Lasted edited by Andrew Munsey, updated on June 15, 2016 at 12:52 am.
Richard Dickson proposes using the piezoelectric effect for generating electricity, where pressure turns into electricity, from environments such as wave action or roadway impact. The question is one of cost and feasibility, not whether or not it would work.
There would have to be a large-scale manufacturing process developed using benign crystal materials, strung together electrically, for this idea to have practical merit.
A provisional patent has been filed.
This coverage is the only coverage on the net as of Nov. 20, 2006.
Piezoelectricity is the term for electrical current generated by mechanical stress, or pressure, applied to certain non-conductive solids. The effect was first discovered by the Jacques and Pierre Curie brothers in the 1880s. The Curie brothers applied pressure to common crystalline materials, such as cane sugar, salt, and quartz, and found that electrical charges appeared, and these charges were proportional to the stress applied.
Piezoelectric materials science has evolved from natural crystals, such as quartz, to exotic manufactured piezoceramic materials, which can produce various voltages under stress.
Subsequent developments in the field since then have led to the development of voltage source devices, sensors, and actuators. Perhaps the most well-known application is the car cigarette lighter, airbag sensor, and the common doorbell buzzer. But the technology has also been useful in sonar development, ultrasound medical and non-destructive inspection applications, as well as electronics equipment.
Currently, the latest research revolves around “power harvesting" from vibrations using piezoelectric materials. Power harvesting is the term used to describe the process of acquiring the energy surrounding a system and converting it into usable electrical energy. This research has been sparked for the need for wireless power sources for the new wireless technology (WiFi laptop computers, Ipods, cell phones, etc.). However, this research has been into mostly low voltage applications. [See Ref 1].
Power harvesting research has delved into piezoelectric applications mainly due to the development of powerful new composite piezoelectric ceramic materials. The lead titanate zirconate group and even newer lead-free ceramic materials seem to show the most promise for future applications over a range of compositions. [See Refs 2 &3]. Flexible PVDF materials are even more intriguing.
Ref (1): A Review of Power Harvesting from Vibration Using Piezoelectric Materials by H.A. Sodano, D.J. Inman and G. Park, Shock and Vibration Digest, Vol. 36, No.3, pgs 197-206 (2004).
Ref (2): Piezoelectric Ceramics by Hans Jaffe, Journal of the American Ceramic Society, Volume 41:11, Page 494, November, 1958.
Ref (3): Processing and Piezoelectric Properties of Lead-Free (K,Na) (Nb,Ta) 03 Ceramics, Journal of the American Ceramic Society, Volume 88:5, pages 1190-1196 (2005)
See Eight-page explanation and diagrams - includes much of the information that is contained here.
Mr. Dickson is pioneering ideas of using changes in pressure for power harvesting, and has an earlier invention, the “Directory:Dickson Hydrosphere", which converts hydrostatic pressure to electrical current via pressure differentials and secondary effects.
However, “piezoelectric mats" represent a more direct way to convert the resonating pressure in the ocean or lake water column into electricity.
Essentially, this patent pending idea consists of embedding shaped (round, square or rectangular) piezoceramics or layers of PVDF material, hereafter referred to as “piezoelectric cells", into sealed, rubber coated mats, which would then be linked together and placed on sea or lake beds at depth. The mats could be linked together via electric cable connections, and then spooled onto the wenches of cable laying ships for laying down a large array in oceans or lakes. The embedded piezoelectric cells are linked in series within the mats, so that the combined effect of all the electricity generated from the vibrating water pressure in the water column directly above the mats is harnessed and transmitted to shore via power cables on the sea or lake bed. Excellent locations would be areas of the oceans and lakes with relatively shallow, flat bottoms and with consistently high waves. This ensures a mobile water column and the requisite variable pressure required for the system to work. Candidates for placement of piezoelectric mat fields include most of the North Sea (conveniently located near major population centers), the Great Lakes (offshore near Chicago, Cleveland and Buffalo might prove ideal), the Georges Bank near Boston, Mass. and the Bahamas Banks near Miami, Florida (however, a deep ocean trench between Florida and the Bahamas might present problems for power cables transmitting the collected energy).
Possible land-based applications include embedding large arrays of piezoelectric cells in close proximity at key, high-traffic chokepoints beneath the nation's freeway system. Good locations would be high volume freeway off-ramps or key intersections. Considering that over a hundred million auto trips are made per day in the U.S., this is a considerable potential renewable, clean energy source that has been completely over-looked.
Additionally, auto and truck wheels could be designed (and possibly bicycles)to include piezoelectric cells embedded around the wheel axis with a mechanism for directing pressure onto each cell at the moment of road contact. If enough cells were used, this might generate sufficiently useful amounts of electricity to power batteries and electric motors.
In any case, due to the low voltage output (even lower than solar cells) of individual piezoelectric cells, ideas utilizing large arrays with piezoelectric cells connected in series are the only practicable options for use. However, this is not insurmountable, and analagous to similar problems with solar cells, since solar cells are also only commercially useful in large arrays due to their individual low-voltage output.
Dickson's idea would revolve around development of a large piezoelectric cell (50 cm x 50 cm) that could then be linked in series (much like solar cells are linked). The individual cells would incorporate layers of PVDF. Then with a raised,rubber-coated spring steel pressure ridge for contact at the pressure impact point, the device would work when pressure was exerted on the raised ridge, as this would strike the PVDF material across its entire area and thus generate electricity, since piezoelectric materials convert mechanical stress to electricity due to their crystalline nature. The advantages to a larger piezoelectric cell is that more electricity can be generated due to the larger crystalline surface exposed to the mechanical stress placed upon the cell.
This process is more complicated in the ocean or lake environment in terms of cell development (must be encased in leak-proof material and laid down via ship) but ashore, embedded under roadways in key sections (obviously not the whole roadway, as this would be too expensive and diffuse) at intersections or freeway on/off ramps, you could generate significant amounts of electricity given a large enough array (e.g., a mile or more). This electricity could then be funneled directly into the power grid of a city or town, or be used to power stoplights, traffic signals, and LED signs along the road way itself. In any case, it would recover a lot of potential energy that is currently being lost. Again PVDF materials would seem to lend themselves well to this type application.
The other idea was to place piezoceramics or PVDF materials around the axis of a wheeled vehicle (car, truck or bike). The materials would have to be arranged in such a way that at any point the tire is in contact with the road, the pressure point applies to just one individual piezoelectric cell. Then as the tire moves, another cell has pressure applied to it, and so on. This way you get continuous electrical output. This idea would not generate enough power to operate the vehicle, but would supply additional electrical power for periperhal equipment: lights, horns, stereos, etc. or could be used to charge an emergency power supply in the vehicle in case the main battery went down.
Also, another interesting idea would be to use vehicles themselves as a way of harvesting and collecting energy. This would be another variant of the roadway idea, but one in which the consumer would benefit personally and directly. It would entail using the piezoelectric wheels mentioned above, but instead of applying the electricity generated for direct vehicle use, collect it in auxiliary batteries within the vehicle from which it could then be transferred to electricity collection points. A device could be built that would collect the electricity at service stations via a plug-in transfer and power inverter. The electricity could then be sold and transferred to the local power utility via power grid connections. In fact there are even laws that compel utilities to purchase generated electricity, so there is already a guaranteed market. Of course the vehicle driver would receive remuneration in exchange for the amount of electricity harvested. The money could be dispensed either directly from the collection machine, since it would be in small amounts, or perhaps the money could be also applied toward gasoline/diesel fuel purchases via a computer link to the service station pumps. This would be an excellent way for vehicle owners to reduce their fuel costs by consistently collecting and selling electrical energy harvested from the environment. What a nice idea that everytime you take a car trip, you make a little money from friction, since from a physics point of view, vehicles with piezoelectric wheels are just collecting friction energy from the road that would otherwise be lost.
Finally, the wheel generators above could also be of more conventional design. Tradtional mechanical electrical generators are more efficient than piezoelectric generators, but the tradeoff is one of durability or longevity. Mechanical generators have moving parts, which can wear down or require repair over time. However, one way to overcome this is with a new type of simple, less complex mechanical generator. Mr. Dickson has a patent pending kinetic electrical generator (i.e., "Pancake Style Kinetic Energy Electrical Generator") that is very rugged in design, has fewer moving parts, and a unique split rotor, that orbits freely and radially about the stator in response to ambient kinetic energy from the environment.This device could be attached to vehicles between the wheel and shock absorption system in order to harvest vibrating motion from the roadway and convert it into electrical energy, and is extremely durable and efficient. Mr. Dickson has also submitted this device for NEC evaluation and a separate PES WIKI page ("Dickson's Human Kinetic Energy Electrical Generator").
Provisional patent applied for.
On Nov. 19, 2006, New Energy Congress member, Congress:Advisor:Kenneth M. Rauen said:
Piezoelectric generators need lots of pressure to work
effectively. Unrestricted motion will not be an
effective transduction process. The concept has merit
but needs work on a practical embodiment.
Directory:Piezoelectric > Directory:Wind > Directory:Rick Dickson:Wind Tree - Imagine harnessing the power of hundreds of leaves fluttering in the wind. Richard Dickson is developing a passive wind harvesting technology that uses piezoelectric materials woven into textile-like material to form artificial leaves for a bio-mimicking "tree".
3430 SE Harrison Street
Milwaukie, Oregon 97222
Email: [mailto:email@example.com?subject=Dickson_Piezoelectric_mentioned_at_PESWiki.com firstname.lastname@example.org]
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