1. 2012 International Conference on Innovation and Technology for Sustainable Built Environment (ICITSBE 2012)
16 – 17 April 2012, Perak, MALAYSIA. Ref No : GT –23.
PIEZOELECTRIC EFFECT IN ENERGY HARVESTING FLOORING
SYSTEM: A LITERATURE REVIEW AND FEASIBILITY STUDY
Ahmad Haqqi Nazali Bin Abdul Razak 1, Abu Bakar Abdul Hamid2
1
Pusat Pengajian Senibina Dalaman, Fakulti Senibina, Perancangan & Ukur, 40450,
UiTM Shah Alam, Selangor, Malaysia. haqqi250@perak.uitm.edu.my
2
Pusat Pengajian Senibina Dalaman, Fakulti Senibina, Perancangan & Ukur, 40450,
UiTM Shah Alam, Selangor, Malaysia. abah7591@salam.uitm.edu.my
Abstract
Prices of global energy have significantly increased in the recent years as demand rose sharply and supply is
limited. Engineers, scientists and researchers are seeking for various alternatives and solutions towards the
global energy crisis. Concurrently, key players of the architecture, building and construction field are also
affected by this matter; not including the increasing price of raw materials but concentrating on sustainable
building energy consumption. Regenerative energy has recently been viewed as an alternative to renewable
energy especially to designers and architects across Europe. Regenerative energy established upon
piezoelectric effect borrowed from the sensor and transducer development field holds the key towards potential
solutions in harvesting energy from human motion. Prior to the introduction of piezoelectricity in pedestrian
energy harvesting field, researchers and designers have ventured into various study to capture these loss
energy. Many methods have been studied such as hydraulic generators (Risen, 2006); heel strike generators
(Chapa, 2008 and Ahira, 2008) and dynamo (Wright, 2007). Unfortunately, the study on this potential energy
harvesting technique is still at its infant stage; hence an in-depth literature searching is crucial prior to the
necessary experimentation on the piezoelectric effect. Pioneering research on piezoelectric effect has shown
significant positive result but the developments are widely on the sensor and transducer field. Henceforth this
study aims to accommodate the technology inside the building construction sector’s green technology.
.
Keywords: Piezoelectric, energy harvesting, green technology, sustainable interior, regenerative energy.
1.0 Background to Research
The question of reaping energy from human motions arises from observation made by the researcher on the
possibility to capture energy loss from a walking man. Vast literature searching have resulted in a promising
method; piezoelectric effect. Piezoelectricity is widely known to engineers and pure science researchers but a
strange term to architects, interior designers and building construction personnel. The concept of piezoelectric
effect can be achieved by adopting a smart material or piezoelectric materials and is described as the relation
between a mechanical stress and electrical voltage in solids. This process is two-way; where and applied
mechanical stress generates a significant amount of voltage as well as vice versa, applied voltage may shape-
shift the solid. Piezoelectricity or smart materials was discovered by Jacques and Pierre Curie in 1880 where
they found that these materials exhibit unique and interrelated properties. According to Fraden (1996), this smart
material has since became basis to a large number of sensor and transducer application in diverse fields such as
security systems, medical diagnostics devices and non-destructive testing.
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2. 2012 International Conference on Innovation and Technology for Sustainable Built Environment (ICITSBE 2012)
16 – 17 April 2012, Perak, MALAYSIA. Ref No : GT –23.
Daisuke (2009) further explains that the piezoelectricity is an effect from a surface electrical charge generated
when a certain stress is applied on a smart material. This phenomenon has been successfully been implemented
in areas such as ignition system, sonar, acceleration and gyro-sensors. Another technique being implemented
from piezoelectric effect is to generate electricity which Daisuke considers as an ―untapped energy‖ similar to
wind and tidal energy. He continues to discuss the energy harvesting technique can be implemented from
vibrations created in structures like bridges and railway stations.
It is also known that piezoelectric effect only occurs in non-conductive materials; mainly in crystals and
ceramics. Patel (2010) indicates that PZT (lead zirconate titanate) based ceramics are the most commonly used
smart materials due to the amount of electrical charges built up on both sides of this material compared to
others. This unique property of piezoelectric effect can be utilized to capture energy from environmental
vibrations such as human motion.
2.0 Problem Statement
Several studies and attempts are initiated to reap this potential energy from human motion. In Central London,
engineers modeled a system at Victoria Station to harvest energy from 34,000 travellers hourly and the
experiment resulted in 6,500 lit light bulbs (Risen, 2006). Ahira (2008) stated that under floor generators could
also be used to convert pedestrian footstep into electricity. Several shopping centers and railway stations across
UK were installed with these generators. ―Heel-strike‖ from pedestrians compressing pads installed beneath the
floors drives fluid through mini-turbines to produce electrical energy. The generated electricity is then stored in
batteries used to power lighting systems. Risen (2006) indicated an experiment initiated by a London based
architectural company to capture and convert vibrations into electricity via installed small hydraulic generators
in the floor. In 2007, James Graham and Thaddeus Jusczyk introduced ―Crowd Farming‖ concept in
Masssachussetts Institute of Technology (MIT) that could convert mechanical energy of people walking or
jumping into an electricity source (Wright, 2007). Their proposal won the first place in the Japan-based Holcim
Foundation’s of Sustainable Construction Competition. The concept of Crowd Farming is made of blocks that
depress slightly under the force of human steps. Furthermore, a British consultancy firm installed miniature
―heel-strike‖ generators underneath the stairs of Spinnaker tower in London to capture the energy generated by a
person walking up and down the stairs.
In addition, Bergeron (2009) listed numerous demonstrations on energy harvesting using piezoelectric effect
from sidewalks to combat boots. Stresses on piezoelectric materials generated by pedestrians’ movement on
sidewalks are converted into electrical charge; whereas the latter shows that piezoelectric elements embedded in
the heels of the combat boots are able to convert the bouncing and pounding of the heel-strike to reusable energy
specifically to charge batteries. Similar research is also stated by Howells, (2009), Wright (2007) and Richard
(2006). The technology of combat boot mini generators were first developed by DARPA (Defense Advanced
Research Projects Agency) in the United States under the project called Energy Harvesting which attempted to
power battlefield equipment for US Army.
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3. 2012 International Conference on Innovation and Technology for Sustainable Built Environment (ICITSBE 2012)
16 – 17 April 2012, Perak, MALAYSIA. Ref No : GT –23.
3.0 Research Objective
1. To investigate the best piezoelectric material and design for harvesting energy from human motion.
2. To measure the electrical energy output from objective (1) and improvise the design.
3. To develop a cost effective and working prototype of the energy harvesting module based on
objective (2).
4.0 Literature Review
Potential energy harvesting techniques are discussed by researchers, activists and designers globally. There have
been several endeavours to harness this potential reusable energy. Researchers have embarked into mini
generators (Risen, 2006; Richard, 2007; Wright, 2007) dynamo concept (Wright, 2007), ―heel strike‖ pressure
pad (Ahira, 2008), hydraulic system (Chapa, 2008; Ahira, 2008), piezoelectric effect (J. Kymsis, 1998; Chapa,
2008; Bergeron, 2009). Among these experimental attempts, piezoelectric effect by means of piezoelectric
material has been explored the most in harvesting reusable pedestrian energy.
The viability of piezoelectric effect in energy harvesting has also been discussed by Patel (2010) explaining a
previous study model by Starner (1996) showed that 5 Watt of electrical power can be generated by a 52 kg
person at a brisk walking pace using a PVDF (polyvinylidene fluoride) power harvesting device integrated in a
shoe. He continues to explain that Umeda (1996) attempted to harvest impact energy induced by a free falling
ball onto a plate integrated with PZT (lead zirconate titanate) wafer and it developed an electrical equivalent
model of transforming mechanical impact energy to electrical power. The findings of this experiment pioneered
energy storage using a bridge rectifier together with a capacitor. Energy harvesting by piezoelectric material
through the impact of rain drops has also been proposed and proven in principle (Guigon, 2008).
The duo from MIT whom behind the concept of ―Crowd Farming‖ carried out an experiment to demonstrate
their hypothesis by using block slippage against one another that performs as the power generator based on the
principle of a dynamo (Wright, 2007). They found out that a single human step is able to power two 60 Watt
light bulbs for about one flickering second; hence a crowd motion of 28 257 steps (per say) may generate
enough power to move a train for one second. They further supported their findings by lighting up a Light
Emitting Diode (LED) in a stool embedded with a generator every time a person sits on the stool.
Piezoelectricity in energy harvesting have also been proven by Kymsis (1998) by proving enough energy to
light up a bulb from a piezoelectric film implanted in a shoe sole.
According to Patel, et. al. (2010) again, two typical mostly or widely used piezoelectric materials were the
polymer membrane PVDF (polyvinylidene fluoride) and ceramic based PZT (lead zirconate titanate). The
conventional piezoelectric ceramic is considered rigid, heavy and are only produced in block form. On the other
hand, polymer based piezoelectric materials possess lower dielectric (an insulating material or a very poor
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4. 2012 International Conference on Innovation and Technology for Sustainable Built Environment (ICITSBE 2012)
16 – 17 April 2012, Perak, MALAYSIA. Ref No : GT –23.
conductor of electric current; (Britannica Encyclopedia, 2009)) and piezoelectric properties than ceramics; but
they are soft, flexible, low-cost and suitable for large area deployment. In addition, current development of PP
(polypropylene) polymer foam material demonstrates some superior properties in comparison to other two
common types of piezoelectric material. Due to the properties of the PP foam with a voided internal structure, it
is capable of storing large amount of electrical charges within these voids.
The developments of piezoelectric have advanced into a new dimension as nanotechnology is introduced. A
research carried out by Christian (2009) found that piezoelectric and nanotechnology can be combined to
explore the possibility of self-powered implantable microsystem; which basically is a self-powered micro
sensors implanted in a living body. The researchers carried out their study based on the findings of Kook
Chennault et. al. (2008); which indicated that the best harvesting strategy will always depend on the application,
the mechanical to electrical conversion through piezoelectric transducers; affirmatively the most promising
option. However, several challenges have been identified in applying nanowires in piezoelectric energy
harvesting potential.
In reference with the various research carried out on piezoelectric effect combined with the potential
development of nanotechnology, advancement in the field of inventing high efficient energy harvesting building
product or material may possibly be achieved. Vice versa, the disadvantages of piezoelectricity are also being
considered. Bergeron (2009) identifies weakness of piezoelectric effect as the high cost of installation and
maintenance. He continues to explain that the current available technology provides a small return on
investment (ROI) which therefore restricts its application in the industry. The major limitation is lacking in
affordable, general-purpose energy harvesting technology that could be applied in a variety of application areas
with high return on investment. The earlier mentioned experiment by DARPA was abandoned as the attempt
was viewed as impractical and has various negative impacts imposed on the user (Wright, 2007; Richard, 2006).
5.0 Research Methodology
5.1 Description of Methodology
This research shall adopt several research methods depending on its function and objectives. According to
Takim (2006), research method and methodology are interchangeably used, in fact their meaning are different.
Method is defined as the techniques used to do something; while methodology refers to the study of research
method. Since this paper is at its proposal stage, the research method shall be outlined, while the research
methodology will be explained in the next stage.
It is therefore this research shall be underpinned by:
i. Exploratory Research
ii. Descriptive Research
iii. Experimental Research
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5. 2012 International Conference on Innovation and Technology for Sustainable Built Environment (ICITSBE 2012)
16 – 17 April 2012, Perak, MALAYSIA. Ref No : GT –23.
5.2 Exploratory Research
Exploratory research is undertaken at the beginning of learning about a topic. Where little or no previous
knowledge exists, the researcher must engage in an open-ended search for answers and understanding. This
method may be loosely formulated that it rarely yields definitive answers. Exploratory research provides the
researcher with the insights and understanding that are needed into a topic to enable a more systematic study to
be carried out subsequently. Since exploratory research may lack any clear course at the outset, it may change
direction more than once. The basic categories of exploratory techniques that may be considered for this study
are:
• Secondary data analysis
Data previously collected and assembled for some project other than the project being studied
• Case Studies
A technique that intensively investigates one or a few situations similar to the researcher’s problem
situation.
5.3 Descriptive Research
Descriptive research can be used when the researcher has a clearer idea about the social phenomenon or
behaviour under investigation. Descriptive research provides details about a situation, setting or social
relationship. It is also designed to describe characteristics of a population or a phenomenon and determine the
answers to who, what, when, where and how questions.
5.4 Experimental Research
This type of research follows the principles found in natural sciences. Experiment manipulates sets of conditions
either in an artificial laboratory setting or in real life and then measure the differences in the way people respond
in those situations. Experiments are ideal for explanatory research because they can directly address cause and
effect relationship issues.
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6. 2012 International Conference on Innovation and Technology for Sustainable Built Environment (ICITSBE 2012)
16 – 17 April 2012, Perak, MALAYSIA. Ref No : GT –23.
6.0 Research Activities Flow Chart
Problem Statement Literature Review
PHASE 1
Exploratory Research
Secondary Data Case Studies
Problem Definition
PHASE 2
Selection of basic research method
Secondary Data Study Experimentation
Selection of Sample Design
Probability Non-probability
Data Collection & Analysis
Findings Interpretations
Report Writing & Presentation
PHASE 3
Development of Prototype
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7. 2012 International Conference on Innovation and Technology for Sustainable Built Environment (ICITSBE 2012)
16 – 17 April 2012, Perak, MALAYSIA. Ref No : GT –23.
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