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.