Water is the most important natural element, the subject of a cult, the basis of existence, the elixir of all powers and immortality. Thanks to its versatility it affects nearly all areas of life. A proof that water is an indispensable element of life originates in the beliefs of primeval cultures, for example in cosmological myths where this element appears nearly in the first place in the description of the world structure and order.
The Sumerian narrative poem Enuma Elish, the story of Gilgamesh, the Egyptian Book of the Dead, Homeric epics or the Book of Genesis at the very beginning make us plunge into primordial waters as the source of life, the reason for existence, the pre-matter. The above-mentioned literary works present a world that, according to old beliefs, emerged from an alternate reality, from the seas and oceans, from a state of rest, stagnation, inactivity. Quoting the Ionic philosopher, Thales of Miletus – “water is the primal element, the origin of nature, because all living things live thanks to moisture and dead things dry out, the seeds of all beings are moist and all feeding is juicy”.
Many archaic concepts depict this life-giving element as existing in illo tempore – in the beginning. Symbolic drawings referring to water and writings in the form of meanders, motifs of horizontal curves or zigzags, sometimes resembling a snake, could be found on the walls of the Altamira or Lascaux caves. Murals in caves, dating back to around 33-32 thousand years ago, although the peak was in the period of the Magdalenian culture (18-12 thousand years ago), not only reflect the world as it was in those times but they also provide evidence that already primitive people felt a need for creating the elements of sacrum around them. Hence, water turned out to be not only a drink for the thirsty but also a method of purification for the body but most of all a symbol of the most important of the elements.
Water was the fundamental and necessary element underlying the development of the first civilizations, having an effect on shaping human communities. Primeval societies located their settlements near water reservoirs that were a kind of guidance and marked out the route facilitating orientation, communication and use of adjacent territories. With time water courses were used for economic reasons – in crafts and afterwards in industry. Water was used for floating timber, fishing, washing clothes, taking a bath or simply for drinking. Slavic people called water – the “oldest empress”, “the sister of God” or “mother water” and perceived it as a female. According to folk legends it was the first element preceding the emergence of the world. Interestingly, this concept coincides with the beliefs of other cultures, including the vision of how the world was created according to the Bible where water appears to be one of the first elements of God’s command that gave rise to living creatures. According to folk tradition it was also a benevolent force necessary to ensure vegetation and abundance of crops.
In the cosmogony of the Ancient Near East – presented in the first of the preserved written texts, that is Enuma Elish – the world is created from chaos. The oldest myth of ancient Mesopotamia believed that the foundation of the universe was the chaos of the primeval ocean. It was personified as the goddess Nammu, having all the characteristics we now associate with water: fertility, all creative powers, self-sufficiency and the ability of creation. According to legends, she was the one to give birth to the Sky (An) and the Earth (Ki) – the future parents of the Air (Enlil). According to another version, the forefather Apsu and the foremother Tiamat emerged from the chaos of primordial waters and initiated the creation of the world. Interestingly, subsequent versions of this Babylonian myth suggest a bipolar nature of water both as a life-giving and purifying element and a dangerous, destructive force.
Indo-European mythology associates water – the natural symbol of life, health and immortality – strictly with goddesses and then with a deity of fertility. Water as a source of life was identified with the Earth and constituted a central part of the Universe. Its vast abyss was believed to be inhabited by monsters and demons – sea serpents, water nymphs or the aquarius. Water was the inevitable element of all magic rituals such as, for example, votive sacrifices or funerals.
Ancient Egyptians believed (although the papyrus evidence is scarce) that the world emerged from chaos, the primordial ocean. However, it is worth emphasizing that despite different variants of the myth about the creation of the world in the Nile Delta, water was always the leading element. Testimony is provided by songs praising the river, calling it the “lord of water who brings greenery”.
Greek culture and Homeric myth also depict Oceanus, embracing the world and symbolizing the vastness of primordial waters and the origin of all things. Life originated from the relationship between this primordial river-ocean and Tethys – the personification of fertility and the creative power of water. With time, myths started to recount that Mother Earth (Gaia) emerged from primordial waters to give birth to Uranus who filled all the gaps in earth with water, thus giving rise to all oceans, rivers and lakes. As the philosophical thought developed Greeks started perceiving water as the Arche (underlying substance) of nature, next to fire, air and earth. According to the beliefs, water was responsible for giving life and bringing death, for satiety and the abundance of crops or hunger.
In the Judaic tradition mentioned above, the world also came into being from chaos. The Holy Spirit emerged from the vast primordial waters and within seven days created the respective elements of the Universe. Water also has special symbolic meaning for Arabs – mainly in connection with its power to wash away daily sins (therefore, every believer before starting prayers should wash his body to emphasize his purity and thus readiness for talking with God). The Koran clearly indicates that this element was regarded as a gift from God and at the same time the source of life.
Water is of dual significance for respective religious traditions. On the one hand, it is an element necessary for life, symbolizing fertility or wealth (amber, fish). On the other hand, it is also an element bringing death, drowning, flooding and destroying things. The above-mentioned cosmogonies depict water as an element significant for mankind, co-participating in the work of creation and underlying all things. This idea is perfectly illustrated by one of the variants of this myth in which the disc of the Earth floats on the river-ocean (the Greek Oceanus).
In widely interpreted culture, water – thanks to its dual nature – was perceived as a life-giving force, unharnessed creative power, the essence of nature, which was translated into magic procedures, e.g. connected with fertility or welfare. In folk tradition (though not only), water and references to water denoted a female. Hence, childless couples often prayed for offspring to rivers. In turn, at dawn others drew water from the rivers to bake wedding bread and thus provide themselves with all graces and gifts. Slavs attached the highest importance to this life-giving element. It was also regarded as a boundary between the worlds – the earthly world and the unknown world – the land of the ancestors. According to ancient legends, a human soul on its way to the land of the dead had to cross the river of oblivion to get rid of its former life. Therefore, on the day of death or burial, the family of the deceased erected a footbridge across the river for the departing soul.
German tribes practised dumping corpses into swamps. Not very long ago, people living in Portugal, along the coast of Wales and near Brittany believed that humans were born during high tide and died during low tide. The origins of this superstition are ascribed to Aristotle who claimed that any living creature can die only during low tide.
Using the potential of hydropower became a milestone in the development of civilization thanks to a ground-breaking invention – the water wheel. The mechanism of the water wheel transporting water between different levels of the ground made it possible to irrigate desserts. The territories that were once uninhabited became settlement areas where crops could be grown. With time, the generated energy was used to drive equipment in saw mills or smithies. Before the period of the industrial revolution and the use of steam machinery, the simple design of the water wheel made it possible to generate clean, environment-friendly and stable power which could be stored by means of water damming.
Water wheels were in common use in ancient times, which is proved by archaeological discoveries in Egypt, Asia Minor and north Syria. Oddly enough, this invention appeared in many circles of culture in different forms almost in parallel. Researchers recount that the first water wheels were driven by an external force – manually or using a treadmill operated by people or animals. The earliest mention of this device could be found in the code of ancient Babylon in which we read that all thieves stealing water wheels used for field irrigation purposes would face severe punishment. Only the Greeks around the 3rd century BCE started using the water wheel (so-called noria) according to its name. Water current became the driving force. From that time we could say we were dealing with a primitive form of a water turbine.
The first wooden structures were quite simple and had a horizontal axis and a vertical plane of rotation. They were mainly used for irrigating fields or drying mines. The vanes put into motion by water current were at the same time buckets. They lifted water to a higher level and poured it into a wooden trough from which it flowed into irrigation channels. The operating principle was very simple – the rotating wheel transformed water energy into mechanical energy. Thus, one can say that the first primitive water turbines date back to that time.
In addition, the famous treaties on hydraulics by Phylo of Byzantium – Mechanike syntaksis (around the 3rd century BCE) described more complex designs of water wheels driving various toys. Reportedly, Pliny had a hydraulic organ in his garden). Phylo’s letters contained detailed instructions for operating two types of wheel: an undershot and overshot one. With regard to its original construction – a vertical axis and horizontal plane of rotation, the whole rotation was transferred directly onto millstones, making them turn.
With time, the development of engineering thought resulted in the use of a new type of transmission accelerating the rotation of the millstones. The system was described, among other authors, by a Greek traveller, Strabo, in the 1st century BCE and a little later by a Roman civil engineer, Vitruvius. It is worth noting that the mills presented by Vitruvius in De Architectura did not differ in terms of parameters from those built next to medieval monasteries. The Roman architect in his work comprising ten volumes presented wooden wheels with metal buckets or wooden chutes mounted on their circumference with water flowing down on them. A wooden gear at the end of the horizontal wheel axle caught the cog wheel of the vertical axle, while a millstone fastened with metal clamps was mounted on the top end of the axle.
Such devices appeared in Greece and then in Rome in 120-65 BCE, while they were brought to Northern Europe most likely from the East and in the Middle Ages became popular throughout Europe. The scale of propagation of the invention is evidenced, among other things, by numbers – in France at the beginning of the 12th century about 20 thousand water mills were in operation. At the end of the 13th century this number had doubled and in the 15th century as many as 70 thousand such installations were in use.
According to historical records, the first water mills made available to all inhabitants were set up in Rome around 398, whereas the water wheel alone was with time used as a drive for other tools.
The emergence of the water wheel became a breakthrough since it replaced primitive millstones or mortar grinding machines operated by humans. Initially, water mills – due to the high costs of construction and expensive operation – were erected at monasteries and monks were the first designers of water wheels. The “engineers in habits” are the ones to whom Europe owes using water fall force for driving the mill equipment on a larger scale.
The first mills were located in mountainous areas which did not require any special structures since natural downfalls of the terrain were utilized. In order to ensure the continuity of work, first adequate water flow should be maintained. Thus, it was necessary to build hydrotechnical units such as weirs or dams. Also, the bed of the watercourse had to be adapted properly, the banks had to be reinforced, dykes needed to be built and channels carrying water to the water wheel had to be dug. The channels were often several hundred metres and sometimes even a few kilometres long. Water flowed through the last section in a special wooden trough which carried it to the wheel, and was then recycled into the river or another water reservoir through another trough. Such a rotating engineering structure – thanks to a system of transmissions, belts and wheels – powered a whole range of machinery.
Water driving the mills needed a considerable flow rate although such structures did not have to be located on the bank of the river at all. Some structures were set up between two rafts anchored on navigable rivers called floaters. Their location could be adjusted by means of ropes wound on the shore. There were also mills “on scales”, that is, permanent structures set on piles driven into the bottom of the river and connected with the shore by a wooden deck. They were mostly wooden structures although wall bases were also constructed. On the other hand, mills situated within the premises of the monastery, sometimes fitted with more than one water wheel, were built from brick. At that time there was a rule that a single driving mechanism – the water wheel – moved a single working mechanism, that is, the millstone, mortar grinding machine or another device. According to historical sources, in France in the 4th century there was a group of mills with 16 water wheels.
The water wheels were built mainly from oak timber. The structures were on average from 50 to 100 centimetres wide and had diameters of up to three metres. Medieval mills made use of four types of wheel: horizontal (so-called Nordic mill), undershot (with vanes), breastshot and overshot (flume) wheel. The wheel type was always selected depending on the location of the mill and the type of watercourse. The simplest structure was the horizontal wheel which did not require a transmission since it was connected with the millstone by a rigid beam. As the name itself suggests, the wheel was mounted horizontally and the stream of water hit the vanes and put the whole device in motion.
In relatively flat areas overshot wheels were used. They did not require major engineering works. Such structures were the largest ones and their diameters reached three metres. They mainly used the kinetic energy of water, which was accomplished by mounting the wheel over the river bed. The water current hit the vanes mounted on the circumference of the wheel structure from the bottom, thus setting them in rotary motion against the water flow. The speed of rotation, and thus the performance, was largely dependent on the river’s current and water level. The wheel could be blocked by simple changes in the water level or a natural blockage caused, e.g. by tree branches. Thus, attempts were made to control the river flow – near the mill the river bed was dredged, the river banks were reinforced, the main current was shifted or artificial river branches were formed in order to maintain the water flow at a fixed level. Despite numerous improvements in the 19th century aiming to enhance the performance of this model of a mill, the efficiency of the devices installed was not high.
Overshot wheels required more investment and engineering works but their performance normally ranged between 70 and even 80%. They mainly used potential energy since they were set in motion by dammed water brought to the flumes of the wheel from the top so the wheel turned in the direction of the river flow. The current of the water stream was also significant (kinetic energy). Engineers found it important to ensure adequate damming of down flowing water (at least equal to the height of the wheel) so that it would generate more energy. Therefore, during the construction of overshot mills a number of additional equipment was built and suitable terrain was selected. A continuous stream flowing in at a specific rate required a fixed water level in the upper pond responsible for damming water.
The use of a gate weir came as a solution. It comprised gates moving in vertical guides on the lock that could be lifted or lowered by means of a chain or a gear transmission operated with a winch. The dammed water fell down from the upper pond via a wooden work flume (resembling a trough with a small downfall, supported on piles driven into the soil) onto the wheel and flowed down to the water reservoir below the mill – so-called lower pond – from which it flowed into a river or a breeding pond.
The fourth type – the breastshot wheel – also made use of both potential and kinetic energy because water hit the wheel in the middle of its diameter and thus increased its pressure surface. Such devices were characterized by the highest efficiency, that is, 80%, but their design requirements were very high. Adequate water damming was necessary to ensure that it reached the wheel a little above the mounting point and proper water vessels had to be mounted in place of the vanes. The structures were suitable for mills situated by streams with a fixed flow of large volumes of water, therefore they only became popular in the 18th century. This type of water wheel is deemed to have been invented by an English civil engineer and machine designer, John Smeaton, whose water wheel design contributed to the later invention of a water turbine. Water mills and water wheels are excellent monuments of engineering thought that perfectly illustrate the development of engineering and the human ability to use the potential of the forces of nature. It turns out that these simple driving devices – starting from water wheels to more complex flume wheels – as early as in the Middle Ages could develop about 3HP – comparable to the power of the present-day lawn mower. Until the 18th century the performance of those structures was not much better since it depended on the degree of water damming and on the size of the water wheel.
In Poland mills appeared in the 12th century in the period of feudal economy and their decline saw the expansion of the 19th-century engineering thought. According to historians, the mention of a water mill in Poland dates back to 1145 and refers to the duke’s grant for the monastery in Trzemeszno, and another one for the monastery in Lubiąż in 1175. Initially, the owners of the mills were kings, bishops or liege lords. Water structures were most often erected in Pomerania, Greater Poland, Silesia or Lesser Poland – more rarely in Kuyavia and Mazovia. In that period two privileges clearly indicated that the decision to build another mill or start production was up to the liege lord. In addition, milling operations could be performed only in the place indicated by a magnate. Therefore, peasants were forced to use the services of a mill owned by the land owner and thus provided him with regular income. All those restrictions made the miller a profession for the chosen – very prestigious and indispensable in a rural area. With time millers formed a closed circle and crafts became a hereditary occupation similar to other professions. Craftsmen working in the mills could be: hired workers, legacy workers and workers paid in kind. Hired workers signed a contract of lease of the mill and they were required to maintain and properly use the equipment. It mainly referred to manor mills from which the whole income was handed over to the owner and the miller himself received a small payment, most often in the form of grain. The most numerous group of craftsmen in the 18th and 19th century were workers paid in kind. In consideration for their services they received grain or flour and had to give a specified part of this in-kind payment to the lease owner. Legacy millers had the highest rank in that group since the title of ownership of the mill depended on whether it was bought out from the previous owner or purchased under a contract providing for the right to erect a mill on a specific plot of land. Hence, the craftsman having his own mill could manage it on his own but every transaction had to be approved by the liege lord.
Millers were highly respected although sometimes they were accused of relations with evil forces and even of having superpowers. According to folk legends, a demon called aquarius was the millers’ helper. Still at the beginning of the 20th century sacrifices were made to ask for rainfall in dry times or to protect local households from flooding. Thanks to their stable work position millers were better off in the rural community. They were distinct from villeins (peasants) not only in connection with their peculiar clothes but also the way of speaking their skills since they combined: commercial, accounting, technical and agricultural knowledge with practical skills: carpentry, cooperage, building or mechanical works. Thus, it can be said that they were comprehensively talented and sophisticated although they were often accused of being dishonest or mean.
The 19th century brought intensive development of engineering thought, mainly in connection with the progress of technology, including the propagation of water turbines. In 1827 the French engineer, Benoît Fourneyron, put into operation the first reaction turbine. Its construction is the result of Bernoullie’s work or early experiments by Segmer and Bourdin. Many researchers emphasize that Euler’s underlying operating principle of a turbine of 1754 contributed to a large extent to achieving the capacity of 80%.
In 1848 James Francis’ axial-radial flow turbine turned out to be a ground-breaking invention. The American inventor largely employed the ideas of his predecessors but it was his design that achieved 90% capacity. From the point of view of the flow kinematics in the water turbine the operation of the centrifugal pump is reversed. Water from the main reservoir was flowing through the vanes and, gaining quite a considerable speed, it supplied power to the working rotor. Having flowed between the vanes, the water left the rotor at high speed and entered the suction pipe. It was accompanied by a hydrodynamic reaction which set the rotor in motion against the water outlet.
The invention of another type of turbine, the so-called impulse turbine, was another milestone for the “white coal” energy industry. In 1840 Lester Allen Pelton working with a “spray wheel” put forward a solution in which the vanes were set at an angle of 90 degrees to the water stream. In its turbine the American inventor, to increase its capacity, used properly profiled vanes resembling two connected cups on which the water stream changed its direction more gently.
The development of a new type of turbine – the so-called propeller turbine – in 1921 made a significant contribution to the present shape of hydropower engineering. Initially, the Austrian engineer designed a propeller engine, then a rotor with adjustable vanes resembling marine propellers. The idea made it possible to change the angle of inclination of the vanes in operation and, as a result, the power of the engine could be controlled and its efficiency could be increased. Undeniably, the development of water turbines was influenced by engaging them with current generators, which made it possible to transmit electricity considerable distances. The first such power plant to tame water was built on the River Fox in Appleton, in the United States of America, in 1882. The investment satisfied the energy requirement of a paper mill. It is worth mentioning that the first hydroelectric power plant was put into service two years after the spectacular presentation by Thomas Edison where a wide audience could see for the first time how electric light was produced. The popularity of hydroelectric power plants increased year on year. In 1886 as many as 45 such facilities were registered in the United States and Canada. In 1889 the number of power plants in the USA reached about 200.
The first hydroelectric power plant in Poland was built in 1896 in Soszczyce on the river Słupia. It was equipped with a 250 kW Francis turbine. Before World War II, in 1923, in Gródek in the region of Pomerania, the largest hydroelectric power plant in Poland was put into operation. At that time it generated 4 MW of power and supplied electricity to Gdynia. In the thirties a number of larger power plants were built, including plants on the rivers Dunajec, Soła and San. When the turmoil of war came to an end, as a result of territorial changes Poland acquired a dozen or so power plants, including those in Pilchowice and Dychów. Most of the investments were implemented in the 1960s when a number of large power plants were put into service, e.g. in Koronowo, Myczkowice, Dąb, Solina, Tresna, Żydów and Włocławek.