Earth-Friendly!

 

 

 

 

 

 

 

 

An Introduction

 

In our everyday life, we are constantly walking about to get from one place to another. Be it from home to the nearest mall, to get to the toilet, from school to the bus stop, or simply for a desire to exercise, we are constantly on the move. Walking is the most basic form of transport since the dawn of the anatomically modern human species approximately 200,000 years ago. It is something all humans learn to do since we are toddlers.

 

Our group realised that quite a sizeable amount of kinetic energy is created from walking. We thought that it would be highly beneficial if we could convert some of this kinetic energy from walking into chemical potential energy for other usage. This is to fully tap into the kinetic energy so as to minimize energy wastage. If people have access to a device that could convert kinetic energy from walking into chemical potential energy, it would be a solution to energy wastage. Solving energy wastage is pertinent in today’s world, with a large proportion of energy generated by fossil fuels and natural gas, which are non-renewable sources of energy, being depleted drastically. With the rapidly increasing world population, demand for energy has also risen, whereas supply has not matched up, pushing up prices for electricity, which comes from electrical energy mainly generated through those two resources. Our group felt a strong need to overcome this issue, and we decided to solve this issue in the best way we could, by coming up with a device that could convert kinetic energy from walking into chemical potential energy, to maximise the benefits from walking. At the same time, this chemical potential energy stored in batteries could be used to charge electronic devices, minimising energy consumption in the form of electricity in the long run.

 

Also, our group realised that in this increasingly wired and globalised world, people lead increasingly inactive lifestyles, spending more time in small office spaces and in front of electronic screens. People who use our device from being incentivised to save on their electrical bills and save the planet are made to exercise, subconsciously. Exercising could lead to greater physical and mental health, resulting in healthier and happier people, increasing their productivity in the workforce and reducing healthcare spending globally, allowing more expenditure to be channelled into research and development in other areas which could benefit humankind more efficiently.

 

Climate change around the world has seen an increased need to engage in energy sustainability, due to its disastrous effects on infrastructure and lives. Employing more sustainable energy could immensely reduce the rate of climate change. Thus, such research and development would be highly appropriate when used to work on energy sustainability. Ultimately, the device that our group has come up with aims to encourage and achieve energy sustainability in the long run.

 

 

 

 

Project Description

 

Our group’s goal is to convert kinetic energy produced from walking or running into electrical energy using a device placed in our shoes, called INsoul which can be used to charge mobile phones. Approximately 6 billion of the 7 billion people in the world have at least a mobile phone each. Surprisingly, this number is more than that of the number of people having access to toilets. Therefore, we thought that it would benefit users a lot if this power created could be used to charge mobile phones.

 

The mechanism behind INsoul would be elaborated further in a later section of the report.  Should the product be a success, we hope to make it accessible to all as well as hope for continued research into improving INsoul.

 

When we walk, our feet apply pressure on our heels, which can be used to move two wire coils around a magnet, resulting in a changing magnetic flux around the coils. According to Faraday’s Law of induction and Lenz’s law, an electromotive force will be induced and current will flow through the coils, generating electrical energy.

 

The electrical energy can be stored in rechargeable batteries as chemical potential energy for future usage. A person walks about 10 000 steps every day. Each step generates ~0.0003V of electricity per step. The battery voltage's is 3.6V. Thus, number of steps required to supply the battery with 3.6V is 12 000 steps. The current would be approximately 2 amperes per hour, thus power produced is 3.6V*2A/(60*60)=2.4/(60*60)=~0.002W, from P=VI.

 

A 10km runner who runs at twice the pace of a stroller every day, would take about 40 000 steps per day. This means this runner can generate at least 40 000/12 000 * 0.002=~0.007W of power a day. Assuming the runner takes 2 steps every second, and runs for an hour every day, the runner generates 0.007*2*60*60=~50W of power per day from his daily 10km run. A typical mobile phone uses 0.4W per second on average. Thus, the runner's phone can be charged for more than 50/0.007 seconds, which is more than 2 minutes of use every day.

 

Assuming the runner does not use his phone a lot and uses a non-smart phone, which consumes relatively little power and has main functions of simply calling and texting, the phone can be powered solely through INsoul, without the need to plug into any electrical sockets for charging and still be used. These values are based on estimates, which can be improved on when building our prototype.

 

With INsoul, users simply require a portable charger that can fit 4 AA-sized rechargeable batteries (2 from each shoe) with a USB Port for fitting USB cables, and a USB cable for users to plug into their respective phone models, depending on the type of phone used. Their phones can be charged anytime, anywhere, as long as they have INsoul with them.

 

Our group has noticed that simply having the portable chargers becomes impractical when these chargers have no more chemical potential energy left stored in the batteries they contain and there are no available power plugs in the vicinity. This issue could be solved with INsoul, as it is a fact that almost every human adult can walk, and the power for INsoul is essentially generated through walking. Shoes are required, which almost everyone has. Walking can result in storage of chemical potential energy in the rechargeable batteries placed in the shoes by the workings of INsoul. These batteries can be conveniently removed from the shoes, and then inserted into portable chargers for charging mobile phones repeatedly, without having to incur any extra electricity bills.

 

 

 

 

 

 

 

 

 

 

 

Prototype Proposal - Theory and Description of Prototype

 

The structures listed below are contained in INsoul. INsoul is basically made using silicone and the insoles of sports shoes. It will consist of an insole from a sports shoe as its base with the electricity generating device on the base. The whole structure will then be covered by another silicone layer. Above this cover is the insole of the user’s shoes. The entire silicone's interior is coated with a layer of steel. 

There will be 4 springs on the base of the insole, encircling the magnet, which will be fixed at the base of the shoe. Two coils will be attached to the 4 springs, with each spring supporting a corner of each coil. Two coils are used to compensate for the lack of vertical height, to increase the number of coils horizontally to increase energy generated. The coils will be linked to two protected AA rechargeable batteries, on both the right and left sides of the shoes, with wires, to create a closed circuit. The batteries will store the energy generated for further use.

The protected Lithium-ion rechargeable batteries can be taken out easily from the top of INsoul,  as the top silicone piece is separate from the other parts of INsoul. The silicone coating of INsoul will waterproof the whole INsoul, and the coat of steel on the interior of INsoul, coated via electroplating, will prevent any attraction with other nearby magnetic objects. After removal from INsoul, the rechargeable batteries can then be placed into a portable mobile phone charger (provided together with INsoul), which is able to connect to any USB cable to charge phones.

Whenever the user walks, force the user exerts pushes the coils downwards, causing the coils to surround the magnet. The springs will revert back to its original length after compression when the heel is in the air. Thus, the magnet will be in and out of the coils repeatedly as the coils moves up and down when the person walks. This leads to a continuous change in magnetic flux. The continuous change in magnetic flux then result in a current being induced continuously. Hence, whenever the person walks, electrical energy will be generated continuously and this energy will be stored in the batteries.

Each coil is made up of copper wires (~ 0.5 - 1mm) and has 20 turns tightly wound to ensure the greatest amount of current generated in the limited space. The 4 springs will be about 10mm in length, and have a diameter of 10mm so as to support the coils properly. The coils will be about 20mm in height; with an inner diameter of about 12mm, and outer diameter of 15mm. The magnet will be approximately 10 mm with a diameter of 9mm. This leaves about 3mm of buffer space between the top insole and the coils. This buffer space ensures that the coils are not surrounding the magnet at all when the heel is in the air. The magnet used will be Samarium Cobalt magnet in a rectangular bar shape as it has good magnetic strength, good corrosion resistance and good thermal stability. Using any other magnet stronger in magnetic strength may pose as a hazard to the user of INsoul, by the greater ability to attract surrounding objects made of magnetic material. The small size is compensated for by the strong magnetic strength of the magnet.

1st Runner-Ups in TUWAE Young Engineers Competition of World Engineers Summit 2013!

Catch a video of us making INsoul!