Volume 6 hydro power 6 11 – evolution of hydropower in spain

Volume 6 hydro power 6 11 – evolution of hydropower in spain Volume 6 hydro power 6 11 – evolution of hydropower in spain Volume 6 hydro power 6 11 – evolution of hydropower in spain Volume 6 hydro power 6 11 – evolution of hydropower in spain Volume 6 hydro power 6 11 – evolution of hydropower in spain

F Bueno, University of Burgos, Burgos, Spain

© 2012 Elsevier Ltd All rights reserved

References

6.11.1 Hydroelectric Power in Spain

6.11.1.1 Electric Power and Hydroelectric Power

In the first years of hydroelectric power development in Spain, at the end of the nineteenth century, it was the thermal plants that covered most of the electric power demand With the general use of alternating current and transformer stations this changed, and in the first four decades of the twentieth century hydraulic power increasingly became the main source of supply, reaching 93% of the total supply in 1936

With slightly lower values, this relevance was maintained until, from the first years of the 1960s, a large number of classic thermal power plants started operating, and nuclear power plants started from the beginning of the 1970s, which meant that in

1975 hydroelectric production was only 35% of the total In this century, the construction of combined cycle power plants and wind farms has led to the current situation, in which the installed hydroelectric power is 20% of the total and the coverage of demand is around 12% in an average year

Thus, the installed hydroelectric power at the end of 2008 was 18 700 MW, from which 16 700 corresponded to the ordinary production system and 2000 to mini power plants under the special production system, over an installed total of all types of energy

of 96 000 MW Combined cycle power plants are those that provide the highest installed power to the group, whereas wind power is practically the same as hydroelectric power (Figure 1)

As for energy produced, hydroelectric power accounted for 26 000 GWh in 2008, from which 21 500 corresponded to the ordinary system and 4500 to the special system, compared to the nearly 295 000 GWh of the system’s total net generation (Figure 2) These values are below average, the average being 35 000 GWh, as 2008 was a dry year

The pluviometric irregularity that characterizes the Spanish territory results in irregularity of superficial runoff and, as a consequence, affects hydroelectric production In 1979, good hydraulicity resulted in attaining an absolute maximum hydroelectric production of 47 473 GWh, which meant 45% of the total On the contrary, the drought in 1992 resulted in the energy produced only reaching 20 750 GWh, which meant 13% of the total

Combine cycle 24%

13%

Fuel/gas 5%

Nuclear 8%

Coal

Wind 17%

Special regime 32%

Hydraulics 2%

Other renewable 5%

Nonrenewable 8%

Combine cycle 32%

Fuel/gas 1%

Nuclear 20%

Special regime 24%

Coal 15%

Wind 11%

Hydraulics 2%

Other renewable 3%

Nonrenewable 8%

Figure 1 Installed electrical power at the end of 2008

Figure 2 Electric power production in 2008

6.11.1.2 The Strategic Importance of Hydroelectric Power

Hydroelectric power has a series of important qualities that make it one of the most strategically important energies from the technical, economic, and environmental points of view From a technical point of view, due to its high degree of use in comparison

to its potential, as the high efficiency of the turbines and alternators must be added to the low load losses in intake and return pipes, achieving a global efficiency of the plants between 85% and 90%, which has never been achieved in any other type of power plant From the economic point of view, the cost of the raw material is very low or nil, which affects the total generation costs very favorably From an environmental point of view, its main characteristic is in the nonemission of greenhouse gases Each hydro­electric kWh avoids the emission of up to 1 kg of CO2, 7 g of SO2, and 3 g of NOx The average production in Spain is equivalent to not emitting 35 million tons of CO2

In addition, the developments related to regulation reservoirs and pumping provide a high quantity and guarantee electrical energy supply, facilitating load curve management and the regulation of frequency and voltage They are also an installed power reserve in view of possible unavailability of other types of generation

Besides, hydroelectricity is a source of energy in itself, an important fact in a country and high energy dependence National hydroelectric production in an average year is equivalent to that obtained with 6 billion cubic meter of natural gas, 13.2 million tons

of coal from abroad, or 9.3 million tons of fuel in plants that consume these fuels The cost of avoided imports may amount to nearly €1100 million in the case of gas, €680 million in that of coal, or €1900 million in that of fuel

6.11.1.3 Hydrology, River Network, and Hydroelectric Development

The average annual precipitation in Spain is around 650 mm and is characterized by its irregularity, both spatial and temporal Spatial irregularity results in two differentiated areas: Wet Spain and Dry Spain (Figure 3) Temporal irregularity of precipitations results in that for any considered period – multiannual, annual, or seasonal – the gap between the maximum and minimum values

is very big To this we need to add a high evapotranspiration, which makes the average value of runoffs around one-third of precipitation From the 330 000 hm3 of precipitation, only around 110 000 become runoff

All this results in the natural regulation level in Spain being close to 6–8% The current regulation level is around 40–42%, for which it has been necessary to build more than 1300 large dams Without them, economic and social development in Spain throughout the twentieth century would have been impossible (Table 1)

The Spanish hydrographic network is characterized, in a first approach, by the existence of rivers with two types of structure, some with a well-developed river network (considerably long tree-shaped riverbeds with a large number of tributaries) and others with rather parallel riverbeds and short in length

Among the first we find the Miño, Duero, Tajo, Guadiana, and Guadalquivir that flow into the Atlantic Ocean, and the Ter, Llobregat, Mijares, Ebro, Júcar, Turia, and Segura that flow into the Mediterranean Sea The second type are characterized for flowing

in a perpendicular direction between the Cantabrian mountain ranges and the Cantabrian Sea in the north of the peninsula, and between the Andalusian mountain ranges and the Mediterranean Sea in the south The proximity of these mountain ranges with the coast give these rivers characteristics of short lengths, steep slopes, perpendicularity to the sea, and the nonconnection between them despite being close to each other (Figure 4)

From the river network structuring point of view, in the first type not only has the full use of the main rivers with their tributaries been possible, but also in some cases full use of both has been possible This layout of the river network has favored a higher use of

70−300 300−600 600−900 900−1200 1200−1600

>1600

Figure 3 Spatial distribution of precipitation in the peninsula

Table 1 Natural regulation and artificial regulation by hydrographic basins

Natural Reservoir Available Available Natural resources Natural regulation regulation capacity resources resources Basin (hm3 yr −1) (hm3 yr −1) (%) (hm3) (hm3) (%)

some of the tributaries, fed by high and medium-height mountains, than those of the main rivers, whose middle sections are less steep and whose use has been destined to irrigation In the rivers of the second group, hydroelectric use has followed classic steep development schemes

Hydroelectric development of the rivers in Spain has been conditioned by competition with other uses: that of supply and especially that of irrigation Currently, 70–75% of the consumptive uses of water are destined to irrigation, which occupy the center

of the Atlantic river basins and the lower sections of the Mediterranean rivers, with the consequential need of regulation reservoirs at the headwaters of its tributaries, on mountain fringes The development of irrigation began in the early twentieth century, at the same time as the origins of hydroelectric development, being direct competitors in some lands

6.11.1.4 Power Plants and Main Developments

There is a great variety of hydroelectric plants, both regarding the size and the facilities characteristics In 2004, there were more than

1500 plants, including mini power plants under the special system There were nearly 900 power generation units under the ordinary system

There are five power stations with more than 500 MW and 21 with more than 200 MW, which represent more than half the installed power Another 14 power stations exceed 100 MW and represent 12% of the power; those that exceed 50 MW represent 14% and those with less than 50 MW, including mini power plants, the rest (Table 2 and Figure 5)

The largest plants are those of Aldeadávila I and II, with 1243 MW, Jose M de Oriol with 933 MW, Cortes-La Muela with

915 MW, Villarino I and II with 810 MW, and Saucelle I and II with 520 MW The first, fourth, and fifth are located in the Duero System, the second in the Tajo river, and the third in the Júcar river

Table 2 Hydroelectric power plants in Spain with an installed capacity of more than

100 MW

Pumping capacity Hydro plant Turbining capacity River (MW)

Aldeadávila I and II 1.243 Duero Pure 435 José María Oriol 934 Tajo

Cortes – La Muela 915 Júcar Pure 635

Saucelle I and II 520 Duero Estangento – Sallente 451 Flamisell Pure 451

Tajo de la Encantada 360 Guadalhorce Pure 360

Villalcampo I and II 227 Duero Castro I and II 194 Duero

Ricobayo I and II 328 Esla

Cíjara I and II 102 Guadiana

Approximately 10 000 MW have a high seasonal regulation, of which 2500 MW are equipped with pumping There are around

2350 MW in important power systems but with scarce regulation, and around 1300 MW in developments at the base of a dam The rest of the hydroelectric facilities consist of small power plants, many of run of rivers

Spain’s hydroelectric potential is estimated at around 162 000 GWh yr−1, of which a little over 64 000 GWh are technically usable Taking into account that average yearly power production is around 35 000 GWh yr−1, there is still technical margin available The economically viable potential is estimated at 37 000 GWh, in accordance with the most recent data, not including the pumping plants This means that Spain is close to the economically acceptable ceiling However, some clarifications must be made On the one hand, this ceiling is moveable, as it depends on the economic conditions not only of the jumps themselves but also, and especially, of the power production strategies at national level, which depend on the degree of dependence, on power vulnerability, on petrol and gas prices, or on the consideration of other types of plants’ environmental costs, among others On the other hand, power production is far from this level in the last few years, partly due to low rainfall Exploitation during these dry years may be increased by building new facilities or improving the existing ones

6.11.1.5 Producing Companies

The large electric utilities that have hydroelectric power stations in Spain are Iberdrola, Endesa, Gas Natural SDG, Acciona, E.ON España, and HC Energía The last two concentrate their hydroelectric activity mainly in the north part of the peninsula, while the others distribute their facilities over greater areas of the national territory A high number of other small companies must be added

to these large ones, including those that have mini power plants with less than 50 and 10 MW and that are subject to the special electric production system The Administration is also the owner of a high number of toe of dam schemes, most of these in dams intended for regulation for irrigation or integral regulation of rivers

Iberdrola is the result of a merger in 1991 between Iberdrola and Hidroeléctrica Española and owns 9187 MW Iberduero had its origins in Hidroeléctrica Ibérica, founded in 1901, and in Saltos del Duero, founded in 1918 with the purpose of exploiting the great hydroelectric potential of the Duero System They were merged in 1944, soon after joined by Saltos del Sil, born to exploit the great hydroelectric site of the Sil river and its tributaries Hidroeléctrica Española was founded in 1907, with its origins also being some of the schemes and concessions of Hidroeléctrica Ibérica The main hydroelectric development of Hidroeléctica Española took place in the Júcar and Tajo basins

Endesa, with a current installed hydroelectric power of 4511 MW, was created with public funding in 1944 with the purpose of helping the private sector in hydroelectric development In 1983 the Endesa group was created, with the acquisition of some electricity companies such as Enher or Gesa, among others, from the National Institute of Industry

In the 1990s it acquired Electra del Viesgo, the historical Sevillana de Electricidad, Hidroeléctrica de Cataluña, and Fuerzas Eléctricas de Cataluña

Unión Fenosa was the result of the merger between Unión Eléctrica and Fuerzas Eléctricas del Noroeste (FENOSA) in the year 1982 The first had its origins in 1889, with the creation of the Compañía General Madrileña de Electricidad, which after several groupings became Unión Eléctrica Madrileña in 1912 The second was created in 1943 to exploit several hydroelectric schemes in Galicia, in the northeast of Spain Recently, Unión Fenosa has merged into Gas Natural as Gas Natural SDG has a hydroelectric power of 1860 MW Acciona acquired Energía Hidroeléctrica de Navarra and assets from Endesa, Saltos del Nansa among them, to achieve the 857 hydroelectric MW

The presence of E.ON is more recent, as it dates back to 2007 through its renewable energies affiliate and to 2008 as a market unit and as E.ON España, with 668 MW This presence is due to the acquisition of assets from Ente Nazionale per L’Energia Elettrica (ENEL), who in turn had acquired the old Electra de Viesgo from Endesa, one of the Spain’s historical companies created in 1906 The historical Hidroeléctrica del Cantábrico has merged into the EDP group (Electricidade do Portugal) in the last few years under the name HC Energía It has 433 MW of hydroelectric power

6.11.2 Evolution of Schemes and First Developments

6.11.2.1 Periods in the Evolution of Development

The demand of electric energy has been increasing from the first days until today, with variable rates according to economic growth

in general and the industrialization level in particular The relationship between the industrialization and electric energy demand has always been similar This demand has been met throughout the twentieth century with different types of power plants, among which hydroelectric power plants have had varied importance

The distribution of generation to satisfy such demand between the different stations has depended on several factors, among which we must mention the hydroelectric potential and its level of exploitation, the cost of produced power and the environmental problems of the different power plants, or the strategic decisions to protect different sectors of the national economy, just to mention some of the main ones The political and economic situation was also important in Spain in certain periods as it conditions the availability of equipment and building technology, as we will see later on From a technical point of view, the main factors were those corresponding to the state of the art of the technologies available for those elements that affect hydroelectric developments: turbines, turbo pumps, or generators, as well as hydraulic engineering, dam engineering, and tunnel engineering, essential elements

in Spain’s hydroelectric development

Figure 6 (a) Installed power in Spain between 1880–1940 period (b) Generated power in Spain between 1880–1940 period

All these factors have contributed to the variation of the development and the hydroelectric use systems and their importance in the electricity sector in Spain throughout the twentieth century, with clearly different characteristic periods

The first period goes from the first steps of electrical energy in Spain to the civil war (1890–1940), characterized by an important increase of installed power and of produced energy, especially since 1910 After some years during which thermal power plants supplied most of the energy, with the new century it was the hydroelectric power plants that began to absorb most of the demand In

1940, the installed hydroelectric power was 78% of the total and the generated power was 93% (Figures 6(a) and 6(b)) The 1940–73 period is characterized by the importance of hydroelectric production, which represented more than half the total electric production From 1973, the increase of thermal production in classic and nuclear power plants made hydroelectric power stop being the main source, and has from then on lost relative importance in terms of energy (Figure 7)

If we take other factors into account, we can clearly distinguish two different phases within this period One is from 1940 to the second half of the 1950s, characterized by the use of building equipment already used before the civil war, as a result of the autarchic politic and of Spanish isolation, which meant a certain continuation of previous productions

The second period begins with the change of decade from the 1950s to the 1960s, during which the confluence of several factors allowed for the great development of hydroelectric power The great development of dam engineering, the development of reversible power units, and the cost reduction in the construction of all types of works – hydraulic, underground, mechanical, and so on – due to the availability of new equipment, are the reason for the quick evolution in the development schemes On the other hand, the more constructive and economic facility in underground works allowed for a greater flexibility in hydroelectric schemes, making it possible to build developments unthinkable just a few years before From then, the construction of underground power plants and reversible power plants were commonplace

From the middle 1970s, the increase of installed power continued increasing, but less than the classic thermal or nuclear power plants, despite of which the produced power stagnated to previous levels, with the exception of very favorable years in hydrological

020040060080010001200140016001800

HydropowerThermal powerTotal installed power(a)

(b)

05001000150020002500300035004000

HydroThermalTotal generation

Figure 7 (a) Installed power in Spain between 1940–2008 period (b) Generated power in Spain between 1940–2008 period

terms From 1990, the increase of installed power has been very little mainly due to electric system regulation installations and power increases in already existing plants (Figures 7(a) and 7(b))

In the last decade of the past century, a construction process of small plants and the renovation of others that were not in use began

In the origins of this process we find, on the one hand, the development of more and more reliable power units and the remote control and/or centralization of operations, with the corresponding reduction of maintenance and operation costs and, on the other hand, the inclusion from 1997 of these plants in the special electricity production system, whose purpose is the promotion of renewable energy

In each one of these periods, hydroelectric power and hydroelectric developments have had clearly different characteristics 6.11.2.2 The 1890–1940 Period

6.11.2.2.1 First steps of electricity in Spain

The first reference to the practical application of electricity in Spain dates back to 1852, when the pharmacist Domenech lit up his premises in Barcelona with a method invented by him That same year lighting tests were carried out in several public spaces using galvanic cells From then on, and with a higher intensity in the 1870s, certain areas of some cities began to be lit up, generally using dynamos powered by steam engines

The production of electrical energy in important quantities for that time began in the mid-1870s, using thermal power units powered by coal and low-quality gas The first electricity supply contract dates back to 1876, Sociedad Española de Electricidad was the first Spanish electricity company In 1878, several squares, streets, and important buildings in Madrid were lit up, and at the beginning

of the next decade in cities such as Valencia and Bilbao Increasing demand in the last two decades of the nineteenth century resulted in several companies being established with the only purpose of supplying electricity, both for public and private use

In the last few years of the nineteenth century and in the beginning of the twentieth century it was supplied as direct current, which forced the power plants to be located near the consumption centers, which in turn limited the building of hydroelectric schemes and favored the use of thermal power plants With the first use of alternating current in the last few years of the century and its great development in the first decade of the twentieth century, the limitations of the location of hydroelectric power plants disappeared, making the boom that took place during the second decade of the century for this type of energy possible

In 1901 there were 861 electric power plants in Spain, with a total installed capacity of nearly 100 MW Around 65% of them were thermal and 35% were hydroelectric, 650 mostly dedicated to public services, and the rest for private use More than half of the total, around 510, produced in direct current and the rest in alternating current The uses of this energy were around 87 000 incandescent lamps and 1500 arch lamps for public lighting, and 1 240 000 incandescent lamps, 2800 arch lamps, and 2036 engines for private use 6.11.2.2.2 The electricity sector in the first decades of the twentieth century

In the 1901–30 period, the total electric power was multiplied by 12, reaching 1200 MW, which became 1600 MW in 1936, a number that slightly dropped at the end of 1939 as a result of the civil war destructions, which paralyzed the development of the Spanish economy This big increase of installed power resulted in there being a small excess of installed production over consumption during this period Increase in demand was variable: 8% between 1901 and 1922, 10% up to 1930, and 5% up to

1936, very similar values to those of economic and industrial growth

If in 1890 installed hydroelectric power in Spain was 30% of the total electric power, this percentage went up to 69% in 1910 and 77% in 1920 This percentage would become stable until 1936, the year the civil war paralyzed electric development As far as production

is concerned, these percentages were even more favorable for hydroelectric power plants due to a higher amount of operation hours than those of thermal power plants So, in 1929, 81% of production was hydroelectric This percentage rose to 93% in 1936 (Figure 6) Apart from the general use of alternating current, the origins of this development lie in the fewer total costs of hydroelectric power despite a higher initial investment, this was not only due to the zero cost of water but also to the increase in the cost of coal, gas, and petroleum products throughout these first few decades

The construction of hydroelectric schemes of considerable size was generalized from the last years of the century’s first decade to cope with the demand, which involved high economic investments This was only possible due to the creation of a large number of electricity companies intended for production and distribution, which was led by private initiatives and with important participa­tion of the banking sector

6.11.2.2.3 Main hydropower developments

Between 1901 and 1902, the first large (for that time) hydroelectric plants began operating, among which we must mention those of Molino de San Carlos, near Zaragoza, Navallar, on the Manzanares river, the first to supply this type of power to Madrid, and San Román, on the Duero river near Zamora

The Navallar power plant, with 1750 CV installed in four power units was the first of series of facilities that supplied power to the capital city from the rivers located to the north of it (Figure 8) The source of the scheme was the first dam of Manzanares el Real, with a height of 10 m and which was raised in 1906 A canal flowed from the dam which, apart from feeding the plant’s surge chamber, served as a reservoir from which water was pumped to the city of Colmenar It was one of the first important dams destined for hydroelectric and multiuse purposes

The San Román power plant, which had an installed capacity of 5000 CV and took advantage of a long meander of the Duero river, with a 6 m-high dam and a 15 m head meant an important leap in terms of installed capacity, superior to those built until then Until 1910, a large number of similar schemes were built, most of them with installed capacities of 1500–2000 kW and located in medium river watercourses Most of them were characterized by their diversion schemes, with a weir, a canal which was not too long and flowing parallel to the river, a small surge chamber and one or more horizontal configuration power units with Francis turbines

In 1909, the Salto de Molinar, on the Júcar river, was inaugurated It was the most remarkable hydropower project built in Spain until then The development has been historically considered as one of the best and most profitable in Spain It was projected for a production of 70 GWh, when Madrid’s consumption was 30 GWh Three 4500 kW power units were initially installed, in the following year an additional power unit was installed, achieving an installed capacity of 22 500 kW If the development was

Figure 8 Navallar power plant (1902) Cross-section and inside the power plant

Figure 9 Molinar power plant (1909)

important for its singular technical characteristics, it was also important for the transport line, 250 km long with a voltage of 60 kV, which supplied power to Madrid This line was Europe’s most important one at that time (Figure 9)

For similar purposes, the Villora project meant another leap in hydroelectric development in Spain Located on a tributary of the Júcar river, the Cabriel river, it had an installed capacity of 12 000 kW The scheme comprised a dam, a tunnel that crossed the watershed with a tributary of the Cabriel, and a power plant that hosted two horizontal axis power units A second dam that regularized the turbined waters completed the system In 1925, the increase in demand in the Madrid area made it necessary to install a new unit that doubled the installed capacity, which was the first vertical axis power unit installed in Spain A new power unit, similar to the previous one, was installed in 1945, after the war, with the purpose of collaborating in relaunching the battered Spanish economy (Figure 10)

Figure 10 Villora power plant In the foreground are the two vertical power units, one of them the first of this type in Spain Behind and at a lower level are the two initial horizontal axis power units

In the same Júcar–Cabriel system as the previous ones, in 1928 the Millares project works began, inaugurated in 1933 with two

20 000 kW vertical power units, those with the highest installed capacity in Spain until then, to which others were added in 1933 and 1942, achieving an installed capacity of 80 MW in 1942, which were very important at that time

The power supply to Madrid had, apart from those already mentioned and several others, the Bolarque project, which was put into operation in 1910 Its scheme, even though it was also a bypass, was different from the others as it had a more regulated reservoir and a short high capacity canal of 60 m³ s−1 The connection line with Madrid was important, to which it supplied electric power, with a length of 78 km and a voltage of 50 kV After completing in 1952, a rise with which the dam went from being 26 m above the riverbed to being 37 m above it, a power plant was built at the base of the dam, with pressure intakes, taking better advantage of the regulation and height A pumping station was also installed to safeguard the watershed between the Tajo basin and the headwaters of the Tajo-Segura water diversion canal, with a north to south course crossing a large area of the eastern part of the peninsula, taking water for supply and irrigation purposes to an important part of the Mediterranean basins (Figure 11) The first important hydroelectric development in Catalonia was that of Salto de Capdella, built from 1910 to 1914 in the Pyrenees, which supply power to the city of Barcelona It uses the waters of the upper watercourse of the Flamisell river, a tributary of the Noguera Pallaresa river, in turn one of the main tributaries of the Ebro river Collection and regulation takes place in 28 glacial reservoirs interconnected by means of canals and tunnels, all of them located between 2140 and 2534 m above sea level Nine of these reservoirs were raised with 10–20 m-high dams The lower reservoir, which collects the waters of all the others, is that of Estany Gento, from which nearly 5 km canal flows to feed two pipes that supply the water to the turbines Four power units with Pelton turbines of 8500 CV each were initially installed

Along with the singularity of collection and regulation, due to its height, we must mention the head of 836 m, the highest in Spain and one of the highest in Europe at that time (Figure 12)

Figure 11 The Bolarque power station and dam are in the foreground, the power plant is at the base of the dam At the back is the pumping station for the Tajo-Segura diversion

Figure 12 Capdella power plant: Diagram of the scheme and photograph of the power plant

Figure 13 Evolution of development schemes in the middle watercourse of the Noguera Pallaresa

Downstream from the Capdella power plant, three other power plants turbined the waters coming from it and from its own basins, one of them, that of Molinos, with a head of 273 m and an installed capacity of 13 500 kW The system of these schemes was the same as interconnected bypass jumps, so they did not need a dam

The next step in the exploitation of the Noguera Pallaresa did not follow this scheme For the middle section of the river, between the confluence of the Flamisell and its confluence with the Segre, the first phase of the studies planned the construction of two diversion schemes with parallel canals near to the riverbed The next phase of the studies was carried out after the unification of both concessions, both from the administrative and from the technical points of view This solution seemed to be a complex one and it was decided that the first section was to be exploited with a dam and a station at its base: the Talarn power plant The advantage of this solution was the achieved regulation, which would exploit more efficiently downstream (Figure 13) This type of evolution was commonplace during the first two decades of the century

In 1916 the construction of the Talarn dam and power plant ended, which acted as the primary regulation of the Noguera Pallaresa river It was the first large reservoir of hydroelectric use in Spain, with more than 200 hm³ achieved, thanks to the

86 m-high dam, which was the highest at that time and one of Spain’s dam engineering milestones The power house is located half way down the slope on the left margin and initially had four Francis power units with a total power of 30 000 kW (Figure 14) With this record, in 1920 the construction of the Camarasa dam ended It was 103 m high and with spillway capacity for 2000 m³ s−1 Like its predecessor, this dam also established a height record in Spain and was a new milestone in our country’s dam engineering The power station was equipped with four Francis power units, with a total power of 56 000 kW (Figure 15)

These two schemes of the Noguera Pallaresa were the beginning, wherever possible, of new way of conceiving hydroelectric exploitation of the rivers by means of their integral exploitation, which included the regulation with dams and reservoirs and steep

Figure 14 Talarn dam and power plant

Figure 15 Camarasa dam and power plant

schemes in large river sections by means of power plants at the base of the dams In rivers with medium flow rates and in winding orography, this solution proved economically competitive in comparison to the classic diversion schemes, which, on the other hand, carried on being viable and were the best solution in many other cases

Integral exploitation studies of basins and rivers began to be carried out from the 1920s The most representative example is the one carried out by José Orbegozo for the exploitation of the lower watercourse of the Duero river and its tributaries in Spain, from the Esla to the Agueda (see Section 6.11.3) The construction of the 97 m-high Ricobayo was finished in 1935, with a reservoir, that exceeded 1000 hm3 and an installed capacity of 133 MW All these numbers were new milestones in Spain’s hydroelectric development

In the western Pyrenees, important projects were also built in the 1920s and 1930s The most important ones had the same scheme: a medium regulation dam and high heads Among these we must mention Lafortunada-Cinca-Pineta, with a 475 m head; Lafortunada-Cinqueta, with a 375 m head; Barrosa-Avellaneda, with a 205 m head; and Urdiceto, with a 426 m head All these jumps were equipped with Pelton turbines

In the Guadalquivir river basin and some of its tributaries, more projects stand out, more due to the characteristics of the dams than for the importance of the power plants That is the case of the Cala power plant, which began being operational in 1927, with a

53 m-high dam, a maximum power of 13 000 kW and a 193 m head One of the most beautiful dams built in Spain was built on the Jándula river in 1932 With a height of 90 m, its aesthetic characteristics are due to its neat plant and the location and design of the hydroelectric power station, which adhered to the downstream wall, anticipating designs that in the future the great André Coyne would use in his Dordogne dams and that would be adopted in the Grandas de Salime and Contreras dams in Spain (Figure 16)

On the Guadalquivir itself and during this period, three projects were built These were Mengibar, El Carpio, and Alcalá del Río,

in 1916, 1922, and 1930, respectively, with head created by barrages (gated dams) in each one The meticulous designs and execution of the plants were a common characteristic of these projects Mengibar was the first gated dam built in Spain (Figure 17) They were all part of the ‘Channelling and exploitation of the Guadalquivir’s power between Córdoba and Seville Project’, and the ambitious project included 11 installations between both cities, each one with a power plant, a lock and a gated dam Finally, navigability was discarded, and from the 11 installations, only four dams with their respective power plants were built

In the Sur river basins, the El Chorro power plant and dam were built on the Guadalhorce river, in an abrupt location ending in

an impressive gorge Soon after, in 1927 the construction of the Gaitanejo dam and power station ended, a little downstream from the previous reservoir It supplied power to the city of Málaga from the time after it began operating The dams were the main elements of both developments: the first, 80 m high with a large regulation reservoir, and the second, of smaller dimensions was

20 m high, and very singular in design, with the power station included in it and the spillway above it (Figure 18)

A-Rejilla protectora B-Compuerta-ataguia plana C-Llave de mariposa D-Llave esférica EyF-Válvulas de cierre de la galeria G-Pozo de equilibrio H-Galeria de comunicacion

Figure 16 Jándula Dam View during construction and cross-section

Figure 17 Mengibar power station and dam

CORTE TRANSVERSAL DE LA PRESA POR EL SECCION TRANSVERSAL POR A-B

EJE DEL SALON DE MAQUINAS Y PROYECCION Y PROYECCION

Figure 18 Gaitanejo dam: Cross-section and photo

Next to the previous one and near the city of Ronda we find the Montejaque dam, which was a 84 m-high first modern arch dam built in Spain It was finished in 1924, and was the top of a hydroelectric scheme which had to be abandoned soon after, as the reservoir could not be filled due to the high leakage through the calcareous basin

6.11.2.3 The 1940–60 Period

6.11.2.3.1 The electricity after the civil war

After the civil war, the situation in Spain was characterized by the economic isolation from abroad, in turn a consequence of two situations that fed each other On the one hand, the international embargo and, on the other hand, the desire of the regime to become a self-sufficient autarchy, aside from the international economy To this we need to add the state of the economy after the physical destruction of industries and facilities, and the disappearance of the emerging industrial infrastructure and, in the first years, the consequences of the Second World War resulting in generalized poverty in Europe

All of this resulted in having to use the same building equipment as that used in the previous decades, a lot of which was in poor condition and needed to be repaired; despite this they carried on using them and achieved good results

During the years of war (1936–39), the energy production capacity stalled, although some power plants continued to be operative, others were damaged or destroyed After this period there was a severe drought, from 1944 to 1946, which resulted in a considerable decrease of hydroelectric production In this way the production capacity excesses of the previous decade turned into important production deficits versus demand, whose growth values in that decade were very high due to the logical reconstruction needs The installed capacity went from 1731 to 2553 MW in the 1940–50 period, due to the new hydroelectric facilities In the

1950–60 period, it rose to 4600 MW In this case from the 2000 MW installed, 1300 belonged to thermal plants, which especially

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The end of the international embargo and a certain economic liberalization gave way to the 1959 Stabilization Plan, which was enforced by the international economic institutions to provide assistance With this assistance, the two development plans established in the following decade allowed for the Spanish economy’s big take off

6.11.2.3.2 Main hydropower developments

As a result of what has been previously mentioned, Spanish hydroelectric development can be considered as a continuation of the previous periods However, this continuation was optimized due to the experience acquired in previous decades and to the Spanish engineers’ know how With few means they were able to build remarkable constructions for that time As an example we must mention Villalcampo, Castro, and Saucelle projects, the second phase of the building of the Duero System, that were put into operation between 1949 and 1956 with capacities of 206, 190, and 240 MW, respectively Those projects were built in difficult execution conditions, both in economic and in technical terms (see Section 6.11.3)

Important hydroelectric systems began to be developed during this period, which in some cases meant the integral exploitation

of basins This is the case of the Sil System, whose first steps were taken during these years and which was completed from 1960 with more complex and advanced installations Between 1952 and 1960, nine power plants were built in it, with seven dams (Figure 19) and a total installed power of around 450 MW, from which more than half corresponded to the power station at the base of the San Esteban dam, with 266 MW

The dams were an important part of these first power plants of the Sil System Seven of them have heights between 22 and 42 m and functions of forebay, with small or medium regulation for diversion schemes The other two are more important, that of San Esteban and that of Chandreja, with relatively small reservoir capacities for height, and whose main purpose is to create height head

in order to locate the power plants at their toe That of San Esteban is a 115 m-high arch-gravity dam, and the most modern means began to be used We could say that it is a transition dam between this period and the next That of Chandreja is an 85 m-high buttress dam This type of dam was used frequently in Spain during that period, due to the lesser need of the scarce concrete and the higher manpower, which were abundant and cheap in those years (Figure 20)

There are numerous power plants and dams of both types from this period in Spain especially with small and medium height dams, and diversion schemes of all types Those located in high plateaus in the Pyrenees stand out This is the case of the Baños power plant, fed by several dams built between 1942 and 1961 in plateaus located between 2100 and 2550 m above sea level, or that of Moncabril, fed by several reservoirs raised by means of dams in glacial lakes in Sanabria (Figure 21) with a net head of 514 m The first important dam in that period was the Grandas de Salime, located on the Navia river in the north of Spain It was built between 1946 and 1955 in abrupt terrain, and is 128 m high, creating an important scheme of 160 MW This dam was a milestone in Spanish dam engineering at that time due to how quickly it was built despite the rather inefficient construction means they had, reaching a European record for daily and weekly concrete laying The location of the power plant stands out, at its base and under

Figure 19 Saltos del Sil diagram, situation in 1961