Batson at EV America for advice, as well as for his motor and controller.
One of the first challenges was reducing the speed of the electric motor to more closely match the speed of gasoline engine it was replacing. The first solution was to jury-rig a pulley system fabricated from old combine parts scrounged from a neighbor's junk pile. Despite its appearance it worked flawlessly for two years until Khosla replaced it with a better engineered unit using a motorcycle timing gear.
Both tractors are 48-volt, one using four 12-volt batteries and the other using six 8-volt batteries. Both are charged from a pair of solar panels that are moved into the field each season on loading pallets. He has since discovered that he didn't need to have so much power, explaining that he once ran the first tractor for three weeks without recharging, but it was a costly lesson. He ruined his first set of batteries, learning that he needs to keep them charged; hence the idea of using the solar panels.
While seeding uses very little power, cultivating and weeding places high demands on the battery, but since Khosla only works up to a acre a day, he has plenty of a 'juice' to do the job. He added that should he have to do two acres, he can let the tractor recharge over the lunch hour.
The learning curve for doing the first tractor conversion took about five weeks of tinkering and fiddling. The second tractor required only two weeks. Since then, he's done three over conversions, which can be accomplished in just a couple days. The machinist who machined the adapter plate and gear reducer has since sold three other kits, so the idea appears to be slowly catching on.
Khosla used a USDA SEAR grant to not only improve the design of the conversion but to also acquire solar photovoltaic panels that he planned to mount on top of the tractor to trickle charge the batteries while working in the field, as well as provide shade for the operator.
But he quickly discovered that wasn't a good idea. The panels were heavy and he was concerned about their durability after bouncing over rough fields all day. He was also concerned about wind getting under them and causing potential tip-over problems.
Instead, he mounted them on conventional shipping pallets that can be moved using a tractor he owns that has a forklift attachment on it. He places the panels along the edge of the fields to be worked and when he's done with the 'G' model, he plugs it in to recharge it.
In retrospect, he acknowledged that it takes so little electric power to recharge his tractors that the solar panels probably won't pay for themselves, but they do offer a convenient, pollution-free way to run his farm machines.
Khosla concluded by saying that the reason he got into organic farming was for the challenge of doing something new and different every day.
To learn more about his 'G' model conversion, visit the "FlyingBeet.Com" web site. You'll find fairly detailed instructions on how to do the conversion. Please note that Ron and his wife are currently out of the country until after the first of the year, if you have questions wait until then before contact him. He said he'd be happy to correspond with anyone interested in what he's learned.