Generation of Electricity from Human Footsteps: Taking a closer look

Greetings Steemians. It’s good to have you here again.

Electricity is very vital in human survival and in fact it has been described as one of the most important inventions achieved through science. However, there are dangers such as global pollution inherent in the use of the traditional sources for electricity. As a result of this, scientists have turned to alternative energy sources such as solar energy, wind energy, biomass energy, geothermal energy, hydropower etc. as an answer to the problems associated with the use of fossil fuels. Energy generated from foot-steps is another green energy that has been proposed to be used mostly in crowded environment. Let your imagination take a trip with me as I discuss this technology. The truth is stranger than fiction

_{Pxhere Creative Commons CCO}

DEFINITIONS

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I wouldn’t want to bore you with theories but it is essential that we look through some terms as they are key to the main discussion

• Piezoelectric effect: This is simply the ability of certain solid materials such as ceramics (aluminium nitride, zinc oxide, lithium niobate, gallium arsenide etc.), biological matter and quartz crystals to generate electric charge by the application of mechanical force on them. This electric charge is regarded as piezoelectricity. The process is reversible such that mechanical strain is also generated when electricity is applied. The word “Piezo” is a Greek work that stands for squeezing or pressing.

• Piezoelectric sensors: these are simple elements that are based on piezoelectric effect and measure changes in pressure, mechanical strain, acceleration, force, vibration by converting them to electricity

• Electromagnetic induction: is simply the creation of voltage in an electric conductor when it is placed in a varying magnetic field. It can be demonstrated in two ways, viz., when a conductor is moving in a static magnetic field and when it is placed in a varying magnetic field.

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THE IDEA

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The idea is quite simple and has been demonstrated by many researchers and companies using various techniques. Think of it as the energy derived from human while walking or running. The idea is to harness the kinetic energy produced by human movement and convert it to electricity. You could also think of it as energy generated by converting the force transferred to the ground by footsteps as a result of the weight of human body into electricity since kinetic energy generates force as shown below.

K.E=1/2 mv²
F=m.a
_{And by manipulation of parameters} K.E=1/2 F.at²
Where K.E is kinetic energy, F= Force, m= mass, v=velocity, a = acceleration and t = time
This conversion is achieved through electromagnetic induction, piezoelectric effect and by using the kinetic energy generated to drive a simple electric generator

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EXISTING SYSTEMS

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This article will be incomplete without mentioning the amazing works that has been done in the area of generating electricity from the human movement.

• Electromagnetic Foot Step Power Generation: This is based on electromagnetic induction principle. It involves the conversion of pressure into electrical energy. The researchers who demonstrated this made use of metal plate, copper coils, bar magnets, connecting wires and 12v deep cycle battery to store the voltage generated. The metal plate is the surface upon which force will be exerted. A compression spring attached to a bar magnet is placed under the metal plate. When force is exerted on the plate, the spring gets compressed and the magnet attached to it hit the copper coils at the bottom plate and in the process voltage is induced in the coil. The generated voltage is then stored in a battery where it can be further rectified to A.C.
  One of the challenges of this arrangement is that it is not compact enough to be installed in crowded environment.

• Generation through piezoelectric effect: This is based on the use of piezoelectric tiles and electromagnetic induction. A major leap in this area was achieved nine years ago by a certain company called “Pavegen”. The company prides itself as the only company to have productized this concept by installing the tiles at different dance floors, shopping centers and London Olympics stadium for low-wattage applications such as lighting, advertising and displays. The tiles used by the company are developed from recycled rubber materials and power is generated when the tile is pressed. Pavegen founder Laurence Kemball-Cook says

Each pedestrian generates an average of 5 watts per footstep at 12-48 volts DC, enough to run an LED street lamp for 30 seconds.

I was amazed when I saw the videos of these demonstrations on Youtube. You can also see one of the videos below.

_{[Credit: Pavegen Powering Education - Published by Pavegen on YouTube- Sep 18, 2013]}

• Power hump: This arrangement is a bit different. Here, electricity is generated from speed breakers. The force needed in this case is generated by moving vehicles. Rack and pinion mechanism is used to convert the kinetic energy of moving vehicles into mechanical energy.

A pinion is a small spur (circular) gear while the rack is a linear gear. This mechanism is commonly used in steering system. The rack and pinion mechanism is used to convert rotational motion into translational motion and vice versa.

In this case, the rack and pinion gears are hidden under the speed breaker to transform translational motion into rotary motion which is then used to drive an electric dynamo to generate electricity. The rack is pushed down whenever a vehicle steps on the speed breaker. The rack in turn rotates the pinion in one direction. A sprocket drive and chain is used to amplify the rotational motion and a flywheel is used to regulate the motion by storing the kinetic energy which is then used to drive the electric dynamo to produce electricity.

A major disadvantage of this arrangement is that some components may get destroyed when the vehicle is too heavy.
I’m sure you must be wondering about the magnitude of the voltage generated using this technique. The researchers who demonstrated this recorded that the voltage varied directly with the speed and weight of the moving vehicle. For example, a 400kg load using this technique generated about 273.24 watts.

As stated earlier, you would have noticed that the idea in all these systems is to convert kinetic energy to electrical energy. This has been achieved in turbines but the goal is to eliminate the pollution associated during this conversion and that why human footsteps were considered. You will agree with me that anything/animal that can generate kinetic energy without pollution can also do the job.

APPLICATIONS

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This concept can be used in crowded environments such as churches, mosques, clubs, cinema theaters, airports, universities, stadiums etc. For instance, record has it that over a million people gather in Mecca every year for the Islamic pilgrimage and in most cases, the people march from one place to another when executing their worship activities. Imagine the amount of energy that would be generated from their footsteps. Obviously, it will be massive.

_{Picture by Aiman titi - wikicommon CC BY- SA 3.0
The way to Jamarat Bridge}

LIMITATIONS

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• Low energy: The energy derived from this method is very low and cannot be used to power heavy devices and machines let alone be supplied from one location to another. It can only be used for low wattage applications such as street lighting, charging, displays etc. For instance, some researchers after carrying out a study on Pavegen system realized that 54,267 footsteps on the tile produced an output of 217,028 watt-seconds which is merely 0.06kWh and have criticized the system as

tiny, pointless amounts of energy

• Instability of supply: The power generated through this means is intermittent as it is dependent on footfalls which obviously occur at intervals. Also, the power generating capacity of this technology highly depends on the population of passing persons. The system is limited solely to footfalls in crowded environment before any substantial amount of energy can be generated.
• Cost: The initial cost of production and installation of all these arrangements is very high. For example, a Pavegen tile is about $75 - $160 per square foot. Now imagine what the total cost would be if it were installed in large auditoriums and walkways.

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CONCLUSION

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In this article, we have seen kinetic energy as the basis upon which the generation of power from human footsteps thrives. We have also seen the various systems that have been demonstrated in this area and how that the Pavegen tiles is the best shot so far.

The generation of electricity from footstep is eco-friendly, requires no fuel and utilizes energy that would have wasted from human locomotion. It is a fantastic development and a seeming uncharted territory in non- conventional energy sources but its present limitations seem to outweigh the benefits. However, one cannot completely overrule the possibility of a better system in the years to come

Hopefully this article has provided you with the necessary information to understand and catch up with the happenings in power generation through human locomotion. Be sure to leave your comments below. Thank you for reading. See you next time.

REFERENCES

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_{Pavegen tiles harvest energy from footsteps
Electromagnetic induction
Piezoelecticity
The floor tiles that use foot power to light up cities
Power generation from speed breakers
Alla, C.S., Murali, B.K & Jogi, R.T. (2014). Electromagnetic Foot Step Power Generation. International Journal of Scientific and Research Publications. 4(6):1-5
Vinod, K. & Nagabhushan, K. (2014). Foot step power generation system for rural energy application to run an automated toll gate system. International Journal of Computer Science and Mobile Computing. 3(16): 414-420}

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