Whenever I visit the Sahara, it surprises me how sunny and hot it is, and how clear the sky can be. Apart from a few cases, there is little vegetation, and most of the largest desert in the world is covered with rocks, sand, and dunes. The Saharan sun is quite intense to provide the Earth with considerable solar energy.
The statistics are amazing. If the desert were a country, it could be the fifth largest in the world; it is bigger than Brazil and slightly smaller than China and the United States.
According to NASA estimates, each square meter receives, on average, between 2,000 and 3,000-kilowatt hours of solar energy per year.
Since the Sahara has an area of about nine million square kilometers, this means that the total available energy - that is, if every centimeter of the desert absorbs every drop of solar energy - is more than 22,000 million gigawatt hours (GWh ) year.
Solar park
This is a figure that requires context: it means that a hypothetical solar park that covers the entire desert would produce 2,000 times more energy than the largest power plants in the world, which only generate 100,000 GWh per year.
In addition, Sahara also has the advantage of being very close to Europe. The shortest distance between North Africa and Europe is only 14.4 kilometers in the Strait of Gibraltar.
But, even if the distance were greater, through the widest part of the Mediterranean, it would also be possible to transport energy. After all, the largest submarine cable in the world travels about 600 kilometers between Norway and the Netherlands.
Over the past decade, scientists (including my colleagues and I ) have investigated how desert solar energy could meet the growing local demand for energy, and finally, supply Europe as well, and how it could work in practice. And these academic ideas have materialized in rigorous plans.
Desertec
The main attempt was Desertec, a project announced in 2009 that quickly acquired a significant amount of funds from several banks and energy companies before collapsing when most investors withdrew five years later, citing high costs.These projects are held back by a series of political, commercial and social factors, including the lack of development in the region.
Among the most recent proposals is the TuNur project in Tunisia, which aims to supply energy to more than two million European households, or the Noor Complex solar power plant in Morocco, which also intends to export energy to Europe.
At present, there are two specific technologies for the generation of solar electricity in this context: solar energy by concentration (CSP) and conventional photovoltaic solar panels. Each has its advantages and disadvantages.
Concentrated solar
Concentrated solar energy uses lenses or mirrors to focus the sun's energy at a single point, which becomes very hot. This heat generates electricity through conventional steam turbines. Some systems use molten salt to store energy, which also allows electricity to be produced at night.
The CSP seems to be the most suitable for the Sahara due to direct sunlight, lack of clouds and high temperatures, which makes it much more efficient.
However, lenses and mirrors could be covered by sandstorms, and the turbine and steam heating systems remain complex technologies. But the most important drawback of this technology is that it would make use of hydraulic resources that are scarce in the desert.
Solar photovoltaic
Photovoltaic solar panels, on the other hand, convert the energy of the sun into electricity using directly semiconductors. It is the most common type of solar energy since it can be connected to the electricity grid or distributed for small-scale use in individual buildings. In addition, it provides reasonable performance when the sky is cloudy.But one of its disadvantages is that when the panels get too hot their efficiency decreases. This is not recommended in a part of the world where summer temperatures can easily exceed 45 ° C in the shade.
Keep in mind that the demand for energy for air conditioning is higher during the hottest hours of the day. Another problem is that sandstorms could cover the panels, further reducing their efficiency.
Both technologies need a certain amount of water to clean the mirrors and panels, which makes water an important factor to consider. Most researchers suggest integrating the two technologies and developing a hybrid system.
A small part of the Sahara could produce as much energy as the one currently produced by the entire African continent. As solar technology improves, production will be cheaper and more efficient. The Sahara can be inhospitable to most plants and animals, but it could produce sustainable energy to keep all of North Africa and beyond alive.
