Should we turn the Sahara desert into a huge solar power station?

Every time I visit the Sahara, I am amazed at how hot and sunny it is and how clear the sky can be. Apart from a few oases, vegetation is scarce and most of the world's desert is covered with rocks, sand and dunes. The Saharan sun is intense enough to provide the Earth with considerable solar energy.

The statistics are incredible. If the desert was 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 between 2,000 and 3,000 kilowatt hours of solar energy per year. As the Sahara covers an area of ​​about 9 million km², it means that the total energy available, that is if every inch of the desert absorbs every drop of solar energy , raises to over 22,000 million gigawatt hours (GwH). per year.

This is a figure that requires context: it means that a hypothetical solar park covering the entire desert would produce 2,000 times more energy than the largest power plants in the world, producing only 100,000 GWh per year. In fact, production would be more than 36 billion barrels of oil a day, or about five barrels per person per day. In this scenario, the Sahara could potentially produce more than seven times Europe's electricity needs, with virtually no carbon emissions.

In addition, the Sahara also has the advantage of being very close to Europe. The shortest distance between North Africa and Europe is only 15 km in the Strait of Gibraltar. But, even if the distance was greater, across most of the Mediterranean, it would also be possible to transport energy. After all, the largest submarine cable in the world travels about 600 km between Norway and the Netherlands.

Over the last decade, scientists (including my colleagues and myself) have been studying how solar energy from the desert could meet the growing demand for local energy and, finally, supply Europe as well. than its operation in practice. And these academic ideas have come to fruition in rigorous plans.

The main attempt was Desertec, a project announced in 2009 that quickly allowed several banks and energy companies to acquire significant funds, before collapsing when most investors withdrew five years later, mentioning high costs. These projects are hampered by a range of political, commercial and social factors, including the lack of development in the region.

Among the most recent proposals are the TuNur project in Tunisia, which aims to provide energy to more than 2 million European households, or the Noor Complex solar power plant in Morocco, which also plans to export energy to Morocco. energy in Europe.

There are currently two specific technologies for the production of solar electricity in this context: Concentrated Solar Energy (CSP) and conventional solar photovoltaic panels. Each has its advantages and disadvantages.

Concentrated solar energy uses lenses or mirrors to focus the sun's energy into 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 produces electricity at night.

The CSP seems to be the most suitable for the Sahara because of the direct sunlight, lack of clouds and high temperatures, which makes it much more efficient. However, lenses and mirrors could be covered by sandstorms and turbine and steam heating systems remain complex technologies. But the major disadvantage of this technology is that it would use scarce hydraulic resources in the desert.

Solar photovoltaic panels, on the other hand, convert the sun's energy into electricity by directly using semiconductors. This is the most common type of solar energy because it can be connected to the grid or distributed for small scale use in individual buildings. In addition, it offers reasonable performance when the sky is cloudy.

But one of its disadvantages is that when 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. Do not forget that the demand for energy for air conditioning is more important during the hottest hours of the day. Another problem is that sandstorms could cover the panels, which would further reduce their effectiveness.

Both technologies require a certain amount of water to clean mirrors and panels, making water an important factor to consider. Most researchers suggest integrating both technologies and developing a hybrid system.

A small part of the Sahara could produce as much energy as that 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.
Amin Al-Habaibeh: Professor of Intelligent Engineering Systems, University of Nottingham Trent

Article translated with the collaboration of Casa África by Daniela Magdaleno and Eduardo Puche.