ADIRA NURANI VAIDYANTHAN1, VIJAYA ILANGO 2*
1, 2Birla Institute of Technology & Science, Bits Pilani, Dubai
Corresponding author: [email protected]
Abstract: The demand for power is
increasing day by day. Efficient, inexpensive and clean
alternatives need to
be devised. Human Power is one
the most efficient alternative
source of energy. To fulfill the demands of the growing population
effective and efficient technique to convert mechanical energy to electrical
energy needs to be devised. This paper discusses the proposal of a new model which
cost-effective, less complicated and
eco-friendly as compared to the existing models. The process describes the conversion
of human footsteps to electrical energy by converting linear motion to rotational motion and further
converting mechanical energy
to electrical energy. The electrical power
generated can be stored in batteries. This stored energy can be used for a wide
of purposes. Every
Keywords: Mechanical energy, Electrical energy, Linear motion, Rotational motion, Piston,
The human body contains tremendous quantities of energy. In fact, the average adult has as much energy stored in fat as a one-ton battery. That energy is used for our everyday activities, but if those actions could in turn run the electronic devices we rely then we do need an external source of power. In the past, devices that turned human kinetic energy
into electricity, such as hand-cranked radios, computers and flashlights, involved a person’s full participation. But a growing field is tapping into our energy without even us noticing it. It is a biological
process that turns fat into energy which is beyond currently available technology.
Scientists have an idea that one way to stem climate change might be to harvest tiny amounts of energy in the form of the body’s heat, movement, metabolism and vibrations. In one form
of the technology, experts are turning to piezoelectricity, which means “electricity
from pressure”. In
a piezo-electric material, small amounts of power are
it is pushed out of shape. As an extraordinary example of what’s now possible with
materials, the heart itself could
be used to
artificial pacemaker. But as Dr Amin
Karami at the University of Michigan
says, a pacemaker that harvests the energy of the
heartbeat itself might operate for a lifetime. In a recent address to the American Heart Association
in Los Angeles, he pointed out that a sliver of a piezoelectric ceramic one
hundredth of an inch thick, powered by vibrations in the chest cavity, can generate almost 10 times the power required to operate a pacemaker. The technology can be used on the outside
of the body as well. Nanotechnology
researchers are developing the perfect complement to the power tie: a “power shirt” woven
from pairs of fibres coated with tiny strips of zinc oxide
gold. As you move, the fibres rub against each other to produce a current. Prof Zhong Lin
Wang, at the
of Technology, says that “we could provide
a flexible, foldable
wearable power source that, for example,
would allow people to generate their own
electrical current while walking. 1
Basal metabolic rate
Well – trained cyclist (1 hour)
Modern racing cyclists
Manual laborer (8-hour work shift)
Table No. 1:
Power Produced by various sources
However potential yield of human electric power is decreased by
generator device, since all real
generators incur considerable losses during the energy
conversion process 2. While attempts have been made to fit electric generators to exercise equipment, the energy collected is of low value compared to the cost of the conversion
The latest techniques which were developed to produce energy from human power include
the following: –
1. Automatic Watches: –
Some wristwatches are powered by kinetic energy (called automatic watches), in this case movement of the arm is used. The arm movement causes winding of its
mainspring. A newer
by Seiko (“Kinetic”)
of a magnet in
electromagnetic generator instead to power the quartz movement. The motion provides a
rate of change of flux, which results in some induced emf on the coils. The concept is
simply related to Faraday’s Law.3
Fig 1: Seiko Kinetic Drive
Fig 2: Faraday’s Law
Piezoelectric Fibers: –
crystals or fibers generate a small voltage whenever they are mechanically deformed. Vibration from engines can stimulate piezoelectric materials, as can the heel
shoe, or the pushing of a button. 3
Fig 3: Piezoelectric disks generate voltage when deformed
3. Power Keys: –
from keys pressed
during use of a
portable electronic device or remote
controller, using magnet and coil or piezoelectric energy converters, may be used to help power the
Fig 4: Remote control
4. Human electric hybrid vehicle: –
It is a hybrid vehicle, or more specifically a hybrid human powered vehicle, whose drive train consists
of a human
motor/generator (and one or
electricity-storage device(s) such as a battery(ies) or ultra-capacitor(s)). Some vehicles can operate off both human power and be plugged in to operate on battery power. 3
Fig 5: Human electric hybrid vehicle
The main aim of the model is to generate electric current while walking. A large amount of
can be generated through this model when arranged on a large scale in places where
public pedestrian movements are enormous.14 This setup can be located on foot-steps
or on staircase of any metro or airports, shopping malls, supermarkets where pedestrian movement is
the maximum. This
idea is based
on pressure and Electromagnetic Induction. It involves the conversion of mechanical energy to electrical energy.15 Air is used to transmit the pressure produced on one end to
other. Linear motion
gets converted to rotational motion. This method is cost effective and can be widely used from charging a battery to powering a room. Compared to the other methods mentioned above this
proposal is simplified
and does not involve the use of complex sensors or equipments. It is efficient and can act as a source for a wide range of demands.4
• On an average for each step taken =
12V * 0.5A = 6Watt.
• 6Watt is produced assuming constant voltage of 12V.
The laws involved are: –
1. Pascal’s law on pressure: -Pascal’s law on pressure states that a pressure change occurring anywhere in
out the fluid such that the same changes occur everywhere.
Fig 6: Pascal’s law representation
2. Electromagnetic induction: -Electromagnetic Induction is the production of an electromotive force (i.e. Voltage) across an electrical conductor in a changing magnetic – field.
Fig 7: Electromagnetic Induction
PROPOSED SCHEMATIC DIAGRAM OF
Fig 8: Detailed sketch
• Wooden box – acts as a step and a case for the air bag
• Sphygmomanometer – Air bag
• Squeezable bulb – it is connected to one of the ends of the sphygmomanometer and is
used to pump in air into the air bag
• tube wires – is used to pass the air released without any loss
• Syringe 60ml – it acts as a piston
• Gear arrangement – it is where the conversion of the linear motion to rotational motion
• Generator – is where the mechanical energy gets converted to electrical
• Battery – is to store the electrical
DESCRIPTION OF THE COMPONENTS
Fig 9: Human Power Generation Model
1. Wooden Box – The wooden box acts as a case for the air bag. It is used as a step on which
an external pressure is exerted. The dimensions of the wooden box are
length = 50cm,
breadth = 40cm, height = 6cm. The box is made of wood so that it is sturdy
enough to withstand even if a strong pressure is exerted.
2. Sphygmomanometer –
An instrument for measuring blood pressure, typically consisting of
inflatable rubber cuff which is applied to the arm and connected to a column of mercury next to a graduated scale, enabling the determination of systolic and diastolic blood
pressure by increasing and gradually releasing the pressure in the cuff. But here, we use it as an air bag which transports the pressure exerted on one end to the other. 7
Bulb – It is part of the sphygmomanometer which is used to pump in air into
air bag. It has a knob to adjust the flow rate entering the air bag and can be closed to confine the air within the bag.
wires – These wires
are inexpensive and prevent the loss
of pressure while transporting them from one end to the other.
5. Syringe –
syringe is used as a piston. It is attached to a small wooden board and the end of the syringe is tied to the clamps using elastic bands. This is done to get an upward
and downward motion like in the piston. This is the linear motion. Here, Pascal’s law on pressure is applied. The syringe used here has 60ml capacity.
6. Gear arrangement – The gear arrangement is where the linear motion is converted to
rotational motion. The arrangement consists of 2 gears. First one slightly
larger than the second one.
7. Generator – Here the input is rotational motion and the output comes out as electrical
energy. We apply the Electromagnetic Induction principle here.
8. Battery – The electrical energy which comes out as output from the generator can be stored
in the battery. This stored electrical energy
can be further used as an input for any
WORKING OF THE MODEL
The sketch was made based on the aim of producing energy for each step taken by an individual, not even a single step is wasted here.
• As a pressure on the box is applied the air bag releases air due to the force experienced.
• Both ends of
(which is placed inside the wooden box), is
connected. One end is connected to
squeezable bulb and
the other to the wire. This air is transmitted through tube wires to a syringe which acts as a piston (here Pascal’s Law
Pressure is applied).
• The motion of the piston is controlled by elastic bands which helps it to produce an up and
down motion for every step.
• This linear motion is converted to rotational motion using the gear arrangement. The piston and the first gear is attached using a strong copper rod.
• The gears are fitted with the help of shafts and the hole on the metal
plate is enlarged for
movement (through which the shaft passes). The gears are placed at a height to ensure free movement without intervention with the flat metal plate.
• The shaft of the second gear is made movable and is attached to the rotor shaft so that as the second gear rotates, the rotor shaft also rotates along with it. The generator is clamped
to the metal
plate; to avoid the rotation of the generator with the shaft.
• This rotational motion is given as an input to the generator which produces electrical
energy (here Electromagnetic Induction is applied).
• The mechanical energy to electrical energy conversion happens within the generator. This generator can also act as a motor.
• This electrical energy is stored in batteries. The wires are soldered on the generator and
then it is connected to the battery.
– These gears are very light-weight and their cut teeth is perfectly defined. They rotate freely
without any friction when arranged on a particular height with the help of shafts.
3D PRINTING – An alternative method to design the required design of gear online and print it. Fiber is used here instead of plastic.
• A Software called Tinkercad was used to design the gear models on a 3-dimensional work
• A .stl code was generated which was converted to a .gcode and printed using a 3D printer.
• Time taken – It took 4 hours to print a 2inch gear.
• The gear arrangement is in descending order of size.
• As the first gear experiences a 0.5 rotation the next gear will rotate more than 1 complete
rotation; refer Fig 11.
• The gear models can be downloaded and can be edited using this online software.
• The unit of measurement used is mm in the software.
• The gears need to be arranged in such a way that all
them rotate freely without friction or without getting stuck; refer Fig 10.
• Dimensions of gears are: –
Gear 1: h1 = 20mm, d1 = 137.36mm
Gear 2: h2 = 30mm, d2 = 100mm
Fig 10: Gear arrangement
Fig 11: Gear rotation
This setup can be placed in locations where a large population is always present. It can be
placed in malls, airports, schools, colleges, metro stations, fitness facilities etc. 5 Every step counts. A large amount of energy will get stored in the battery for every step. Voltage = 12V,
for 1 step = 12V *0.5A = 6Watt. This setup’s efficiency can be increased with the addition of an additional generator or an extra gear to the gear arrangement. 6 The additional
will increase the input to the generator so more electricity is produced. The gear will increase the rpm so more output is obtained. This experiment can be kept under the entrance carpets. If the setup is placed on a stair more pressure will be applied as the pressure exerted by a human
while walking and while
climbing stairs is different. Hence, if placed on a stair more pressure is exerted. The wooden box is sturdy enough to support a powerful external pressure exerted on
it. The height of the box is 6cm, a small plank is placed to raise the height as the air bag should experience the pressure exerted for the air to flow. A multimeter can be used to
analyze the current obtained for a
specific time period. Analyzing the data
produced for unit time with the population; refer Fig 12.
Fig 12: Population vs electricity
This setup was assembled and kept in the entrance of a flat with approximately 72 households
for 2 hours. 7 The power collected was approximately 2V which is the power requirement for
a AAA battery. This AAA battery can be used for remote controls. 8
Setup assembled for testing
·It is cost effective compared to the latest and complicated technologies where piezoelectric
sensors are used to detect and collect the electrical energy. 9
source of energy is required other than the human power.
It ranges from charging your phone to supplying electricity to a household.
·The entire setup costed around 150aed; which is cost efficient compared to the other techniques mentioned. 10
·This setup can be easily implemented anywhere to obtain electricity and can also be
supplied as an input source in that environment.
Easy to transport and easy to understand.
· The pressure in the air bag must be maintained to ensure easy flow of air throughout.
Ensure no leakage in the tube wires to avoid the loss of pressure. 11
Piston and Gear arrangement must be attached properly on a rigid surface.
The Piston must be lubricated with oil to ensure for easy movement.
This model can be used for a large-scale purpose,
By increasing the size of the syringe more air can be pumped in.
The rpm can be increased by adding more gears of smaller diameter.
Bearings can be used for easy movement of the copper rod and hence increasing the
rpm giving more output.
to thank the Director
Pilani Dubai Campus
encouragement and support in facilitating the research and other experimental activities.
1. Cross, R. & Spencer,R. 2008. Sustainable gardens. CSIRO Publishing, Collingwood,
Melbourne. ISBN 978-0-643-09422-2.
2. Eugene A. Avallone et. Al,(ed),Marks’ Standard Handbook for Mechanical Engineers
11th Edition, Mc-Graw Hill, New York 2007 ISBN
0-07-142867-4 page 4-9
3. Tom Gibson, Turning sweat into watts, IEEE Spectrum Volume 48 Number 7 July
2011, pp. 50-55.
4. Modelling human power and endurance, January 1990, Volume 28, Issue 1, pp.49-64.
5. Human Power Generation in Fitness Facilities, January 2010, Conference Paper.
6. Human power amplifier technology at the University of California, Berkeley, Kazerooni
H. Rob Auton Syst. 1996.
7. Human power utilization, Volume No. 04, Issue No. 03, Year 2017, Paper No. 1837.
8. Maximizing Human Power Output by Suitable Selection of Motion Cycle and Load,
Published on June 1, 1970.
9. Abbott, B. C., Bigland, Brenda, Ritchie, J. M. The physiological cost of negative work.
Journal of Physiology, 1952, 117, 380.
10. Benedict, F. G.,
study with special reference to the efficiency of the human body as a machine. Washington, D.C.: Carnegie Institute Publication 187, 1913.
11. Harrison, J. Y. The effect of various motion cycles on human power output. Human
Factors, 1963, 5, 453.
12. Dickinson, Sylvia. The efficiency of bicycle-pedaling as affected by speed and load.
Physiology, 1929, 67, 242.
13. Henderson, Y., Haggard, H. W. The maximum of human power and its fuel. American
Journal of Physiology, 1925, 72, 264.
14. Henry, F. M., de Moor, Janice. Metabolic efficiency of exercise in relation to work load
at constant speed. Journal of Applied Physiology, 1950, 2, 481.
15. Krendel, E. S. Man-generated power. Mechanical Engineering, 1960, 82, 36.