www.RENEWABLES.com Toward Sustainable Agriculture By Stephen Heckeroth

Most discussions about sustainable agriculture revolve around organic methods, precision cultivation or integrated pest management but there has so far been very little concern expressed about agriculture's petroleum dependence. Sustainability requires the maintenance of air, water and soil quality and the efficient and equitable use of resources . At the turn of the last century over half the people in this country lived sustainably on family farms. Now 100 years later, less than two percent of the population grows most of the food. The development of farm machinery and a distribution system powered by fossil fuel is largely responsible for this phenomenal gain in productivity. As we approach the peak of world oil production it is time to ask about the social and environmental cost associated with oil dependence and explore sustainable alternatives.      The finite nature of the petroleum resource is universally acknowledged, yet the fact that there is an end to the petroleum resource is universally ignored. Food production and distribution in the developed world has become so dependent on petroleum use, it's hard to imagine how agriculture will function without it. The latest records from the US Department of Agriculture state that US crop production consumed 1.4 billion gallons of gasoline, 3.5 billion gallons of diesel and .9 billion gallons of propane in 1994.      In the early '70s, US domestic oil extraction reached its peak. Instead of learning to live within our means, the US set its sights on controlling world oil "production". The current oil glut is the result of successful US corporate and military control of world oil extraction. The spiraling of excess supply, lower prices and increased consumption is shortening the time to peak world oil extraction, predicted by experts to happen in less than 20 years. Predicted Peak in World Oil Production Source Peak Date F. Bernabe, ENI SpA (1998) 2000-2005 C. Campbell and J. Laherrene, Petroconsultants (1998) 2000-2010 J. MacKenzie, World Resources Institute (1996) 2007-2014 OECD's International Energy Agency (1998) 2010-2020 DOE's Energy Information Administration (1998) before 2020      When the peak comes, a crisis similar to that suffered in the US in the '70s will be worldwide and last until an alternative to petroleum is found. Aside from oil depletion and the personal health risks from exhaust and noise, there are many other concerns raised by our dependence on fossil fuel: soil compaction; global climate change; loss of biodiversity; loss of traditional farming skills and indigenous food supplies; armed conflict and the return to a feudal system.

Soil Compaction

Soil in its natural condition is a sponge of living and decomposing organic matter. Compaction restricts the soil's ability to absorb water which limits ground water recharge and increases runoff. Runoff carries soil into streams and rivers which diminishes the quality of both land and water. A person walking compacts the soil at about 2 to 3 pounds per square inch (psi). A well designed tractor with floatation tires can exert even less pressure on the soil. However, a car or heavy tractor with an aggressive tread can exert more than 20 psi and turn healthy soil into pavement. Wet soils are more susceptible to compaction and production pressures often cause farmers to enter fields too soon after the rainy season. Refined petroleum products have given modern farmers the power to treat soil like a lifeless medium to be plowed, sterilized and chemically fertilized then plowed again. Conventional farming methods lead to a loss of soil quality and the erosion of 3 billion tons of topsoil in the U.S. each year.

Global Climate Change

Every gallon of fuel burned creates 20 pounds of carbon dioxide which has been implicated as a major factor in global climate change. The changes forecast by scientists will have a critical impact on agricultural production, especially in populated equatorial regions. Fourteen of the 20 warmest years in the last century have occurred since 1980 with '97 and '98 being the hottest years on record. Some agricultural regions have suffered crippling drought while an increased number and intensity of storms has caused flooding, high winds and erosion devastating agricultural areas worldwide.

Loss of Biodiversity

Armed with an arsenal of genetically engineered crops, herbicides, pesticides and fertilizers and ever bigger machinery farmers do battle with biodiversity. Increased production has been obtained at the expense of a diverse genetic pool. Over 75 percent of the genetic diversity of the world's food crops has been lost since the beginning of the century. Only 20 of the more than 7,000 plant species that have been used for food now provide 90 percent of what people eat. Wheat, corn and rice account for 50 percent. A diverse gene pool is nature's safeguard against extinction. It is also the repertoire that allows positive evolution. Each organism and its genes are the product of millions of years of adaptation and once they are lost they can never be recovered.

Loss of Traditional Farming Skills and Indigenous Food Supplies

Reliance on fossil fuel has reduced the manual labor necessary to grow food but labor intensive farming methods passed down for centuries even millennia have been lost. As monoculture agribusiness spreads to developing countries more traditional farming skills and indigenous food supplies will disappear. Those who formerly took pride in being able to feed themselves, their families and their communities are stripped of their land and livelihood and the joy and understanding that comes with participation in the cycle of life is lost.

Armed Conflict and the Return to Feudalism

Less than 20 percent of the world's population now exploits and controls the world's entire petroleum resource. Current trends suggest continued consolidation of power over the earth's remaining resources by a handful of global corporations. To make matters worse, the developed countries are currently pushing their oil dependent technologies on the rest of the world. If this continues agribusiness monoculture will have completely displaced traditional farming methods in developing countries at about the time the petroleum resource is depleted.      As the energy available from finite resources is exhausted competition over the last remaining supplies will turn into global conflict and the work now done by machines will be replaced with a feudal system or forced labor until an alternative is found.

Transition Fuels

Returning to an agrarian labor intensive economy is not a likely scenario for a burgeoning population that thinks food comes from the store. Draft animals have been successfully used for centuries to increase production. But it takes at least three acres of prime agricultural land and more than 10 acres of grassland to feed one workhorse. Biogas and waste vegetable oil are very important transition fuels capable of powering conventional agricultural equipment. However, the long-term pressure to convert agricultural land to biofuel production would result in a decrease in food crop land and the burning of biofuels still creates harmful emissions.      Fuel cells have also been suggested as an alternative. But fuels cells produce electricity and would require converting tractors to electric propulsion. The hydrogen used in fuel cells is either obtained by the electrolysis of water, which uses more energy than is available from the hydrogen produced, or is reformed from fossil fuel.      Electricity is a good transitional fuel because night time charging takes advantage of the utility's excess off-peak capacity and improves the overall performance of the grid. Electricity is also an ideal long-term sustainable fuel because it can be efficiently generated from renewable sources without causing pollution.

The Good News

More solar energy strikes the earth every day than the energy available from the world's entire petroleum resource. This means that there is a clean, virtually unlimited supply of energy from the sun which can be harnessed to satisfy most of our energy demands. Solar radiation has been used historically as a heat source or to dehydrate food for storage. Wind and rain are also the result of solar radiation and have been harnessed by people for thousands of years. Wind and falling water have been used as a power source for tasks like pumping water for irrigation or milling flour for bread. More recently wind has also been harnessed to generate power and in areas with high average wind speed wind generators are the least expensive means of producing electricity.      The energy available from water flowing down hill in intermittent streams that do not provide fish habitat is a largely untapped source of electricity. By collecting runoff and piping it downhill to a small electric turbine erosion can be avoided and electricity produced at the same time.      With the invention of photovoltaic (PV) panels solar energy can be converted directly into electricity. The PV panels currently on the market have proven efficiencies of converting over 10% of the solar energy available into electricity. This means that every square meter of photovoltaic panel exposed to sunlight is capable of producing 100 Watts of electricity. Photovoltaics are 30 times more efficient at converting solar energy into electricity than an electric plant powered by biofuels, and millions of times more efficient than fossil fuels. Wind generators and microhydro electric turbines are an ideal compliment to electricity produced by PV panels for providing power throughout the year.

Electric propulsion

Electric propulsion is the only high efficiency, zero emission technology now available to power agricultural equipment. Electric motors have only one moving part and require very little maintenance. Internal combustion engines, on the other hand, have hundreds of moving parts and require a lot of maintenance. Electric motors can operate at over 90% efficiency while combustion engines are less than 15% efficient. Electric propulsion is ideally suited to high torque, slow speed agricultural operations. Electric motors do not idle. Beyond that, an electric motor can be turned into a generator while going down hill or braking returning energy to the battery. This process, called regenerative braking, further increases the efficiency of electric propulsion and cannot be duplicated using any other fuel. The use of electric wheel motors eliminates the need for an internal combustion engine, transmission and differential which have always influenced the design of tractors. Mounting an electric motor in the hub creates a self-propelled wheel that offers a whole new level of versatility and visibility.

The Electric Tractor

Battery weight is the biggest obstacle to the performance of most electric vehicles. A tractor's performance depends on weight for traction, consequently heavy, deep-cycle, lead-acid batteries that are inexpensive, recyclable and long lived can be used to great advantage. In addition to an on-board battery pack between the traction wheels, auxiliary battery packs can be self-loaded on the tractor's three-point hitches to balance implement weight and extend operating time. Electric linear actuators are used to replace inefficient hydraulics for steering and for positioning the three-point hitches. The electric tractor has a separate power take off motor that can be sized for specific needs and operates independent of ground speed.      Even with the present oil glut and all time low fuel prices there are still applications for a non-polluting electric tractor powered from renewable sources. These applications include greenhouses and organic farms where air quality is a concern; golf courses surrounded by expensive homes where noise is a concern; planting and harvesting where very slow speeds are necessary; and remote control operation where safety is a concern; as well as multiple applications in developing countries that lack a fossil fuel infrastructure and have high fuel prices. The electric tractor can also replace petroleum powered generators as a mobile power source in remote areas and in emergency applications. Because the electric tractor is made from modular components, it can be assembled in any small shop and does not require a large energy intensive manufacturing facility. When the petroleum resource is finally depleted, the solar electric tractor could provide a way to maintain food production.

Multi position seat

The seat can be moved to four different positions on and off the tractor which will allow a multitude of operations that could only be accomplished by several conventional machines. This is possible because all the controls are conveniently mounted on the arm rests and only connected by small flexible wires or radio control transmitters. Forward high position - The high forward seat position is the same as on conventional tractors but allows unobstructed visibility for operations like precision cultivation. Reverse seat position - With the seat placed in the reverse position the solar electric tractor can replace several other conventional machines. Commercial loaders and forklifts are designed to put weight on the traction wheels and take weight off the steering wheels for optimum performance. High end commercial mowers are configured to put the implement out front for visibility and maneuverability. The operation of other implements like post hole diggers and backhoes can also benefit from the reverse seat operation. The open space toward the front of the tractor is also an ideal place to mount a dumpbed. Solar electric tractor with seat in rear facing position featuring improved implement visibility and auxiliary battery pack mounted on mid three-point hitch. Planting and Harvesting - The seat can be mounted on the mid or rear three-point-hitch and raised or lowered for planting and harvesting operations. Hundreds of pounds of seedlings or harvested crop can be stored easily on accessible trays and the other available three-point-hitch can be used at the same time to carry a water tank, cultivator, or bed preparation implement. Off tractor position - The relative ease of operating an electric vehicle by remote or computer control allows the seat to be removed from the tractor. This makes the electric tractor ideally suited for repetitive agricultural operations, bomb disposal, mine sweep, toxic cleanup and some road maintenance applications.

Photovoltaic Charging

If an electric tractor is combined with photovoltaic charging, either on the tractor itself in the form of a shade canopy or on the roof of a building, no other refueling infrastructure is necessary. Unbreakable photovoltaic panels and photovoltaic roofing with a 20 year warranty are now available that can turn any surface exposed to the sun into a power station. Photovoltaics provide an ideal energy source for agriculture because the growing season coincides with the availability of solar energy.

Conclusion

Agriculture as practiced in the developed world today is far from sustainable. Eighty years of petroleum dependence has degraded the earth's life support system to the point where maintaining air, water and soil quality is no longer enough. Humanity's survival depends on regaining the environmental quality in which we evolved. The only source of energy capable of replacing fossil fuels is the source that made them. The petroleum resource may last another 50 years, the sun won't burn out for 5.5 billion years. Which resource do you think we should use? Solar electric tractor with seat mounted in planter/harvester position with photovoltaic shade canopy tilted toward the sun and 3 kW photovoltaic barn roof in the background. That's Stephen in the saddle.

	Stephen Heckeroth www.RENEWABLES.com 30151 Navarro Ridge Albion, CA 95410 phone/FAX 707-937-0338
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