Exploiting the solar energy of the Sahara has been under study for more than 10 years, but a project of such magnitude would not be without consequences. The solar panels in the Sahara would indeed release too much heat into the atmosphere. A Saharan solar farm would thus contribute to global warming. In the long run, researchers say that this could lead to numerous ecological disasters.
Sahara’s solar energy coveted for more than 10 years
David Macklay, precursor of the Solar Sahara project
Exploiting the solar energy of the Sahara is a project that is more than a decade old. The late David MacKay, a renowned British physicist and energy specialist, published the book “Sustainable Energy – without the hot air” in 2008. In this book he stated that “all the power in the world could be provided by a square area of 100 km by 100 km in the Sahara”. In fact, this information opened the door to a giant solar park project, a solar Sahara.
Low population density and high irradiance
The feasibility of Macklay’s theory was then studied by many researchers. Notably, a study was published in 2018 in the journal Science. The International Renewable Energy Agency (IRENA) has also looked into the matter.
This shows that many of the MENA regions (North Africa and the Middle East) have the advantage of low population densities. Moreover, the direct normal irradiance (DNI) is globally high, generally well above the level of 1800/kWh/M2/p.a. Panels in the Sahara would therefore become among the most efficient in the world.
There are currently two technologies for producingsolar electricity in this context. Either concentrated solar power (CSP) or regular solar photovoltaic panels.
The CSP seems to be the most suitable alternative for the field. Due to the direct sunlight, lack of clouds and high temperatures that make it more effective. But the researchers advocate integrating the two technologies to develop a hybrid system.
An exploitation potential of 22 billion GWh/year.
In total, the Sahara covers 9 million m2. It is therefore spacious, relatively flat and rich in silicon: the raw material for the semiconductors from which solar cells are made.
According to IRENA’s 2019 report, the MENA region has seen its total solar energy capacity grow exponentially. It has grown from 40,277 MW in 2010 to 580,159 MW in 2017. This represents an average annual growth rate of 175%.
And according to NASA estimates, each square meter of the Sahara receives between 2000 and 3000 kWh of solar energy per year. The available solar energy of the Sahara is therefore more than 22 billion GWh / year.
According to the 2018 study, once transformed into a solar farm, the Sahara could thus meet four times the current global energy demand. As a result, plans have been drawn up for projects in Tunisia and Morocco.
Unprecedented economic development in the MENA region?
Interconnection and increased energy trade with the MENA region would offer enormous benefits. This includes the opportunity for exporting countries to promote sustainable economic growth and development.
Not only could this stimulate employment, but it would also reduce or improve the situation of regional conflict hotspots.
In this sense, the pan-Arab strategy adopted in 2019 establishes a solid basis for regional cooperation. To stimulate futuresolar energy deployment, the region is committed to increasing installed renewable energy generation capacity. The goal is to reach 80 GW by 2030.
But there are other constraints to eventually supplying energy from solar panels in the Sahara to the rest of the world. Many efforts are indeed necessary, mainly in the fields of energy storage and transport. Worse still, a Solar Sahara would greatly disturb the climate, to the point of changing the nature of this biotope.
Exploiting Saharan solar energy would accelerate global warming
Solarizing the Sahara could turn it into an oasis
One of the hypothetical effects of a massive solar farm in the Sahara is to see the desert turn into an oasis. To that end, in the 2018 study, researchers created a climate model to simulate the effects of albedo (reflectivity of a surface) on the land surface of deserts.
Thus, naturally the solar panels are darker than the ground. In fact, if a solar farm covered even 20% of the entire Sahara, it would trigger a feedback loop.
The emitted heat would create a steep temperature difference between the land and the surrounding oceans. This would lower the air pressure at the surface and condense the moist air into raindrops. The Saharan environment would become more humid and would see its vegetation expand rapidly. In short, some kind of oasis would take place on these formerly arid and barren lands.
Solarizing the Sahara could warm the glaciers
Although it sounds promising, harnessing the Sahara’s solar energy would contribute to global warming. Covering 20% of the Sahara would then increase local temperatures by 1.5°C. A 50% coverage would increase the temperature by 2.5°C.
However, the global temperature change is not uniform. As the polar regions warm more than the tropics, this would also increase ice melt in the Arctic. The snowball effect would then accelerate warming. In this sense, melting sea ice exposes subglacial water at the surface. This water being black, it absorbs a lot of heat.
Solarizing the Sahara could dry up the Amazon
This massive new heat source in the Sahara would also reorganize global air and ocean circulation. And this, by affecting precipitation patterns worldwide.
Among the effects cited in studies on the subject, we find drought in the Amazon. Due to less moisture from the ocean.
The model in the Science study also predicts more frequent tropical cyclones hitting the North American and East Asian coasts.
Finally, too much usable heat
In general, only 15 to 20% of the incoming solar energy on a given absorbing surface (solar panels) can be harnessed and converted into electricity. The rest returns to the environment as heat.
If all these exposed effects were only localized, their significance would be relatively covered by the natural balance. On the other hand, a complete answer to the current world energy needs could not be satisfied with only localized solar installations. Therefore, this would, according to the studies presented, accelerate global warming.