Generating Electricity From Body Heat
Scientific innovations are not restricted to creating useful gadgets or machines. In fact, studies reveal that there are many scientific aspects that we can explore, particularly with regards to human body. One such recent example is the production of heat in the body which can create electricity: German scientists have identified a mechanism of converting body heat into electricity with the help of circuitry. This means that, in future, we will be able to operate our television and cellphones with nothing but the heat of our own body! Scientists are also hoping that this innovation will help reduce the world's energy problems.
An Amazing Fact
According to the scientists, in 15 per cent fat in a human body, it is possible to generate 11,000 watts of electricity per hour. In fact, different yielded energy levels are 81 watts from a sleeping person, 128 watts from a soldier standing at ease, 163 watts from a walking person, 407 watts from a briskly walking person, 1,048 watts from a long-distance runner, and 1,630 watts from a sprinter.
How does a human body generates heat?
The advancements in nanotechnology and material sciences are causing energy requirements to fall, but at the same time increasing its production and transfer. In order to use the movements of human body to generate electricity, scientists have developed a new class of devices that can function to manufacture energy from body movements, like muscles stretching. Also, the flow of the water is used to power future nanoscale components.
A nanometre is one-billionth of a metre; -- a human hair is roughly 100,000 -- generator which produces electrical current with the bending and relaxing of nanometre wires. These movements mimic the movements of body muscles.
These nanoscale components are called ‘nano-generators' or the thermoelectric generators, and made from semi-conductor elements which are less heavy than the conventional energy sources like batteries. The device is a prototype Zinc oxide nanowire, which extracts electrical energy simply from the change in temperature between a hot and a cold environment.
Since zinc oxide is non-toxic, the nano-generators can safely be implanted onto a human body. Inside the body, our cells produce mechanical energy by burning chemical energy that is generated through burning complex molecules of glucose into simpler ones. The nano-generators will utilise the mechanical energy and convert it into electrical energy for empowering devices inside the body.
The difference in temperature of the surrounding environment and the human body is very important in generating electricity through heat energy of the body. Since this variation in internal and external temperature is of few degrees, it would normally produce only around 200 millivolts and would not be sufficient enough to power electronic devices that normally require about 1-2 volts.
However, scientists have tried to combine a number of components in a completely new way for formulating circuits, which can function on 200 millivolts and will help in extracting heat energy from the body heat alone. Scientists also predict that in near future, temperature differences of just about 0.5 degrees will be sufficient enough to generate electricity. Some of the most capable mechanisms for inactively converting human body functions into electricity is piezoelectric effect.
The ‘Piezoelectric' substances are like ceramics which generate electricity from mechanical pull or press, and do not need any voltage to be applied on. This technique is used in ‘Heel strike' devices which generate electricity from walking. Likewise, the urine-based fuel cells are also used where one can use human excretory fluid into power.
Also, inertial energy scavenging technique is a unique type of energy gathering system. This is already being used in many Seiko watches powered by a weight system that swings with the movements of the wearer. Due to the small fraction of electrical production with these effects, there is not much hype about the electricity production of these device systems.
Benefits and uses
These nano-generators can be placed inside the shoe of the wearer where the heat is generated by the motion of feet, and then converted into electrical energy. The use of body energy in military is being aimed at for soldiers in battlefields using it as personal battery chargers, medical sensors, displays, gun sights, and range finders.
With the possibility of using body heat for generating electricity, scientists have found that this could be very useful in the field of medicine as well, particularly in hospitals where patients are observed round-the-clock. This includes checking pulse rate, heart rate, body temperature, blood pressure and breathing rate since it comes with a complex network of wires around the bedside, with each connection requiring its own electric supply.
Scientists can use hermo-generators for energising these complex wire systems for performing their work without creating a mess of electrical sources since they are capable of sensing the temperature variations in the body, and then collecting the heat into electrical energy.
In many fitness centres and dance clubs for example, the energy generated by the body movements of the customers was transformed into electricity and stored in a battery. This source of electricity is also being used to power the lights of the same gyms and night clubs. In fact, a Dutch environmental group is building a nightclub in Rotterdam that will have a dance floor converting vibrations from all the feet into electricity. One possible design for the floor involves piezoelectric crystals, which generate a small electric current when compressed.
Nasa’s plans on using the technology
Nasa is working to scoop up electrons which carry energy from the normal activities of the body like movement, bending and extending, compression, urine, and body heat. This is a unique plan, different from the other human-engineered schemes that take extra action, like spring or dynamo flashlights and radios which are wound-up by a particular handle, flashlights which are pressed by the user to produce charge or fly wheels which stock up energy from a cord that is dragged.
However, it is impossible to capture 100 per cent body energy under any circumstances. This is why body heat can only be converted in three per cent efficiency with current thermoelectric materials. The energy consumed by an individual is adequate for providing power to electronic devices if provided with a suitable method for changing a small portion of that energy into electricity. So it will not be wrong to say that very soon, we may possibly see children on bicycles where the pedalling will generates electricity to operate their headlights.
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