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Piezoelectric energy generation in India: an empirical investigation. Piezoelectric solar panels

Piezoelectric energy generation in India: an empirical investigation. Piezoelectric solar panels

    Inexpensive, low-power piezoelectric buzzers would be built in.

    NASA’s Jet Propulsion Laboratory, Pasadena, California

    It has been proposed to incorporate piezoelectric vibrational actuators into the structural supports of solar photovoltaic panels, for the purpose of occasionally inducing vibrations in the panels in order to loosen accumulated dust. Provided that the panels were tilted, the loosened dust would slide off under its own weight. Originally aimed at preventing obscuration of photovoltaic cells by dust accumulating in the Martian environment, the proposal may also offer an option for the design of solar photovoltaic panels for unattended operation at remote locations on Earth.

    The figure depicts a typical lightweight solar photovoltaic panel comprising a backside grid of structural spars that support a thin face sheet that, in turn, supports an array of photovoltaic cells on the front side. The backside structure includes node points where several spars intersect. According to the proposal, piezoelectric buzzers would be attached to the node points. The process of designing the panel would be an iterative one that would include computational simulation of the vibrations by use of finite-element analysis to guide the selection of the vibrational frequency of the actuators and the cross sections of the spars to maximize the agitation of dust.

    Although the basic concept of the proposal is a straightforward extension of a common household cleaning practice, the engineering implementation of the proposal would not be trivial. The following are some of the engineering issues that must be addressed:

    • Compact, low-power, inexpensive piezoelectric buzzers are commercially available. They may or may not be suitable for use as the piezoelectric actuators to implement the proposal. Because typical commercial buzzers operate in the kilohertz frequency range and the natural vibrational frequencies of typical solar photovoltaic panels are lower, it may be necessary to build lower-frequency piezoelectric buzzers.
    • It may be necessary to cover panels with flat, transparent sheets or else redesign the panels to eliminate recesses or protrusions that could retain dust or prevent dust from sliding off during vibration.
    • The expected rate of accumulation of dust must be taken into account in assessing the effectiveness of a dust-removal design.
    • Tests must be performed to determine the interdependences among tilt angles required for interception of solar radiation, the amounts of agitation required at various vibrational frequencies and amplitudes to reduce obscuration by dust to an acceptably low level at those tilt angles, and the differences in among the rates of removal of dust particles of different sizes and types.
    • Care must be taken to ensure that the energy recovered by removing dust that obscures the solar photovoltaic panel exceeds the energy expended in shaking the dust off. This entails consideration of buzzer power levels and agitation times.
    • Care must also be taken to ensure that the dust-removal design does not adversely affect equipment other than the solar photovoltaic panel.

    This work was done by Stephen Dawson, Nick Mardesich, Brian Spence, and Steve White of Caltech for NASA’s Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at under the Machinery/Automation category. NPO-30909

    This Brief includes a Technical Support Package (TSP).

    Solar Array Panels With Dust-Removal Capability

    (reference NPO-30909) is currently available for download from the TSP library.

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    Piezoelectric energy generation in India: an empirical investigation

    The consumption of energy has always been in exponential growth and also there is always an increasing demand in the requirement of energy in some way or the other. So, there is a need to search for energy availability from alternate sources of energy. The utilization of waste energy of foot power with human locomotion is relevant and important for highly populated countries like India where the railway station, temples, etc., are overcrowded all round the clock. When the flooring is engineered with piezoelectric technology, the electrical energy produced by the pressure is captured by floor sensors and converted to an electrical charge by piezo transducers, then stored and used as a power source. This paper deals with the generation of alternate sources of energy through piezoelectric materials. This research describes the use of piezoelectric materials to harvest energy from people walking vibration for generating and accumulating energy. This study also studies the perceptions and adaptability of piezoelectricity. The adaptability of piezoelectric technology in a real-time environment has been studied by comparing the overall cost of generating electricity with solar energy. This study also suggests a footstep of the piezoelectric energy harvesting model which is cost-effective and easy to implement.


    In India energy constitutes 52% of the commercial and industrial respondents. With the yearly rise in the demand for electricity throughout the country it is high time that we think about generating cleaner sources of electricity. For this already the Indian power sector has taken various initiatives to promote renewable sources of power like solar, wind, hydro, etc. through policies and schemes that overall benefit the entire stakeholders. But still, there need many more ways through which electricity can be generated.

    For an alternate method to generate electricity, there are a number of methods by which electricity can be produced, out of such methods footstep energy generation can be an effective method to generate electricity.

    Considering the daily emerging demand for power and the global climatic changes there is a heavy requirement of cleaner sources of power before it is too late. Also, India has set targets of achieving 175 GW of power by 2022 only through renewable forms of energy. Keeping in mind the above ambitious targets that countries are putting forth regarding the cleaner sources of fuel, there is an urgent requirement of alternate sources of power that not only satisfies the requirement but also meets the financial, adoption, and implementation into the real-time scenarios as well. Below, the shares of energy generation in India are shown (Table 1 and Figure 1).

    Total power production in India (as on 31.01.2020).

    piezoelectric, energy, generation, india, empirical
    FuelMW% of total
    Total thermal 2,30,189.57 63.2%
    Coal 1,97,964.5 54.2%
    Lignite 6,760 1.7%
    Gas 24,955.36 6.9%
    Diesel 509.71 0.1%
    Hydro (renewable) 45,399.22 12.6%
    Nuclear 6,780 1.9%
    Renewables 86,321.03 22.7%
    Total 368,689.82

    Power capacity in India till Jan’2020. (Source:CERC 2020).

    The piezoelectric effect

    The piezoelectric effect was discovered in 1880, by two French physicists brothers Pierre and Paul. A piezoelectric sensor is a device that uses the piezoelectric effect to measure pressure, acceleration, and force by converting them to an electrical signal (Figure 2). When pressure is applied to piezoelectric crystals electricity is developed over the crystal lattice.

    Piezo power with force direction. (

    Characteristics of piezo electricity

    These days most of the research in the energy field is to develop sources of energy for the future. It is time to find renewable sources of energy for the future. Piezoelectric materials are being more and more studied as they turn out to be very unusual materials with very specific and interesting properties.

    Energy can never be created nor destroyed; it can only be transferred from one form to another. In fact, their materials could produce electrical energy from mechanical energy and may convert mechanical behavior like vibrations into electricity. While recent experiments have shown that these materials could be used as power generators (Figure 3).

    Piezoelectricity properties layout. (Source: Compiled by the author).

    Factors leading to requirement of piezo electricity

    Below, Figure 4 shows the basic factors that lead to the requirement of the piezoelectricity.

    Factors of piezoelectricity. (Source: Compiled by the author).

    Important components of piezoelectric tile

    Piezoelectric sensor

    A sensor that utilizes the piezoelectric effect, to measure changes in acceleration, strain, pressure, and force by converting them into electrical charge is called a piezoelectric sensor. This generated piezoelectricity is proportional to the pressure applied to the solid piezoelectric crystal materials.


    A Battery is an array of electrochemical cells for electricity storage, either individually linked or individually linked and housed in a single unit. An electrical battery is a combination of one or more electrochemical cells, used to convert stored chemical energy into electrical energy. An electricity is used to be generated and consumed at the same time, hence batteries are used as a storage device for storing electricity.

    Primary battery

    Primary batteries can produce current immediately on assembly. Disposable batteries are intended to be used once and discarded. These are mostly used in portable devices such as in alarm and communication circuits where other electric power is only intermittently available.

    Secondary battery

    Secondary batteries must be charged before use; they are usually assembled with active materials in the discharged state. Rechargeable batteries or secondary cells can be recharged by applying electrical current, which reverses the chemical reactions that occur during its use. Devices to supply the appropriate current are called chargers or rechargers.

    Piezoelectric tiles

    Piezoelectric floors (Figure 5) are designed to capture the wasted energy and resources and store or redistribute them where they are needed. Energy is generated when a person steps on tiles that feature piezoelectric attributes. This kinetic energy is converted into electricity (Figure 6).

    Piezoelectric tile layout. (Source:Shreeshayana et al. 2017).

    Block diagram of piezoelectric tile. (Source:Naresh et al. 2018).

    Literature review

    Electricity from footsteps, SS Taliyan, BB Biswas, RK Patil, GP Srivastava, TK Basu, 2010. This paper discusses the basic engineering and operational mechanism of piezo crystal, engineering analysis of the model, working of piezo crystal and energy generation through footsteps.

    Potentials of piezoelectric and thermoelectric technologies for harvesting energy from pavements, Lukai Guo, Quing Lu, 2017. This paper discusses the cost-effectiveness analysis of energy harvesting pavement technologies. It estimates electrical energy generation from a pavement network by two technologies cost calculation and estimating needs. Cost analysis and estimation of energy production based on piezoelectric technology.

    Floor tile energy harvester for self-powered wireless occupancy sensing, Nathan Sharpes, Dušan Vučković and Shashank Priya, 2016. This paper presents details about designing and optimum structure of the piezoelectric product. Also proposed a suitable structure for product design for commercialization and design of outer shell circuit design and structure.

    Green sidewalk makes electricity – one footstep at a time, George Webster, 2011. This paper studies the power generation method. Reviews of the public and studies introduction of an alternate source of energy in the market.

    An Investigation into energy generating tiles – Pavegen, Zhen Liang Seow, Song Tao Chen, and Nor Bainin Khairudin, 2011. This paper provides an idea of commercialization of the piezoelectric based energy production in a live scenario.

    Future uses of the piezoelectric effect for energy production, Zack Mester and Guilherme Tamassia, 2012. This paper discusses the economic aspects of piezoelectricity, drawbacks of piezo electricity and other innovative techniques of piezoelectric generation. Also studied how to minimize the potential drawbacks of piezoelectricity and improve the efficiency of energy generated.

    Feasibility study for using piezoelectric energy harvesting floor in buildings’ interior spaces, Adnan Mohamad Mahmoud Yousif, 2017. In this paper, the feasibility of piezo electric tiles in the interior of buildings is studied. Analysis of energy transformation with the help of piezo electric tiles is done. Also studied the feasibility of energy-generating tiles in the interior of buildings and also at low pedestrian spaces like apartment case by using harvesting floor tiles in a different way to generate and save energy.

    Application of piezoelectric transducer in energy harvesting in the pavement, Xiaochen Xu, Dongwei Cao, 2017. This paper states that utilizing piezoelectric technology in road energy harvesting is feasible and has a bright future. It defines the working mechanism in detail and the use of piezoelectric in energy harvesting.

    Electricity from footsteps, S.S. Taliyan, B.B. Biswas, R.K. Patil, and G.P. Srivastava, 2013. This paper presents the possibility of the generation of electricity from footsteps. Working model of the footstep-based energy generator. The article has given a detailed working model and functioning of the footstep-based electricity generating system. This is an energy-efficient way of producing electricity as walking is one of the most common things, we do in the day to day life.

    A review of power harvesting from vibrations using piezoelectric materials, Henry A. Sadano, Daniel J. Inman, and Gyuhae Park, 2004. This paper analyzes harvesting power from vibration using a piezoelectric material. Various aspects of energy harvesting based on mechanical and electric components are investigated. With the advancements in technology harvesting, electricity with the help of piezoelectric materials will be more efficient.

    Energy harvesting through the piezoelectric effect at sports venues, Julius Evans, 2015. This paper studies the various parameters related to consumer behaviour and adaptability of the tiles.

    Footsteps: Renewed tiles, Fatima Zahra Bouzidy, 2017. This paper carries out a detailed STEEPLE analysis of piezoelectric energy.

    Background of the study

    The recent study has revealed that an alternate source of energy is desperately required to meet the emerging future energy demands. Hence to meet the requirements a financially stable and viable source of power is required that will be environment friendly and possess a very easy methodology of producing energy. Hence the piezoelectric model justifies the study for an alternate source of power generation. Through the literature study, various parameters for considering the piezoelectric tile to be used as an alternate source of energy were identified like power availability, usage pattern in an area, cost of a unit of power, and overall electricity bill of a consumer. Few parameters identified were awareness about piezoelectricity, the willingness of producing standalone power. The above parameters have been studied in detail for meeting the core objectives of the research.

    Purpose of the study

    This study is undertaken to study the various parameters of piezoelectric tile to be used as an alternate source of energy, study consumer perceptions, response, adaptability of piezoelectricity, and also analyze the unit cost of electricity under piezoelectric.


    This study is a mixed study. In this study, primary data is collected using non-probability sampling method, where the respondents from different sections especially those who are having the basic ideas about the trending technologies in the market were selected. The futuristic ideas that are prevailing in the current technological market especially in the sector of engineering and power. This was required as many factors were felt necessary to come up with a conclusion based upon the output received by the samples. Not only based upon the behavior of the consumer but also the market requirements were focused upon while analyzing or studying the samples. For collecting data questionnaire is prepared based on variables and also three-point likert scale is used. In this study, 143 respondents were selected. The survey was done using Google sheets. For collecting qualitative data personal interview using face to face Skype mode is used. Further, the Delphi method is also used by selecting two industry experts.

    Data analysis

    Data analysis is done as per objectives. To achieve the first objective the following questions are used for collecting data and then these data are being analyzed.

    Question 1. Do you have frequent power cuts in your house/area?

    Question 2. Do you save electricity by switching off the appliances whenever they are not required?

    Question 3. What is the cost per unit you pay for your electricity bill a month?

    Question 4. How much do you pay for your overall electricity consumption in a month?

    To achieve the second objective the following questions are used for collecting data and then these data are being analyzed.

    Question 1. Will you opt for generating electricity by walking?

    Question 2. Are you interested in producing power on your own?

    Question 3. Have you heard about piezo electricity?

    Question 4. How did you come to know about this technology?

    Question 5. Do you wish to have new electronic flooring tiles installed in your home?

    Question 6. How often do u walk a day?

    Question 7. Which exercise do you prefer doing regularly?

    Question 8. How much will you prefer in investing in gadgets that can generate electricity for households?

    piezoelectric, energy, generation, india, empirical

    To achieve the third objective cost analysis is prepared and compared with solar energy. A layout of cost analysis is as given below (Table 2):

    Total cost of piezoelectric tile and output in India.

    Overall cost (one piezoelectric tile) (Rs) ₹ 12,511
    Average steps per day Nos. 7000
    Total hits (assuming 3 hits per person in a house) Nos. 21,000
    Energy per step Joules 5 J × 4 nos of piezo crystals = 20 J
    Total energy per day (J) Joules 420,000 J
    Total energy per day (kWh) kWh 0.11664 kWh
    Total energy per year kWh 42.573 kWh
    Durability Years 15 years

    Also, further the piezoelectric power produced is compared with solar energy that stands currently as an emerging alternate renewable source of power which is also highly commercialized (Table 3).

    Comparison of solar power with piezoelectric power.

    Solar powerPiezo based power
    Cost of installation of 1 kW Rs 75,000 Cost of one tile Rs 12,511
    Number of units produced in one year (considering CUF-20%) 1752 Units Number of units produced by one tile in one year (considering 21,000 footsteps) 42.573 Units

    Result and discussion

    It is clear from Figure 7 that 21% of respondents have the opinion that there are frequent power cuts in the area. 96% of respondents do have the habit of switching off the appliances when not required, while still, 4% of the respondents do lack in the same habit (Figure 8). Nearly 40% of respondents pay the electricity bills in a range of Rs 3–5 and above Rs 5 per unit of electricity consumption a month (Figure 9). 77% of respondents get above Rs 1000 as their overall electricity consumption a month, 18% pay above Rs 500 per month and the remaining get their electricity bill below Rs 500 (Figure 10).

    Power availability in area.

    Piezoelectric Materials – The Most Common Unknown Power Source

    With new practical applications being developed every day, the piezoelectric industry is expected to reach roughly 41 billion within the coming three years, with a compound annual growth rate of nearly 6%. This boom will allow for the further development and implementation of high-tech amorphous and film-based piezoelectric polymers in the modern world.

    What are Piezoelectric Materials?

    Piezoelectric materials allow for us to harness kinetic energy, by transforming force into an electric charge. First defined by the Curie brothers in 1880, Piezoelectricity has become a fundamental principle exploited in modern technology.

    Piezoelectricity refers to a substances ability to produce an electrical charge when mechanical stress is applied. This electrical charge is produced by forced asymmetry. In piezoelectric materials, positive and negative charges are separated from each other, while remaining aligned in a symmetrical pattern. When mechanical stress is applied to the substance, this symmetry is lost, resulting in the production of an electric charge.

    Another unique property of the materials is the random nature and presence of Weiss domains (magnetically oriented without external magnetic influence).

    It was later discovered that these same materials demonstrated a direct inverse property to the electric effect. It was found that if an electric charge was applied to the material, repeatable mechanical deformation would occur within the material. This discovery gave great utility to such materials, as it essentially doubled their prospective use-cases.

    Manufacturers and Innovators

    Before we dive in to examples of real-world use-cases, the following are a trio of leading companies that leverage piezoelectric materials throughout a variety of products integral in modern electronics.

    Notably, analysts for Barron’s currently list each of the following stocks as either ‘over’ or ‘buy’.

    Stoneridge (SRI)

    Listed on the NYSE, Stoneridge (SRI) has seen its shares increase in value over the past year by more than 30% at time of writing. While revenue at Stoneridge took a hit during the height of COVID, 2021 saw a nearly 20% rebound to 770M

    Stoneridge employs over 5,000 people, and operates out of the State of Michigan.

    Methode Electronics (MEI)

    Listed on the NYSE, Methode Electronics Inc. has seen its shares increase in value over the past year by nearly 15% at time of writing. Over the past 4 years, Methode Electronics has managed to continue growing its revenue between 2.36% and 10.13% each year. For 2022, revenue topped 1.16B.

    Methode Electronics employs over 7,000 people, and operates out of the State of Illinois.

    Kimball Electronics Inc. (KE)

    Listed on Nasdaq, Kimball Electronics Inc. has seen its shares increase in value over the past year by more than 32% at time of writing. Where the companies listed above struggled from 2019-2020, Kimball Electronics managed to continually boast increasing revenues. Totaling 1.35B for 2022, this marks a 4.47% increase over 2021.

    Kimball Electronics employs over 7,000 people, and operates out of the State of Indiana.

    Modern Advancements

    Traditionally, naturally occurring piezoelectric substances were used to demonstrate the effect. Most commonly, the material of choice was quartz. When the limits of naturally occurring substances were reached, man-made ceramics became the popular choice. Designed in 1952, and still one of the most popular piezoelectric ceramic today is PZT (lead zirconate titanate). However, with drawbacks such as limited deformation, fragility, and a high mass density, PZT is not ideal for every application.

    In 1964 PVDF (poly vinylidene fluoride) was developed. PVDF has a semi-crystalline structure and creates charges several times greater than quartz. Although this man made polymer addressed many of the drawbacks of PZT, it had various of its own – piezoelectric breakdowns at high temperatures, and degradation. With recent technological advancement and increasing demands, PZT and PVDF may have reached their limits.

    In the early 2000’s institutes such as GAIKER-IK4 began to develop what are known as amorphous piezoelectric polymers. By utilizing an amorphous structure, much higher temperatures can be endured by the substance. Since the piezoelectric effects are not relying on the crystalline structure which breaks down at higher temperatures, the amorphous structures make for a much more rugged polymer.

    These amorphous polymers are being developed because they offer higher levels of deformation, large weight reduction, and greater ruggedness. By achieving this, the field of applications for the materials now allows for the incorporation of aerospace and electronic devices. With the new amorphous piezoelectric polymers and films being developed, failure during use will occur at temperatures of roughly 150°C and greater. Degradation of the substance will occur at roughly 400°C. While this may limit their use in extreme conditions, the vast majority of applications fall within an appropriate range.

    Like many new substances, these polymers are being developed by using PVDF and PVT as the fundamentals. Attempting to keep positive attributes from each material while eliminating as many disadvantages as possible. Although such products are newer polymers, they are modeled after the current working models.

    By utilizing an amorphous structure, extensive testing must be done on optimum vitreous transition temperatures. This value is directly linked to the strength of piezoelectric properties the material will possess. The amorphous structure demonstrates and relies on short range order to produce a piezoelectric effect instead, of long range order as seen in crystalline structures. In addition to this, many are opting to incorporate polyimides into the structure of the materials due to their mechanical, dielectric, and thermal properties, with the polyimides ensuring poling of molecules regardless on their positioning.


    Past and current applications of piezoelectric materials include many inconspicuous items such as lighters, quartz clocks and even engine management systems. The most common use for them currently would be in sensors and actuators. While suitable piezoelectric materials have been applied for these use cases, future applications demand a more versatile material. Thankfully developing piezoelectric polymers are just that – versatile. With constant advancements in our understanding of material science, and their ability to display direct inverse effects, the number of applications in which they can be used continues to increase. Some intriguing present and potential future applications include,

    Mobile and Wearable Electronics

    Talk powered cell phones and wearable devices. By utilizing the pressure created within the microphone due to sound waves, piezoelectric polymers can hopefully one day create enough power needed to use the phone. While it is unlikely that this concept will remove the need for a battery altogether any time soon, it does create the possibility of extending battery life in low-drain wearable Smart devices.

    It should be noted that piezoelectric materials have been used in microphones for nearly 100 years at this point. Rather than the end goal being to charge a device though, these applications allow for the conversion of soundwaves in to electricity for the purpose of recording and playback in a cost-effective manner.

    Dampening Systems

    Another application is the use of piezoelectric materials in dampening systems. Companies such as HEAD have incorporated this idea into its tennis rackets and skis in an effort to absorb/dampen vibrations. When an impact occurs on the racket or ski, the reciprocal effect is harnessed by sending the electric signal created to an inverse material providing an opposing force. This results in an effective dampening system.

    This same concept is being applied to noise and vibration reduction in cars, homes, and in hazardous workplace environments. One example of such an environment would be Bitcoin mining farms. Not only are vibrations harmful to electronic equipment over the long run, there have been various instances of surrounding communities in which these operations take place complaining about the resulting noise and vibrations resulting from the use of ASIC devices. In many similar scenarios, piezo-based actuators are used as a solution to dampen each of these effects. With sound waves being created in cars, homes, and machinery by materials reverberating, this noise can also be eliminated, or at least reduced, with traditional methods such as an adhesive dampening material. These materials work passively though, and are very heavy and expensive. They typically work by lowering a materials resonant frequency. Exploiting the properties of piezoelectric polymers solves this problem by taking the more active and dynamic approach described above.

    Cleaning Solutions

    To demonstrate just how versatile the use cases for piezoelectric materials are, consider work being done by companies like Solar PiezoClean. In this instance, the company is coating solar panels with a piezoelectric film. The purpose is to offer a low maintenance means of keeping solar panels clean – a key to ensuring optimal efficiency.

    This process involves applying an electric charge to the film, which then vibrates at a specific frequency and pitch that allows for dust and dirt to simply fall off with help from gravity. What this all means is savings in water and manpower, while increasing longevity and efficiency of coated panels. A simple, but ingenious solution to a problem that is only growing as solar installations become more commonplace.

    common implementations of piezoelectric materials in such a manner include ultrasonic cleaning devices like jewelry cleaners.


    Earlier we mentioned the use of piezoelectric materials within the aerospace sector. Here, planes can make use of such materials to monitor structural integrity and stressors through the measurement of electric charges produced – a use case that can allow not only for increased safety, but greater efficiencies by allowing for engineers to simultaneously cut weight and strengthen structures where needed.

    piezoelectric, energy, generation, india, empirical

    Move beyond our atmosphere, and piezoelectric actuators are used in many satellites. The ability to operate with extreme precision allows for such actuators to make micro-thrusters capable of proper satellite positioning.

    HealthCare Diagnostic Tools

    As our ability to create smaller and smaller devices improves, we are now using piezoelectric materials in various diagnostic tools within healthcare. An example of this is Intravascular Ultrasound (IVUS). IVUS is a process which allows for tiny probes to generate imaging from within blood vessels. This is done through the use of ultrasound transducers built with piezoelectric single crystals.

    Piezoelectric materials are also used in certain dentistry equipment. Similar to the cleaning solution being utilized by SolarClean described above, this equipment relies on ultrasonic waves, produced by applying an electrical current to the piezoelectric materials, to clean/remove plaque from teeth.


    Sonar (Sound Navigation and Ranging) systems can be used to provide imaging, or for communication. Examples of imaging include topographic mapping of ocean floors, or every-day fishfinders. Meanwhile communication can be achieved through the creation of sound waves. Each of these processes are made possible through the use of piezoelectric transducers.

    Despite being developed over 100 years ago, Sonar continues to play an important role today. The most recent widespread example of this would be its implementation in self-driving cars, which typically use a combination of Sonar, LIDAR, and radar to track and interpret surroundings.

    Energy Harvesting

    Finally, a very intriguing application would be large scale energy production. Piezoelectric polymers are being developed to place in high traffic areas, including various factories, sport fields, train stations, and more around the world. A 1cm 3 piece of quartz is capable of producing up to 4,500V of electricity when 175lbs of force is applied. With each footstep to hit the ground in such stations creating this electricity, there is the potential to harness huge amounts as it is created daily – greatly increasing efficiency and electricity costs for the building.

    Beyond foot traffic, many have envisioned a future in which roadways are embedded with such materials, creating electricity to power street lights and signs as cars exert physical force on them.

    When combined, future technologies like wireless car charging being developed by Electreon, and powered surfaces by companies like Pavegen, will hopefully one day allow for reduced battery sizes in vehicles, and a much more efficient and clean way to keep electric vehicles charged.

    Final Word

    Overall, the potential of piezoelectric materials is just beginning to be realized. Photovoltaic effects that make Solar energy possible were discovered in the mid-1800’s, and are only now becoming practical for widespread use. Piezoelectric materials are no different, and as research and development in to these materials continues, increases in efficiency and durability follow suit. Modern scientific advancements are only now allowing us to realize, or at least understand, the full potential of this source for energy, with the use-cases listed here (electricity generation, sound dampening, sonar, sensors, acutators, etc) being only a select few out of countless possibilities.

    Piezoelectricity Is the Renewable Energy We’ve Been Waiting For

    First discovered by Pierre Curie, the husband of Marie Curie, and his older brother Jacques in 1880, piezoelectricity works by taking an electrically neutral substance such as particular crystals, ceramics, and even biological materials and applying enough pressure to create an imbalance of positively and negatively charged atoms on opposite sides. Under normal conditions, the arrangement of the atoms balances out the electric charge, but under pressure, an electric field can be created because the neutral arrangement has been disfigured, leaving a higher concentration of positively charged atoms on one side and negatively charged atoms on the other.

    The piezoelectric effect has a variety of applications today, such as in quartz watches, BBQ lighters, guitar pickups, clocks in electronics, inkjet printers, etc. The reason you have to push the button so hard on BBQ lighters, for example, is because you’re actually slightly deforming a quartz crystal, which creates an electric charge that is then forced to jump a tiny gap, creating a spark and igniting the lighter fluid.

    So if any sort of movement has the potential to become source of electricity, why are we not using this more often? In the last few years, researchers have been working on implementing piezoelectric materials into the human body, roadways, bike paths, sidewalks, solar panels, etc. to unlock this relatively untapped source of renewable energy.

    Shock to the Heart

    In a paper published in Nature, Professor Ehud Gazit and his team from Tel Aviv University demonstrated their use of the piezoelectric effect to convert both voluntary and involuntary body movements to an internal electric current strong enough to power medical devices. Everything from bowel movements to the expansion and contraction of the lungs is a potential source of energy. They claimed that “The piezoelectric effect in proteins is an intriguing phenomenon that can potentially allow a better interface between the semiconductor and biological worlds.”

    This idea isn’t new, but its uses were limited because researchers couldn’t find materials that were both safe and electrically efficient. The most common piezoelectric material used commercially is lead zirconate titanate, a type of ceramic, which of course contains lead, making it toxic. However, Gazit et al. engineered a nanomaterial material that mimics collagen, the most prevalent protein in the body. Through their clever use of self-arranging peptides, their new material produced an electric current that rivals or possibly exceeds commercial materials. They said “we fabricated a simple biopiezoelectric device made from collagen-mimicking ultra-short peptide sequences that could achieve high current and voltage output, similar to that obtained using nanogenerators comprising inorganic materials or organic polymers.”

    Therefore, thanks to piezoelectricity, new medical devices will have their own safe power supply, allowing for longer-lasting and more advanced pacemakers, defibrillators, blood sensors, drug delivery systems, and whatever else is coming with next-generation medical devices.

    On the Road Again

    Given the amount of cars and buses on the world’s highways and the amount of people using sidewalks and bike paths, it’s safe to say that a staggering amount of energy could be collected through piezoelectricity. Every time a car exerts a force on the roadway, a pedestrian steps on the sidewalk, or a cyclist rolls down a bike path, this mechanical energy could be converted to electricity. Fortunately, researchers are working on it.

    For example, a research team from Lancaster University is testing a variety of piezoelectric materials and configurations, and the initial results look promising. They found that under normal traffic conditions (2000 to 3000 cars per hour) they can generate around 2 MW per kilometer of road, enough to power 2000 to 4000 street lamps. Taking into consideration the cost of installing this new energy collecting technology, the researchers believe they could save the city 20% of its cost to electrify their roadways. Lead researcher Professor Saafi said “The system we develop will then convert this mechanical energy into electric energy to power things such as street lamps, traffic lights and electric car charging points. It could also be used to provide other Smart street benefits, such as real-time traffic volume monitoring.”

    Similarly, California has invested 2.3 million on two projects to test the viability of harvesting energy from the mass movement of people. One of these projects is a 60 meter long stretch of road near the University of California, Merced. This roadway will be peppered with 2 centimeter wide stacks of piezoelectric ceramics. The other project is run by Pyro-E, a San Jose based LLC, and with a similar strategy they believe they can generate enough electricity to power 5000 homes. If scaled up, they believe “the power generated could provide 60% rate-reduction from retail electricity to help offset the adverse environmental impact of gasoline vehicles.”

    Furthermore, researchers have been pushing forward with paving roads with solar panels. If/when this happens, it turns out that piezoelectricity can make them more efficient. In a paper published by the Royal Society of Chemistry, the authors demonstrated that solar cells made with CH3NH3PbI3 change their efficiency when compressed. They claim that “While an external strain is applied in the CH3NH3PbI3 layer, the performance of the PPSC [piezo-phototronic organic perovskite] improves linearly.” Therefore, a roadway paved with solar cells would be great, but a roadway paved with piezo-solar cells would be much more efficient, with the more strain the better.

    Of course, all of this adds to the cost of maintenance and installation, but researchers are confident that new materials and configurations can turn enough of a profit to make it worth while.

    Blowing In the Wind

    Harnessing the wind is best done through air turbines, but even with the best designs energy is still left on the table. All structures exhibit As air flows around a structure it can become turbulent due to a process known as vortex-induced vibrations (VIV), in which air is forced to bend according to the curvature, in some cases creating a vortex on the structure’s surface. When this doesn’t happen symmetrically, the structure vibrates. When the vibrations match the structure’s resonant frequency, the structure oscillates heavily. Likewise, the galloping wind effect can be another source of energy. As strong wind pushes into and a around a structure, it exerts forces that compete with the structure’s natural elasticity, causing large oscillations.

    Researchers believe energy from both VIV and the galloping wind effect can be tapped. A team of researchers from China demonstrated in a paper from the Journal of Sensors that a “square cylinder” is an ideal shape for generating piezoelectricity from the wind. As this shape is hit by the wind, it oscillates, compressing piezoelectric ceramics at its base, producing a current. The authors said that “It is worth noting that both vortex-induced vibration and galloping of a square-section structure can be utilized in the same piezoelectric wind energy harvesting equipment, because both of the two phenomena can cause large oscillating amplitude that can be good power source to excite the piezoelectric device to vibrate.” They envision implementing their idea into already existing wind energy devices, adding to their efficiency by harnessing energy that would’ve otherwise gone unused.

    Is Piezoelectricity Worth It?

    Piezoelectricity has faced an uphill battle with large-scale implementation. For one, piezoelectric materials are sensitive to high temperatures, in that they become less efficient when subjected to heat. Second, piezoelectric crystals are water soluble, meaning they must be protected against the elements, creating additional costs. Third, and most importantly, piezoelectricity doesn’t produce enough output to compete with other forms of energy creation.

    However, the field of piezoelectricity is pushing forward quickly, creating better materials and configurations. For example, the US Navy just invested a few million dollars to develop “next generation piezoelectric single crystal materials” which is likely to result in piezoelectric materials with far greater output and durability. Because of research like this and the others discussed above, in only the last few years, we’ve seen numerous advancements that’ve made this form of energy creation increasingly more attractive. So membranes that can power internal medical devices, roadways that light themselves, and more efficient wind turbines, are just a few examples on a growing list of applications.

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