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The eternal energetic power
Algeria
There is still time to do well, everything is there. From Béchar to Biskra via Laghouat on the southern slope of the Saharan Atlas, a vast region of underground water extends, extending to the extreme South, to the limit of Reggane, In-Salah, In -Amenas and spanning a good part of Libya and southern Tunisia.
Water stored in the bowels of the earth for millions of years The word Sahara evokes desert expanses, poor in water and arid, due to the fact that it is little watered, by low rainfall, including sheets of water surface are rare. In fact, the Northern Sahara aquifer, which extends over more than a million square kilometers under Algeria, Tunisia and Libya, contains approximately 31,000 billion cubic meters of water, 2/3 of which are found in Algeria. More than 20,000 billion cubic meters are locked within Algerian borders. By a simple empirical calculation based on an annual consumption of 10 billion cubic meters per year, our water needs will be covered over 2,000 years.
According to the French researcher in underground hydraulics, Jean Margat, the aquifers of the northern Sahara are a fossil reservoir. It was formed more than 10,000 years ago, when the region was subject to a more humid climate. For tens of thousands of years, rain has infiltrated the subsoil and accumulated in different geological layers. This is how the two main reserves of the aquifer were formed: the “intercalary continental”, the deepest and largest, and the terminal complex, he says?
The first extends several hundred meters deep (its roof is between 50 and 2,300 meters below the surface depending on the location) over 600,000 square kilometers in sandstones and clays 100 to 150 million years old. Around 20,000 billion cubic meters of water are trapped in this first layer. Above, the sands and limestones of the terminal complex, formed 30 to 80 million years ago, contain an additional 11,000 billion cubic meters in the second layer, for a total of 31,000 billion cubic meters.
According to Mr. Abdelmalek Sellal, former Minister of Water Resources who declared during a visit to Orania, that these drinking water reserves of the Sahara are estimated, according to recent studies, at 40,000 billion cubic meters, while confirming the figure of 20,000 billion cubic meters announced by Mr. Jean Margat. In short, it is this important confirmation that interests us, in order to be able to think about valorizing this resource in the near future and at an opportune moment when the former Minister of Energy and Mines Youcef Youcefi is looking for other energy resources substituting for oil.
With the help of solar energy in great abundance in the Sahara from which we can extract an unlimited quantity of electricity for the continuity of our social and economic development. Using large diameter pipes, the water drawn from the water table is pumped by gigantic pumps to the dams built on the hills. From these dams the water will flow by gravity to operate hydraulic turbines in order to produce electricity and at the same time irrigate immense plains developed at low altitude, with this water after its use. There you have it, enviable projects that we should have thought of a long time ago?
Aware of the fragility of the system and the cross-border problems that will arise, Algeria, Tunisia and Libya have established a cross-border management and surveillance mechanism, which works very poorly. More than 11,000 wells have been drilled and no less than 2.5 billion cubic meters of water are pumped wildly annually by Libya and Tunisia. Responsibility lies with the Sahara and Sahel Observatory (OSS), an international organization working in the fight against desertification and poverty in Africa.
Based in Tunis, this observatory is supposed to manage the behavior of the aquifer and to ration the exploitation of this wealth. We wonder why this Observatory is installed in Tunisia, and why not in Algeria or southern Algeria given that the subsoil of our Sahara contains 2/3 of this wealth?
The objective of this laboratory was to collect measurements made at the level of boreholes and wells (level height, quantity of water pumped, salt content, etc.), integrate them into a digital model simulating the evolution of the aquifer in order to monitor withdrawals in real time and to issue possible alerts in the event of pumping. This work seems very insufficient to us, for the constitution of a primary file for a possible need, in which Algerian officials decide to seriously highlight this enormous economic potential.
In 1984, Libya launched an ambitious project to create a large artificial river to transport water from this deposit to the northern regions without the knowledge of its neighbors Algeria and Tunisia. The rate of extraction is anarchic, it is currently so high that, in less than fifty years, Libya will have to divide its groundwater supplies by ten, experts warn. As we will see, the Algerian part is delimited by an anticline flush with the surface of the ground, creating a natural limit to preserve our water. In the event of excessive pumping by Libya and/or Tunisia, the Algerian side is naturally protected against pillaging unless the physics of groundwater flows holds any surprises for us?
THE SUN
Solar collectors on one-twentieth of the Sahara’s surface would provide enough electricity to supply the entire world. The problem is being able to export this clean energy at a reasonable cost.
In the quest and search for new sources of sustainable and renewable energy as a source of replacement for disappearing fossil fuels, and in order to satisfy our energy future, all avenues are exploreable; the sky, the earth and the sea have become spaces for reflection around energy recovery. Ideas are flourishing almost everywhere due to the “hidden” decline of our oil and gas reserves: shale gas, Kénadza coal, construction of solar power plants, etc. Among all this range of recourses, the most durable and the most favorite energy is solar.
Fields of cylindrical-parabolic solar collectors installed on 1/20th of the surface of the Sahara would be sufficient to cover global electricity consumption which is approximately 18,000 Twh/year (18,000,000 Gwh/year) as an example. ‘Algeria produces 10 TWh/year from its flame-fired power plants (running on natural gas), a waste for our oil economy. The Sahara covers 1.5 million square km; an area of 30 square km, planted with solar panels, would be enough to satisfy national electricity consumption. Hence a great saving in natural gas, diesel and non-conventional gas in the event that the latter emerges safely from its controversy.
So, again if the Algerian State manages to adopt electricity as a “national fuel”, we will save the import of 42 million tonnes/year at a high price in foreign currency or by the “barter” of an equivalent quantity of gas from shale, as predicted by our Minister of Energy. A false calculation that is based only on assumptions?
The “DESERTEC” plan
TREC (Trans-Mediterranean Renewable Energy Cooperation), in collaboration with the German Aerospace Center (DLR) carried out the study of the “DESERTEC Project” with the aim of evaluating the feasibility of a concept aimed at producing electricity and fresh water using concentrated solar power plants located in the Sahara. The idea is to produce fresh water by seawater desalination processes (by distillation or reverse osmosis) which use part of the electricity or heat produced by the solar installation.
The project aims, on the one hand, to provide development prospects for these Sahara countries and on the other hand to export part of the electricity produced to satisfy European demand for green energy. As is often the case, the cost of such a project is the main obstacle to its accomplishment. The transport of electricity over long distances will have to be done using high voltage direct current but the cost of this technology remains very high… Except for Algeria where the outlets are on site, its electricity needs by 2020 will be of the order of 22,000 MW, the equivalent of 22 power plants of the type installed in Tilghemt (Hassi-R’mel). The price of the KW of electricity produced will be the lowest compared to our neighbors, given that there would be a hybrid coupling, using natural gas during off-peak hours when sunshine is at a minimum, something that our neighbors do not ‘have no other way to do so much. The hybrid process is a combination of processes relayed to continuously produce electricity from a hot source and from solar power. It is quite remarkable that this production model falls within the perfect framework of security of energy supplies.
For Algeria, the “Désertec” project cannot be discussed without taking charge of the exploitation of the Sahara aquifer and its specific needs in solar electricity. Also, the distribution in number of solar power plants between neighboring countries (Algeria, Morocco, Tunisia, Libya) must be equitable, in order to avoid any unjustifiable controversy, which could lead to conflicts between neighbors. Algeria will need many more power plants than its neighbors, in order to meet its growing needs for electrical energy, necessary for its sustainable development. It will therefore need much more electrical energy for the large-scale exploitation of this water table, which undeniably falls within the framework of Nepad, for the development of Africa.
Conclusion
The Algerian Sahara presents real oases of energy due to strong direct sunshine, it is the sunniest country in the world in terms of number of days and almost permanent (3,000-3,500 hours of sunshine per year compared to 1,500 hours in Paris). On the other hand, solar technologies – photovoltaic and concentrated solar power – have today reached sufficient maturity to consider the deployment of large solar farms on the sites listed as being the most favorable.
By Youcef Mérabet
State engineer in petroleum engineering