Piezoelectric Road Harvests Traffic Energy to Generate Electricity

(Sabir Hussain Shah, Islamabad)

At present, electricity has become a lifeline for human population. Its demand is increasing day by day. Modern technology needs a huge amount of electrical power for its various operations. Electricity production is the single largest source of pollution in the whole world. All the methods of producing electricity have certain drawbacks.

The burning of fossil fuels is the most widely used method of generating electricity. However, this method has the major drawback of severe environmental impact through air pollutant emission. Hydroelectric electricity generation eliminates the need to burn fuel, but it also creates a significant environmental impact on the water supply that drives the power generation equipment.

Therefore there is no end of the different ways; one can generate pollution-free electricity. At one hand, rising concern about the gap between demand and supply of electricity for masses has highlighted the exploration of alternate sources of energy and its (energy) sustainable use. On the other hand, traffic on road all over the world is increasing day by day and thus, congestion on roads is becoming inevitable with the fancy of masses towards personal transportation systems for their growing mobility.

Accordingly, it is an object of the present invention to provide a method of electrical power generation that does not negatively impact the environment.

The concept is not new, the application is a novelty. The first demonstration of the piezoelectric effect was given in 1880 by the brothers Pierre Curie and Jacques Curie using crystals of tourmaline, quartz, topaz, cane sugar, and Rochelle salt (sodium potassium tartrate tetrahydrate).

Piezoelectricity refers to the ability of some materials - most notably crystals and certain ceramics, including bone - to generate an electric potential in response to applied pressure. The word is derived from the Greek piezo or piezein, which means to squeeze or press. "The name of the game is harvesting," "Harvesting means energy which is available but is going to waste.”

Suitable Method of producing Electric Power:

The present invention relates generally to methods of electrical power generation, and more particularly is a method and device to generate electricity by using traffic on existing roadways to drive an electrical generator. Energy demand and heavy traffic correlation motivate to dream about a device in the road that would harvest the energy from the vehicles driving over it. For this, embed piezoelectric material beneath a road can provide the magic of converting pressure exerted by the moving vehicles into electric current. The method uses an electrical generation device installed beneath the roadbed. The electrical generation device includes a pressure plate covered with one or more protection layers which lie beneath the surface of the road.

When a vehicle passes over the electrical generation device, the pressure plate is pushed downward by the weight of the vehicle. The downward displacement of the pressure plate is used to drive an electrical generator. The electricity generated is then transmitted to a power grid, or collected and stored until it is used for specific public infrastructure purposes such as lighting and widespread use of the system would enable far greater scrutiny and hence understanding of the behaviour of road vehicles. The infrastructure captures and stores energy for reuse.

The piezoelectric effect converts mechanical strain into electrical current or voltage and the system is expected to scale up to 400 kilowatts from a 1-kilometre stretch of dual carriageway. The generators are embedded between the superstructure layers, and usually covered with an asphalt layer.

Piezoelectricity is used in the production and detection of sound, generation of high voltages, electronic frequency generation and everyday uses such as cigarette lighters and push-start propane barbecues. The system is based on piezoelectricity, which uses pads of metallic crystals buried over hundreds of meters of road to generate electricity when put under the pressure of quickly moving traffic. According to Abramovich, one truck can generate 2,000 volts which could already be used to power traffic lights or street lamps.

The generators are mounted with electronic cards supplying the storage system. The laying of the present system, (embedding the generators and electronic cards in to the roadway), can be done during paving of new roads or in the course of the maintenance work in existing roadways, so it’s entirely retrofittable to any road, and the heavier the vehicle, and the greater the number of vehicles, the greater the return, all the way to electricity production on an industrial scale.
Designs to Produce Piezoelectricity:

With this technology, now, engineers are poised to harvest some of the spare kinetic energy of the world’s moving vehicles with various designs being put forward. Mainly there are two designs of producing piezoelectricity:

First Design: It consists of a thin box around the piezoelectric material, which is then placed underneath a layer of asphalt. As trucks pass over plates embedded in the asphalt they compress a tank of hydraulic fluid under the road, which in turn creates a series of pumping actions that turns a generator to produce electricity. When a car drives over the box, it takes the vertical force and compresses the piezoelectric material, thereby generating electricity. The energy-80 kilowatt-hours per kilometer of road for car traffic can be stored in a nearby battery or super capacitor, depending on the application, or sent directly to streetlights and other roadside devices. The energy being converted into electricity through piezoelectric effect is coming from motion of vehicle which will otherwise be wasted by heat when the road deforms under the weight of the car. The layer of piezoelectric material is stiffer than the road material it replaces, so it even saves a tiny amount of energy.

Second design: It aims to capture energy when vehicles are slowing down in which cars or trucks would drive over a mat that would be installed on top of the road, on a highway off-ramp, or near a toll booth, saving wear and tear on the car brakes and transforming some of the slowing vehicle’s motion into electricity. The mat uses mechanical or hydraulic cells to generate electricity and can be customized for cars or cargo truck traffic.

These latest refinements maximize the amount of electricity generated without disrupting the driver or vehicle or robbing a vehicle of the energy it needs to accelerate. This is because the system is designed to be installed in locations where vehicles are required to reduce speed, such as toll plazas, rest areas and drive-thrus, meaning the system only makes use of vehicle energy that would be required to slow down.

A kilometer of “electric road” could generate enough power for 40 houses, and progress in the technology could generate enough electricity to feed the national power grid. Private companies were competing in this sector but recently governments of developed countries are also taking notice to the developments in turning traffic rush into electricity and are funding many projects.

Advantages of the Invention:
Followings are the advantages of the present invention:
(1) It is capable of producing very large amounts of electricity without increasing the consumption of any fuel.
(2) It is relatively inexpensive and easy to install.
(3) Piezoelectricity offers a clean and renewable base of some sort of power potentially useful.
The other objects and advantages of the present invention will become apparent to those skilled in the art in view of the description of the best presently known mode of carrying out the invention as described herein.
Conclusions:

The scientists claim that this can generate 2000 watts per hour in regular traffic, which would translate into a huge amount of implemented on the nation’s roads. O course, you would have to take into account the cost of introducing the technology but even if it only powered street lighting and traffic signals it would be a huge saving.

The above disclosure is not intended as limiting. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. In particular, although the method has been described as utilizing a roadway, any location that is subject to traffic, e.g. a parking lot, would be a suitable location for an installation of the device.

Accordingly, the above disclosure should be construed as limited only by the restrictions of the appended claims.

Future plans include placing the crystal generators in railways. Trains are advantageous in that they are guaranteed to apply pressure in the same place over and over again and the technology is also applicable to airport runways and rail systems.

Sabir Hussain Shah
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