SDG 7 | Clean and non-polluting energy
Spain currently has around 800 hydroelectric plants, with a very varied range of sizes
Spanish reservoirs have a maximum capacity of 56,136 cubic hectometres, of which 40% of said capacity comes from hydroelectric reservoirs. A percentage that is unrivaled in Europe and the world, being one of the highest. However, the drought that this year hits the Iberian Peninsula, which leaves the swamps at 30% of their capacity throughout Spain, has left many hydroelectric plants in dry dock.
Last year, the production of hydraulic energy, according to data from Red Eléctrica Española (REE), reached 11.9% of the total produced last year in our country. To produce it, it is enough to take advantage of a mass of water located in the riverbed to convert it first into mechanical energy and later into electrical energy.
There are two basic types of hydroelectric exploitation: the flowing one (taking advantage of the course of the river, as traditional waterwheels do) or the dammed one, in which the construction of dams is necessary, this being the main use for electricity generation. Spain currently has nearly 800 hydroelectric plants, with a very varied range of sizes.
“This generation is influenced by the amount of water that is stored and that can be used, as well as the height from which this descent occurs,” explains Rafael Riquelme, of the Official College of Industrial Engineers of Madrid. “The larger these two variables are, the more energy is produced,” he adds.
In 2021, the production of hydraulic energy reached 11.9% of the total, according to data from Red Eléctrica Española
In addition, he considers that one of its main advantages is that “in just two minutes” a hydroelectric plant can be started up to generate energy, compared to the two days that a nuclear plant takes or the long hour that a combined cycle plant can take. .
Adapt to the new scenario
However, hydroelectricity is subject to the availability of that water and with the reservoirs seven percentage points below the average for the previous year and almost twenty points below the ten-year average, hydroelectricity is below its minimum.
This scarcity has brought the first water restrictions for the fields and also towns and has caused a reduction in energy from reservoirs. A drop that reached 52.8% in the month of July 2022 compared to 2021, according to REE data.
But, in order to take better advantage of this natural resource, this industry has devised the construction of new intermediate dams in which to collect the water discharged from the main reservoir to generate energy and upload it back to this upper reservoir for, at the time when appropriate, drop it again and produce energy. This rise in water entails energy use, so it is carried out during the hours when electricity production is cheaper. They are known as pumped or reversible plants.
Spain occupies a prominent role in the hydroelectric area at European level
Of course, it should be noted that Directive 2009/28/EC on the promotion of the use of energy from renewable sources establishes that the electricity produced in pumped storage units that use water that has been pumped upstream should not be considered electricity produced at from renewable sources.
Spain occupies a prominent role in the hydroelectric area at European level, according to the Institute for Energy Diversification and Saving (IDAE), ranking third with respect to the rest of the European Union countries in terms of installed hydroelectric power with smaller plants of 10 MW and fourth place in terms of power plants greater than 10 MW. The Spanish hydroelectric park accounts for 10% of the EU-25 park.
Social and environmental impact
The construction of any dam, in addition to serving to regulate riverbeds, help recover aquifers and promote irrigation in the area, also has other environmental and social impacts, such as the displacement of population groups from flooded valleys to other localities or the loss of much fauna and all the flora of these valleys, which are drowned during the gradual filling process of the dam.
Although from Greenpeace, Julio Barea and Pedro Zorrilla recognize that, as a renewable, hydroelectricity is an energy that, in addition, emits few greenhouse gas emissions in the long term and that the necessary infrastructures “are economically viable if they are done well”. However, they add that they are infrastructures that always modify the river network. “They alter riverbeds, flood valleys and change flows. These are works and projects with a great environmental impact, they completely alter the ecosystem of the river they flood, they represent an insurmountable barrier for fish and other animals that are disconnected from other sections of the river, they store sediments that do not reach the rest of the river or the sea, alter the flow of water throughout the year, solar water at times different from those of the natural and social flow, many times territories used by people are flooded, such as towns, farmland, spaces for cultural and emotional use, which have to abandon them, and they are even forced to abandon their villages and the territories in which they have always lived.
“Our river network is sufficiently punished and that is why we should not build more reservoirs or hydroelectric jumps”
Both ecologists assure that “increasingly, dams that are no longer useful for restoring riparian ecosystems are being demolished. Their usefulness can be evaluated, but as long as they are useful, once they are built, it is difficult to reduce their inconveniences». According to Riquelme, in Spain there is a “tremendously demanding” regulation on environmental impact that makes it difficult to propose new reservoirs. In addition, he considers that the potential of the rivers in our country is also highly exploited, so there is not much prospect of growth in this regard, at least with regard to large dams.
From Greenpeace they consider that with the reservoirs, dams, hydroelectric and mini-hydraulic jumps existing in Spain “our river network is already sufficiently punished, so we should not build more infrastructure of this type, at least conventional.” To this they add that “we will have less and less water available and that the priority of uses is supply and ecological flows, with electricity generation not being a priority in these uses”, so that, in the assessment of this environmental organization, it would be more appropriate to promote other renewable energy.
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