Power does not always come out of the socket. Energy harvesting, which means roughly energy-harvesting is the generation of electrical energy in small quantities from the environment of electronic devices to operate so that these in turn. Sounds complicated – it is not.
Energy is practically everywhere. Already by tiny differences in ambient temperature electrical current can be generated. By using special instruments, it is possible to capture this stream and used. The energy sources used in addition to the ambient temperature, air pressure fluctuations, vibrations, heat or air currents. Even light, radio waves or existing biological processes can be used to generate electricity.
The method is already known from the use of special sensors in flexible Paving slabs or dance floors. If they convert energy into electrical energy, enabling the operation of LED lighting systems or street lighting.
There are different methods of Energy Harvesting. So called the piezoelectric effect is generated by piezoelectric crystals electrical voltage when they are deformed by a force. On the windshield of cars are rain and light sensors attached to use the existing body vibration to produce energy. Thermocouples are also used, in which tension builds when they are exposed to temperature changes. Another possibility is an electro-dynamic transducer that, if he moves or pressure is exerted on it, produced by a magnet or a coil, a voltage pulse.
By Energy Harvesting only tiny amounts of energy generated, but these are enough to power small autonomous devices, such as wireless sensors. In public buildings energy-autonomous sensors are used to collect temperature or air temperature and thus to control the air conditioning. The mini-power producers have a number of advantages. Unlike battery powered sensors, they must not be serviced. Compared to wire systems need to lay any cables.
Even if only by sheer body heat, electricity can be generated. For example, the wireless medical sensor operation is possible. For the use of Ambient Assisted Living, special technical aids for people with assistance needs arise, new possibilities. Using energy harvesting can extend the operating time of mobile devices or unlimited standby times can be realized. Sensors were installed on bridges, which make up the vibrations. Some watches can be operated by the movement of the wrist. Window handles in mini-sensors have been integrated to report the opening of the window and then the heater off.
The applications are diverse and promising technologies. The research is still in its infancy. Although there are already many examples, there are still a lot of research and development needs, before traditional batteries may be permanently relegated to the scrapheap.