Mills and turbines

When dealing with human consumption of water, that corresponding to basic needs is, in reality, very scarce and a good part of domestic consumption can be reduced with a little effort. In reality, the large consumers of water are the industries and power plants that receive, respectively, more than 60% and 90% of the water coming from rivers, lakes and
reservoirs.

Look at the following table and the number of liters of water needed to produce the different consumer products. Compare them with the domestic consumption data.

Although hydroelectric plants are currently the main consumers, the use of water for energy purposes is nothing new. The great capacity of water to store heat energy was and is the basis of steam engines and turbines. Many industries use this same capacity to cool or heat in some manufacturing processes.

Think of daily activities or devices that you use regularly and that work with water, taking advantage of it either to release or absorb heat. There are a lot of belongings: from the car radiator to the iron or the heating in your house. How do they work? How do they use the water? Think of industrial processes you know of that need water.

So far we have referred to the energy of heat; We could also talk about the use of hydraulic energy, that is, the energy that is derived from moving water and benefits from the fact that its mass/volume ratio is very high (1 t/m3 at 4o C). While it is true that the transformation of hydraulic energy into electrical energy is a relatively modern phenomenon, it is no less true that hydraulic energy was already used in different versions of mills to grind grain, make pulp or press olives.

The water is conducted from the dam to the turbines, located at a lower level precisely in order to make better use of its kinetic or movement energy. The water turns the turbines that drive the generator, which, in turn, produces electricity.

Paper mills

Paper mills that used the power of river water to make paper have a long tradition in many countries. It seems that paper was invented in China in the 2nd century BC. Egyptian papyri have also been known since ancient times, as well as a kind of paper made by the Aztecs in the 10th century.

In a paper mill, hydraulic power was used to move large mallets that shredded and shredded the rags (which used to be made of linen or cotton until the beginning of the 20th century and which constituted the raw material, the vegetable fiber with which to make paper ); In reality, the water moved a wooden wheel, the paddle wheel, which, in turn, moved a structure linked to the mallets: a kind of axis that made the mallet, going up and down, crush the rags with some iron nails that he had at the ends.