With the increase in the world population and the development of the economy, the level of electricity consumption is constantly increasing. On average, every 15 years, the amount of energy consumed in the world doubles. As demand increases, and with concerns about environmental impacts, the need for alternative renewable energy sources is becoming increasingly evident.
Perhaps the most interesting as a possible alternative are studies of the human body as a generator of various types of energy.
The relevance of this approach is due to a number of factors.
First, it is environmentally friendly. Only thermal energy or kinetic energy of movement produced by a person in everyday conditions is used.
Second, saving time and resources for storing and transferring energy for useful applications.
Power Plant Man
The first scientific study on the ability of living organisms to generate heat appeared in the 8th century. In 1791, the Italian scientist Luigi Galvani publishes the results of his 25-year work entitled Treatises on the Power of Electricity in Muscular Movement. The treatise confirmed that electricity is present in a living organism, and the nerves serve as a kind of "electric wires".
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In the XX century, scientists managed to prove that the human body is a "living power plant", which generates electricity as a result of continuous chemical reactions. And the separate science of electrophysiology was developed.
A kind of "energy capacity" of a person is also known. So, with one breath, one watt is generated, and with a calm step, you can power a 60-watt light bulb and even a phone. During rest, a person generates about 100 watts. And the largest energy production is achieved during sports - up to 2000 watts, for example, when sprinting.
By now, various technologies have been developed for the accumulation of heat from the human body and devices for recharging from a person, which can be conditionally divided into devices for collecting energy for a whole group of people and gadgets for individual use.
Passive heat
In Europe and North America, energy efficient homes are already being used, where the heat generated by people and household appliances is spent on heating the building itself. This is done due to thermal insulation, the absence of external ventilation in its structure and by installing a heat recovery device to transfer it to the heat supply system. Thus, residents can achieve savings on heating up to 90%.
In France, passive heating of a building allows 17 apartments to be supplied with "live" heat. For this, the social housing agency Paris Habitat uses the heat of the bodies of the passengers of the metro passing under the building. Warm air is transported through pipes to heat exchangers that heat the building itself.
A successful experiment was carried out in the main building of Stockholm Central Station, which is equipped with special heat exchangers. The devices collect the heat generated by the station visitors and transfer it to heating the water to heat the neighboring 13-storey building with an area of 28 thousand square meters. According to rough estimates, the system can save up to 25% of the energy used for heating a building.
Mass energy
Another promising technology is the collection of energy from the flow of people. Japan's East Japan Railway Company decided to use the visitor groups as a promising generator. Turnstiles with piezoelectric elements were placed at the station in the Tokyo subway, where hundreds of thousands of people pass every day. When approaching the turnstile, visitors step on the piezoelectric elements installed in the floor, and thus transmit energy from the pressure of their bodies.
In the Netherlands, generator doors have been installed at the entrance to the Natuurcafe La Port shopping center. This is where the push effect works. One such device produces up to 4600 kWh per year.
The busiest streams of people are found on the main streets of major cities in the world, where pedestrians, on average, take 50 thousand steps a day. British engineer Lawrence Camball-Cook figured out how to use this with paving slabs. Specially designed flexible material tiles flex slightly when pressed. So it is possible to use the kinetic energy of a person, which is converted into electricity. It is aimed at lighting streets, bus stops and shop windows. The innovative product has already been tested at the London Olympics in 2012, when 20 million joules of energy were obtained in two weeks.
Sports energy
Engineers working on methods of transforming the energy of movement of people, obviously, could not pass by physical education and sports. One of the first projects in this area was the Sport Art exercise bikes, which play the role of a transformer. They are equipped with an energy converter that generates a current of 120 volts and feeds it directly into the grid. For one training cycle on such a simulator, it is possible to obtain from 400 to 800 watts of energy. This will charge the coffee machine, a couple of TVs and laptops. The device even has a mobile app that calculates the amount of energy produced.
There are also more technological inventions, for example the Socceket soccer ball, which transforms the kinetic energy of an impact into electricity. At the moment of impact, the generated energy is transferred to a pendulum-like mechanism that drives a generator. The generator, in turn, produces and stores electricity. The ball has a power output of six watts, enough to power an LED table lamp or other small device.
Battery man
The dream of almost all users of pocket gadgets is to walk down the street and your smartphone is recharged without any additional batteries. This idea has not yet been fully realized, but scientists are gradually moving in this direction.
Korean scientists have developed a flexible generator measuring 10 by 10 centimeters, capable of recharging fitness bracelets. Energy is generated by the difference in temperature between the human body and the environment. The generator produces up to 40 milliwatts of energy.
A similar technology was presented by the Swiss smart watch manufacturer Sequent. The clock works by waving the hand while walking. And this is not a "self-feed" mechanism. Instead of a spring, a generator is installed there, which converts the vibrations of the load into electricity.
Researchers at Vanderbilt University have invented an element that allows electric currents to be produced by any human movement. The device is small in size and can be placed directly on clothing. Its novelty is that the energy of even the smallest movements is collected, that is, at frequencies up to 0.01 Hz, and it is generated continuously.
It is this technology that has the greatest potential to grow in order to recharge your smartphone on the go. But, in addition to charging gadgets, scientists see more extraordinary possibilities: for example, clothes with built-in stripes and a special liquid that will allow changing colors and patterns using a smartphone.
There are already universal developments. For example, a piezoelectric film that can be used to store energy when typing on a keyboard. Or when walking, if such a film is placed on clothes.