Imagine the amount of eggs which are consumed in a single day in the entire world, and the huge amountof eggshells thrown away every day. Technology has advanced to the point of using the membranes within the eggshells as one of the components of electricity generating devices. Many scientists in different parts of the world- India and Canada to be precise – have devised ingenious ways to use eggshell membrane for electricity generation. Here’s more about this unique development:
IIT Kharagpur’s new development – eggshell membrane for electricity generation
The brilliant students and professors at IIT Kharagpur have discovered a method for using eggshells for generating electricity. Using eggshells could potentially save these common items of waste from becoming just trash, and help them to be used in a much more meaningful manner. The Kharagpur researchers have built biocompatible nanogenerators of electricity. In other words, eggshells can be transformed into tiny electricity generating devices. The generators ‘make’ electricity from simple movements such as throat movements like drinking, gargling, swallowing, and coughing.
The eggshell membrane for electricity generation is effective as the nanogenerators are extremely sensitive to biomechanical pressure. This energy generation with eggshellscan be used to manufacture wearable medical devices, such as biomedical sensors.
The science behind
Many types of organic and inorganic substances are used to make tiny, nano devices which can harness the power of the human body, such as that generated by running, walking, and jogging.Most inorganic materials are toxic for the human body and non-biodegradable. But scientists at Kharagpur IIT have been successful in synthesizing nanogenerators using power of eggshellsi.e. the shell’s membrane which is a very fine, thin, porous, and protein rich layer between the albumin proteins of the egg and the calcified shell of the egg.
The energy generation with eggshellswas done with collaboration with scientists from Pohang University in South Korea. The eggshell membrane was isolated and coated with very thin copper tapes on both the sides, and golden electrodes were attached to them.The entire arrangement was then encapsulated in a silicon based polymer(organic).
The eggshell membrane for electricity generation was used to create nanogenerators. When the generators were subjected to some mechanical pressure – such as hand punching – the generators created a small amount of output voltage. Five of these generators were connected in a series connection to power approximately 90 light (green) emitting diodes. This implied that using eggshells for generating electricity has the potential to power calculators, wrist watches, and other portable, small electronic devices.
Eggshell membrane generators are efficient devices
It was found by the researchers at IIT Kharagpur that the eggshell devices could efficiently store electricity too, displaying their role as capacitors. These could therefore be fitted inside shoes to charge mobiles, as they could use the energy produced by a person running or walking. The devices did not lose their efficiency even after they were placed under several cycles of mechanical stress. The scientists said that these devices could be very useful to power many flexible and stretchable medical systems which monitor biological signals. They could thus be applied in the treatment of many diseases.
Alberta University research on energy generation with eggshell membrane
Professor Mitlin, at the Alberta University in Edmonton, Canada, has been trying to find a way to use eggshell membrane for electricity generation as well as egg whites into the base material for high performing super capacitors.
Suprcapacitors offer a higher rate of power density. They are also known for charging much faster than batteries – which have to be charged. The only drawback is that they store very little energy. According to Mitlin, eggshell membranes may help in ‘cracking’ that problem!
He is trying to figure out a device which has the power of supercapacitors but with much more energy density. If the energy density could be extended to even a mediocre level lithium ion battery, then the supercapacitors can be used in many applications, including consumer products and automotive sector.
How are eggshell supercapacitors made?
Electrochemical devices like supercapacitors store double layer charge on activated carbon electrodes. Mitlin and his colleague Zhi Li propose replacing the carbon electrodes with the eggshell membranes from industrial poultry farms. These chicken farms also supply egg yolks for use in the medicine and cosmetic industry. A huge number of eggshells and egg whites are thrown away as waste. These discarded shells and egg whites can be used in manufacturing supercapacitors.
How it works?
Li and Mitlin heat the eggshells to 800 degrees Celcius. Then they activate the organic material by heating it up to 300 degrees Celcius for about two hours. The membranes then transform into a material resembling construction paper. The membranes retain their structure, and provide a large enough surface area which can hold electrical charge, thus proving that eggshell membrane for electricity generation is a viable option.
The high nitrogen content also leads to a very high capacitance, though why that happens is stillsomething that cannot be explained by scientists. The capacitance of about 300 farads per gm in eggshell membrane supercapacitors is 100 times higher than those made using activated carbon. The material is 97% efficient even after 10,000 charge and discharge cycles in acidic electrolyte.
Eggshell membrane for electricity generationin this method can be quite useful. But Mitlin and his co-researcher went a step further. They used the carbon from egg whites to make a porous substance which was used as anode in lithium ion battery. The capacity of 1800 milliamps was displayed by the egg white anodes, which is highest reversible capacity of carbon ever reported.
Commercializing the tech
In order to bring their invention to the people, Mitlin as well as his colleagues have started a company called Altacap. They’re trying to find out the best possible industry which would suit their discovery. Though the most obvious choice is the automotive industry. This is because the higher density of supercapacitors could shorten the time significantly to recharge electric vehicles.
Lithium batteries are one of the worst pollutants. They are non-biodegradable and emit greenhouse gases. Replacing them with unique nanogenerators using eggshell membrane for electricity generation will be a big win for the planet.