Sustainable farm power through use of hybrid power systems on tractors

Emissions resulting from farm power

Unlike many other challenges the mankind faces in the process of advancing its life on this Earth, climate change is too complex a problem first to understand and then to find solutions. Every country - rich or poor, developed or developing – strives to protect, enable and nurture its farming community with appropriate policy interventions and economic incentives. But, the very same nation state is hard lined about anything that compromises its environment, ecology and eco – systems. These essential elements are non – negotiable in the eyes of every nation state owing to their indispensable nature in creation, sustenance and evolution of life forms on Earth. While the demand for power on the farm has been on the rise globally as more and more farmers shift towards mechanized farming, there is a corresponding rise in the quantum of emissions resulting from the use of fossil fuels for powering agricultural tractors. The alarm bells are ringing louder and clear for everyone to pull the socks and gear up for the ever stricter emissions regulation. Therefore, it is imperative to develop, transfer and adopt greener technologies that leave a smaller carbon foot – print and helps to promote sustainable agriculture.

Hybrid power systems

Utilizing the synergy arising out of combining power systems having distinct characteristics, the engineering community is attempting to redefine and change the landscape of mobility solutions forever. In automotive parlance this synergistic combination is called a hybrid. Attempts were underway for over a century now to build and use hybrid power systems with the earliest attempt dating back to circa 1899. The earliest known hybrid was an electro – muscular hybrid which uses an electro motive force in combination with human muscular power. In pursuit of finding new and efficient solutions, several innovative hybrid combinations emerged with passing of time. The most widely known hybrid being the petro – electric hybrid which uses a petrol powered internal combustion engine in combination with electrical batteries for mobilizing the vehicle. Other well known hybrids include petro – hydraulic, petro – pneumatic and chemo – electric hybrids. The chemo – electric hybrid is a combinatorial use of fuel cells with electrical batteries for propelling a vehicle. Several automotive manufacturers across the world have successfully built hybrid passenger vehicles and the most iconic among them being the Prius from Toyota. Although the technical know – how on hybrids has evolved significantly over time, there was no convergence which in effect prevented the migration of hybrid related technical know – how from passenger vehicles to be used in off – highway vehicles. Besides, the power demand characteristics of a tractor are significantly different to that of a passenger vehicle which calls for newer solutions.

Agricultural tractor and its power characteristics 

An agricultural tractor is a versatile machine and an important source of power on the farm. Although tractor per se has limited utility on the farm, the versatility of this machine lies in its ability to carry and operate a wide range of farm equipments in order to perform various agricultural operations which includes but not limited to soil manipulation, seed drilling, crop care, crop harvesting and grain transport. Performing any of these operations on the farm requires a source of power which in one form is an agricultural tractor of a specific power rating. Selecting a tractor of a particular power rating is a function of the kind of agricultural operation to be performed, specifications of the farm equipments to be used for performing a given agricultural operation, size of the land holding, soil conditions and desired operational time for performing a given operation. For a given power rating, the one factor which distinguishes a tractor from a passenger car is the torque generated in the final drive. Tractors are high torque machines and this particular characteristic is advantageously used for leveraging tractor as a source of power on the farm. Also, in contrast to a passenger car, the power output of a tractor must have to remain high and constant for a prolonged period of time in the course of performing a given agricultural operation.

Tractors with hybrid power systems

Tractors with hybrid power systems as a concept is gaining momentum in the last couple of decades. As a conventional approach, the engines are down sized or down rated and the corresponding balance in power is supplemented by a suitable electrical means either in the form of a battery or an electrical motor operationally coupled to each other. The fundamental advantage underlying a hybrid machine is the minimal transfer losses involved when the power is transferred over wires or cables as against the transfer of power by means of mechanical drives. A multi – faceted approach is taken to explore and deduce hybrid solutions keeping in mind the need to generate and maintain constant power for a prolonged time interval. One of the most widely accepted hybrid solutions is the use of hydraulic power in combination with motive power of the engine. Yet another known hybrid technology involves switching the type of input fuel for the engine depending upon the external load requirements. The major players in the global tractor market have started taking patent positions in the field of hybrid tractors. A shift from a conventional engine based power system to a hybrid power system in a high torque machine like a tractor calls for significant changes in power generation, regeneration, transfer and use and many of these technically novel changes are patent protected. For example, Case New Holland (CNH) claims an arrangement of at least two electrical machines in a structural casing defining a transmission which is operationally coupled to an internal combustion engine of a hybrid power train in its patent EP1317050 B1. Another important technology from AGCO which is worth noting in the field of hybrid tractors is known through the patent publication US20130047753 A1 which claims the partial or full operation of the power take off by electrical energy from battery.

Need for sustainable farm power

Tractor will continue to remain an indispensable machine on the farm. With the increased relevancy of farm tractor in modern agriculture there is a corresponding increase in its use and adoption which has a direct bearing on the emission of noxious gases. There is an immediacy of purpose for appropriate technological interventions to check the growing menace of on the farm emissions. Agriculture being existential in nature for the mankind to survive and prosper, it is essential to adopt sustainable farming solutions which will create reliable and stable bio – systems for the generations to come. As they say, there is no culture without agriculture and one right step in this direction to create a sustainable foundation for agriculture is the development and adoption of environmental friendly technologies like hybrid power systems in tractors.

Precision Agriculture

Global Food Security status

Social scientists believe that the civilization on earth is as old as five thousand to seven thousand years. Since the dawn of civilization, human societies are inextricably linked to the soil, water, plant and animal biosystems. Human beings relied on these natural forms for their subsistence and survival and will continue to rely on them in the ages to come. Therefore, this interactive dependence on various biosystems has become inevitable for human existence. So, the necessity to safeguard these vital elements of nature is of paramount importance to the very sustenance of human race on earth. Today, the world population has crossed the mark of 6.6 billion and the annual rate of growth of population is estimated to be about 1.25 to 1.5%. That means a total of 80 million people are getting added to this planet every year. The global population is likely to get stabilized at 12 billion towards the end of this century. Despite the fact that the annual food grain production standing at 2100 Mt which translates to a global per capita production of 318 kg per year, 800 million people world wide continue to suffer from chronic hunger and malnutrition (FAO 2008 Report). Therefore, countries have the necessity to feed the growing millions of mouths. The United Nations continues to feed these third world countries whose standards of living are unimaginably impoverished. Augmenting food production will bring these millions of people under the food security net.

Agricultural and Environmental issues

Countries are under tremendous pressure to meet the growing demand for food and also the increasing threat to the environment due to unsustainable practices adopted in meeting these requirements. Increasing the food production seems to be a viable option to help achieve global food security. But, there are other issues which are associated with food production like falling productivity levels, resource constraints and increased use of chemical fertilizers. A recent survey points to the fact that 40% of the deaths in the world are caused due to environmental pollution. Damage caused to the environment due to the indiscriminate use of fertilizers and other chemicals is irreversible. Excessive use of macro fertilizers like N and P in agriculture leads to environmental degradation resulting in poor soil health and ground water contamination. Nitrogen is a potential source for ground water pollution. Due to its negative charge, nitrate ion does not get attracted to the soil particles and hence leeches along the soil profile in to the ground water. Blue baby syndrome, cancer and miscarriage are the common effects of consuming nitrate contaminated water. Similarly phosphorous impact on environment is through a process called eutrophication (accelerated growth of algae & duckweed leading to the increasing BOD value – more than 250 mg/L - of the water body there by inhibiting aquatic life forms). Human health concerns arising out of excess phosphorus are liver and kidney damage, skin burns, nausea and even fatality (white phosphorous). The world today is at cross roads, not knowing what direction to take in order to manage the myriad problems arising out of the Food vs. Environment dilemma.

Need for Precision Agriculture systems

Though organic farming methods can contain the environmental issues and assure high quality produce, it will be too early to shift the input base from chemical to organic. Progressive introduction of organic fertilizers will help in adjusting the farming systems to meet the demand for food. For now, organic fertilizers can only complement the use of chemical fertilizers. Therefore, the best strategy will be to rationalize the application of chemical fertilizers. Precision farming system is a robust method to help the farmers rationalize the application of inputs like fertilizers. Precision agriculture or precision farming is a modern agricultural concept relying on the existence of in – field variability. It is about doing the right thing, in the right place, in the right way and at the right time.

Elements of Precision Agriculture systems

Precision agriculture aims at integrating agriculture, information and machine systems at macro level. This is achieved through the use of elements like spatial referencing using GIS, soil, crop and climate monitoring, attribute mapping, decision support systems and differential action using GPS. GIS is a static mapping system. Where as GPS is a real time guiding system. Using spatial referencing, the farm plot is mapped and divided in to grids called micro-sites. GPS guided Grid sampling is done to understand the variability with in the crop, soil and climatic conditions. The data obtained in this will be used for attribute mapping. The attribute mapping will provide information relating to soil moisture and variable distribution of N-P-K across the field. The attribute mapping will be fed in to the Decision Support System which will generate an optimized model showing the variability of attributes across the field and subsequent commands to decrease the variability. This set of data commands will be supplied to the embedded systems of the farm equipment which will ultimately act in a differential pattern there by reducing the attribute variability. Precision agriculture is soon gaining popularity among the farming community. Many agriculture based technology companies are in to the business of making appropriate decision support tools and other equipment required for carrying precision agriculture.

Challenges

As far as precision agriculture goes, the road ahead is filled with challenges not only in its use but also its adaptability at farm level. Precision farming offers multitude of opportunities and equal number of limitations too. Better agronomic management can be achieved, only if the topography is favorable. Because of its technical advancement, time can be effectively managed. However, the systems are very complex for a layman to work upon without proper training and experience. Impact of agriculture on environment can be reduced through optimized nutrient management. But, precision agriculture is one of the many tools used in the process of making agriculture more sustainable. It is not an end in itself but only a means to a right end. Adoption of precision agriculture technologies is an excellent farm management strategy as it offers promising economical benefits like reduction in input cost and increase in efficiency. Again, the initial capital investment to procure all the required equipment & gadgets is somewhat high.