Bangladesh is a country which occupies an area of 1, 47,000 square kilometre of land with 85 per cent of it being rural.In these areas, there are places where electricity is in paucity and/or is unstable. However, the usage of mobile phones is a common scenario despite the scarcity of electricity in those areas.
Charging cell phones is quite a hassle in the areas where electricity is either unstable or unavailable.
A design team of the Department of Electrical and Computer Engineering of North South University, Dhaka has designed a low-cost device thatcan charge up mobile phones using the wasted heat energy from regular household cooking.
The main concept behind this design is the "Thermoelectric effect." It involves the direct conversion of heat energy to electrical potential. The device use sa Thermoelectric Generator (TEG) module to do this job.
The TEG uses the principle of Seebeck Effect, which states that if two different metals are held at different temperatures (also known as a Thermocouple), a voltage will be developed.
The hot side of the TEG absorbs the heat and transfers the heat to the cold side which has a heat sink attached to it so that the heat is dispersed.As a result there is a temperature difference, which means there will be a voltage produced in the output. However, the voltage produced is almost negligible and thus requires a boost.So, the team has also designed a DC-DC voltage step-up regulator that amplifies the small voltage output of the TEG to at least 5 Volts (minimum voltage required to charge up a cell phone).
The cost of this system is only around 5000 Taka, while comparable systems available at the overseas markets cost much higher. For example, a system named Biolitestove available in developed countries costs about US$129.95 (about 10,150 Taka) and another similar system named Power Pot V costs US$149 (about 11,635 Taka).
Even though the designed system is fully functional electrically, its mechanism is something that is still being worked on. For now, the heat is passed on to the TEG using aluminium plate as a medium. So the time required for the TEG to receive heat and develop the voltage is longer.
Direct exposure of the TEG to heat will result in faster conversion. This is something that the team is currently working on. The idea is to make it even more light weight and portable and most importantly, more efficient; therefore making it much easier for people to use it.
The principle of the designed system can also be used in industries, where a large amount of heat is usually wasted.
Besides cooking, the team is at the moment also working on how to make the device develop voltage just by latching the system to any heated factory machine. The thermoelectric module will be exposed to the surface of the machine where the hot side of the module will be absorb the heat and result in a voltage. This will ameliorate the use of the device to its full potential.
The generated electrical energy can also be made portable by storing it in Super-Capacitors. The Super Capacitor can be used as a source later when the system is not under the exposure of heat and can still charge up devices.
In addition, a LCD temperature monitor is being added to the system, powered by a microcontroller which has a sensor to show how much temperature is being converted to voltage. This system involves the renewal and recycling of wasted heat into additional electric power.
The designed system can also be used in third-world countries like many in Africa where electricity is a challenge. Using this technology, people in those countries can cook their food and charge their mobile phones and electronic gadgets at the same time. This is a growing technology and there are high scopes for the designed system once it is in the manufacturing state.
The four member design team includes senior level students Chowdhury Erfan Shourov, Abdullah Al Mahmood, Noor E Alam Siddique, and the team supervisor Dr. Hasan Uz Zaman (Associate Professor) of the Department of Electrical and Computer Engineering of North South University. It was a Capstone Design project (also known as Senior Design), which is a requirement for an undergraduate degree in engineering in universities following US style curriculum.
Md Faisal Hossain is a Electrical and Electronic Engineering(EEE) graduate at North South University