It is surprising that the image that accompanying a new in the webpage of a Technological Centre as Gradiant is a shower picture, similar to the showers that anyone can have in their own home. The reason for this fact is that the shower that we present in this article takes advantage of one of the technologies on the rise in the recent times and that is already in everyday use today: the energy harvesting. This shower is unusual because it includes a hydro, which is able to harness the kinetic energy generated by the flow of water to produce electricity. This energy is used to power a temperature sensor and a set of LEDs according to the measure obtained by the sensor (red LEDs in the case that the temperature exceeds a set value, blue if it is below another threshold and green when the measure is in the optimal range).
Focusing on technology that provides support for this application, energy harvesting is the process by which a device is capable of exploiting the residual energy in the environment to produce electricity which will then be stored or used to power low-power systems. Thus, exploit other types of energy present in the environment to power systems that can be fully autonomous. In addition to the energy produced by the flow of water like in the example application (known as hydro), there are numerous sources of energy in our environment such as electromagnetic radiation present in the air (such mobile and television broadcasting signals), the wind (wind power), vibration or pressure changes (using piezoelectric materials), light (using photosensitive materials such as photovoltaic cells), temperature gradients in the environment (through the use of thermoelectric materials based on the Peltier principle) or the oxidation of some compounds, such as blood sugar. The sources cited in this text are only a small fraction of the energy harvesting mechanisms present in the state-of-art of this technology, where many applications have been developed, such as sensors that monitor intracorporeal medical variables independently obtaining energy from the oxidation of blood sugar, a system that extracts energy from the movement of a person and feed it to his MP3 or a network of sensors on trees that use the energy created by their metabolic process for energy supply. The value of this technology lies precisely in its ability to make that the systems in which this techniques are used (currently, its use is closely linked to sensor networks) have a virtually unlimited autonomy if they can continue to collect energy from the environment despite connecting to the mains or batteries replacing processes. It is also a valid solution to power sensors in hard to reach places.
Gradiant follows closely the evolution of energy harvesting, carried out some experiments based in the use of thermoelectric material to use the thermic energy of the enviroment. This set of technologies is emerging as a key to a future in which energy efficiency and monitoring the environment will be indispensable to the new technology services and, therefore, Gradiant is moving in this direction.