Electric Vehicles Powered By Friction: A Feasibility Study

By RAPHAEL MORALLO, Muntinlupa City, The Philippines

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In a constantly changing and progressive world where the supply of non-renewable resources such as fossil fuels is at high risk, proper action must be taken for the transportation industry to compensate for such a phenomenon. however the reliance on the hybrid-electric and full-electric automobile model still poses a large carbon footprint. One alternative is to utilize the rotatory movement of the wheels of an automobile to produce enough triboelectric energy to eventually power a vehicle. This research develops and constructs one possible prototype model for such a system and derives its possible current output when used alongside existing 120V and 240V electric car batteries. Although the design succeeds conceptually as a power source, its theoretical outputs will be unable to power an electric vehicle safely. Nevertheless, this research aims to initiate further studies on triboelectric power generation for commercial applications.

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Introduction
 
The development of hybrid-electric automobiles is a significant step in the movement of the automobile industry towards cleaner and more sustainable products as a response to its high consumption of gasoline, petroleum, and diesel. However, in the search for the ideal solution, present automobiles that brand itself as hybrid-electric or fully-electric still create a large carbon footprint - the amount of harmful carbon compounds it expends - since the generation of electricity typically involves fossil fuels similar to those used in automobiles that run on gasoline, petroleum, or diesel. These fossil fuels generally produce carbon compounds, primarily carbon dioxide, that are expelled into the atmosphere which create a greenhouse effect wherein the gases trap heat from the sun inside the earth. This phenomenon is what is fueling the acceleration of climate change and global warming, and without the proper action towards this problem, the planet could face surmounting problems.
 
In response to this need for automobiles that create a small carbon footprint, there needs to be development on automobiles that are independent on fossil fuels as completely as possible. The development of these kinds of automobiles that distance itself from non-renewable energy is essential not only to the development of the industry but also the movement towards a more sustainable environment. This paper explains how this development comes in the form of an electric system reliant on the friction that can be collected by the rotary movement of the wheels of an automobiles in order to power a battery that runs the automobile.
 
Essential to this study is the concept of how the interaction between two objects creates heat as a result of the friction between them and how this heat can be converted to electricity. Friction is the force that is exerted between two objects in contact with one another or the force that is required to move an object that is in placed on another. The interaction between these two objects can either be sliding or rolling, depending on how the two objects are in contact. Due to the fundamental principles of triboelectric effect,
or the study of the correlation between friction and electricity, the frictional interaction between two objects can cause charge separations in ionic materials that can set up large electrostatic potentials which can be discharged in the surroundings of the two objects. This is because of the presence of frictional heat which is capable of exciting the electrons of ionic materials to create an electric charge, thus presenting the relationship between heat and electricity wherein the amount of frictional heat determines the amount of electrons that can be discharged, being chemical change. In other words, the kinetic friction between two objects can create electric discharges, and the amount of discharge is dependent of the amount of kinetic friction exerted. This concept can be translated into the mechanism of automobiles. Therefore, by taking advantage of the rotary movement of the wheels of an automobile, friction can be generated within the car that can be converted into electricity enough to power a hybrid-electric automobile.
 
Similar mechanisms have already been invented pertaining to the collection of electricity from friction generated by the movement of an object. One of the pioneer systems, an early version of an electrical machine, relies on the high rate of rotation of a glass disc pressed by rubbers to create friction, and a set of brass balls and rods collect the electricity it generates. This is due to the conductive nature of the material to electricity that allows electric charges to polarize the material and transmit the discharged electrons. At the same time, the friction exerted by the system is greatly dependent on the amount of rotation the disc experiences, and because of triboelectricity, the amount of electricity discharged by the system is dependent on the amount of rotation experienced by the disc. A more recent and intricate application of this design has been done by students of the Georgia Institute of Technology who have designed a touchscreen powered by everyday movements such as walking and running. The touchscreen contains a polymer layer and a polydimethylsiloxane layer, two dissimilar surfaces where the former gives off electrons while the latter accepts electrons. While a device with this screen is in one’s pocket, the movement of the phone inside the pocket as the person walks or runs allows the two layers to rub against each other. This creates an alternating current that eventually self-powers the screen. Because of the structure of an automobile, its wheels constantly move whenever the automobile is in motion, and it follows that these wheels create the most rotational movement in an automobile. By utilizing this innate rotary movement, the car will essentially self-power itself for majority of the time it is used on the road.
 
The subsequent experiment design is believed to be most applicable in an actual automobile prototype because the mechanism of the experiment can be easily integrated into a realistic automobile design, which is to be attached to the wheels of a car. The experiment in general would prove that such mechanism can easily be put into automobiles to develop more sustainable designs, and it would open up further studies on alternative energy sources for transportation. Therefore, it is valuable that in the development of more efficient automobiles, the potential energy of the rotational movement of the wheels must be considered in the creation of new energy sources for automobiles to secure the sustainability of the industry.
 
Methodology
 
The experiment seeks to test the potential of a modified electrical machine to produce the right amount of electricity to power an electric of electric-hybrid vehicle in the most efficient way possible. The design of the mechanism will be patterned after early prototypes of simple electrical machines involving pressing and rapidly spinning a disc made of a material that gives off electrons onto another material that accepts electrons. A similar method has previously been done by students of the Georgia Institute of Technology by utilizing the movement of a smartphone in a person’s pocket to create friction between two layers of dissimilar material to produce an alternating current that eventually self-powers the screen. Applied to an actual vehicle, the spinning disc will be attached to the inside of its wheels while the second material will be a component found inside the car connected to the vehicle’s battery in order to create the needed current.
 
For this experiment, the two materials that will be used are Polyvinyl and Aluminium, wherein a disc with a Polyvinyl surface and with a radius of 9 cm will be pressed and spun on top of an square Aluminium surface with side length 20 cm. In order to create an efficient flow of electricity that can be harnessed, the polyvinyl surface must contain small perforations or scores to allow space in the middle of the two materials for the electricity to flow. The spinning movement of the polyvinyl disc will be applied by a hand drill running at 1,200 revolutions per minute, simulating a linear velocity of 40.71 kilometers per hour. The generated electricity will then be captured by copper wires attached to the Aluminium surface, and the wires will be connected to a multi-tester to observe the amount of current the mechanism produces.
 
The execution of the experiment will be done as follows: First, the polyvinyl disc must first be attached to the end of a drill while the Aluminium surface is laid down on a flat surface with additional components to keep it still during the experiment. Second, wires will be attached to the Aluminium and the multi-tester. Third, the polyvinyl disc will be placed on top of the Aluminium, and for one minute, the drill will be turned on. While the disc is spinning, the maximum and minimum readings of current from the multi-tester will be recorded. Simple analysis of the values will follow, and an evaluation of the design will be made. The efficiency and potential of the design for use in practical applications will rely on whether or not the output values of current will match the industry requirement for the operation of current models of electric and hybrid cars. This means that the design must be able to produce a current of 83.33 ampere in on hour to operate a 120-volt battery or a current of 41.66 amperes in one hour to operate a 240-volt battery, both producing 10 kilowatt-hours.
 
Provided that the design meets the standards required by current battery specifications, the design would be a practical source of alternative energy because first, it creates a self-powering mechanism that allows cars to minimize its use of fuel during use. Second, the method requires inexpensive materials to operate, and it can easily integrate into a variety of automobiles. This also means that the design will be able to be in use even in older versions of electric or electric-hybrid vehicles. Lastly, the procedure of the experiment is an accurate representation of its expected performance in a standard vehicle, and the simplicity of the design allows it to require low maintenance while in operation. In other words, the design should be capable of operating over long periods of time, and it should have no problem in implementing itself into existing vehicles.
 
Results
 
The experiment was tested out theoretically using the mathematical interpretations of friction, particularly between Aluminium and polyvinyl, and applying principles of mechanics to determine the ampere-hour output of the mechanism. The following equations detail the solution in obtaining the theoretical output of the experimental design.
 
The first value to be considered is the frictional force that exists between the Aluminium and polyvinyl surfaces, illustrated by equation (1) where f is the frictional force in Newtons, m is the coefficient of friction, and N is the force exerted between the surfaces in Newtons.
 
f = mN
(1)

The first element of equation (1), the coefficient of friction, is the value which describes the ratio of the force of friction between two bodies and the force exerted towards each other. The values below were obtained from a set of common coefficient of friction between common materials. They represent the range of which that the coefficient of friction between Aluminium and polyvinyl varies.
 
m = [0.2; 0.3]
(2)

The second element of equation (1) is the normal force, the force exerted upon an object that is in contact with a stable object. This is illustrated by equation (3), with N as the normal force in Newtons, m as the mass of the object exerting the normal force in kilograms, and g representing gravity.
 
N = mg
(3)

m was set at 6 kilograms, 5 kilograms from the hand drill used and 1 kilogram as the mass of the vinyl plus the supporting structure that will hold it into the hand drill. Using 9.8 m=s2 (s, squared) as the acceleration due to gravity, the following value was obtained as the normal force.
 
N = 6kg = 58.5N
(4)

In order to maximize the range of the coefficient of friction of Aluminium and polyvinyl, the higher and lower bounds of the range were used in computing the frictional force. Thus, this gives a range of values for the frictional force as well, as illustrated below, where f1 represents the minimum value while f2 represents the maximum value.
 
f1 = 0.2(58.5N) = 11:76N
(5)

f2 = 0:3(58.5N) = 17:64N
(6)

Because the experiment aims to convert kinetic energy to electrical energy, a common unit must be used in order to mathematically translate between those two energies, and the most effective unit to use is power. Equation (7) has been utilized to obtain the mechanical power of the experimental design where F is the force, which in this case, is frictional force in Newtons, and v is the velocity of the force exerted in meters per second.
 
P = Fv
(7)
 
In this case, the frictional force is moved at the same velocity of a moving vehicle, which is, on average, 40.71 km=h. This converts to 11.308m =s. The following values were obtained from using the formula, where P1 is the minimum value and P2 is the maximum value.
 
P1 = 11.76N = 132:982W
(8)

P2 = 17.64N = 199:473W
(9)

Because the kinetic energy produced by the system can be converted to electrical energy, the kinetic power produced by the system can be converted to electrical power. Equation (10) is the fundamental formula for power, where P is power in Watts, I is current in Amperes, and V is the voltage of the system in Volts.
 
P = IV
(10)

Current car batteries are offered in two variants: one that operates with 120 V and another with 240 V. This means that P1 and P2 must be plugged in twice into the equation: once where V = 120 and another when V = 240. By manipulating the formula as a function of power,
 
f (P) = P/V = I
(11)

the values obtained previously for power can be used to identify the current of the system in amperes. The following values below were obtained using the formula for power as a function of power. I1 represents the current produced by the minimum value of power while I2 represents the current produced by the maximum value of power.
 
I1 = 1.108A; 0.554A
(12)
 
I2 = 1.662A; 0.831A
(13)

Since the calculations output the current produced in meters per second, these values must be converted to find the total current producing in Ampere-Hours (Ah). I3 is the conversion from I1 while I4 is the conversion from I2.
 
I3 = 3988.8Ah; 1994.4Ah
(14)
 
I4 = 5983.2Ah; 2991.6Ah
(15)
 
Therefore, the current output of the experimental mechanism ranges from 1999.4 Ah to 5983.2 Ah, depending on the voltage of the battery used and the actual coefficient of friction of the system.
 
Discussion
 
The results were expected in the context that consideration was not made for the high number of revolutions per minute of a moving car. It must be understood that the revolutions per minute more accurately determines the amount of frictional force and eventually the current output of the system rather than the speed of the car. At the same time, the results reflected the simplistic design of the system, which has gone against the safety and reliability of the mechanism. Additionally, because of the use of mathematics in the experiment, there could be unforeseen errors caused in the calculations which may have altered the results unknowingly. Ultimately, the results were inconsistent with the preconceived idea that a simple mechanism would make the solution easier.
 
Current car battery models require around 83.33 ampere-hours for the 120-V variant and around 41.66 ampere-hours for the 240-V variant. Clearly, the experimental design greatly exceeds those standards, and at the same time, these calculations imply a great amount of energy that is being transferred through the system, thus causing major damage to the system. For example, the high and varied velocity may cause the copper wires to disconnect from the system, or the small axle that connects the hand drill to the vinyl surface may wear out. Possible outcomes when this design is used on actual batteries may include overcharging of the battery and overheating of the system, which will destroy the battery itself. Both can result in significant damage not only to the friction-powered system but also surrounding component of the vehicle that may be affected by the intense heat output of the mechanism.
 
However, the concept of the design should not be ruled out. Several design improvements can be made simply by observing the output of the experimental design. First, in order to decrease the current output to a desirable level, the rotating parts of the system must contain gears in order to produce rotation that is slower than that of the wheels of a moving car. Second, in order to collect more electricity and reduce the wearing of the copper wires, the Aluminium plate must be dotted with the ends of industry-standard electrical wiring instead of having simple wires put directly on the Aluminium plate. Those wires will connect to the battery in order to charge it. Third, as a precautionary measure, fuses and other safety devices must be in place in order to prevent damage to the system when it is over its capacity. Fourth, the experiment never saw a physical simulation due to the lack of resources needed to recreate the design and is therefore open to changes. Using these suggestions along with the data presented in this study, a physical design can still be made and further study must be done upon it.
 
As a relatively new technology, this must be further studied in order to make it available for commercial automobile manufacturers. This study only opens the possibility of a fuel-independent power system, which is a leap forward into environmentally-friendly transport. At the same time, this study hopes to be taken into consideration by the rest of scientific community in order to fuel develop more efficient modes of transport. Putting the study into the context of improving transportation in general, the results of the study aims to initiate research on cheaper land transport by creating drastic cost-cutting improvements in the vehicle itself.
 
In conclusion, the results have determined the experimental design nonconforming to standards but certainly proves that such a system can be used in the future.

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