The world’s most dangerous deserts could be the best places on Earth to harvest solar energy – the most abundant and cleanest source of energy we have. Deserts are spacious, relatively flat, rich in silicon – the raw material for the semiconductors from which solar cells are made – and never run out of sunlight. In reality, the ten largest solar power plants all over the world are all located in deserts or dry regions.
Researchers imagine it might be possible to turn the world’s largest desert, the Sahara, into a giant solar farm, capable of meeting four times current global energy demand. Plans have been developed for projects in Tunisia and Morocco which would supply electricity to millions of homes in Europe.
While the black surfaces of solar panels absorb most of the sunlight that reaches them, only a fraction (around 15%) of that incoming energy gets converted to electricity. The rest is returned to the environment as heat. The panels are usually much darker than the ground they cover, so a vast expanse of solar cells will absorb a lot of additional energy and emit it as heat, affecting the climate.
While the black surfaces of solar panels absorb most of the sunlight that reaches them, only a fraction (about 15%) of this incoming energy is converted into electricity. The rest is returned to the environment as heat. Panels are usually much darker than the ground they cover, so a vast expanse of solar cells will absorb a lot of extra energy and release it as heat, affecting the climate.
It’s still hard to store and transport that much electricity from such a remote place, for one thing, while those people who do live in the Sahara may object to their homeland being transformed into a solar superpower. In any case, turning one particular region into a global energy hub risks all sorts of geopolitical problems.
The Imagine newsletter aims to tackle these big “what if” questions, so we asked a number of academics to weigh in on the challenges of exploiting the cheapest form of electricity from perhaps the cheapest and best spot on Earth.
let me explain. The Saharan sand is unusually light in color, which means it reflects a lot of light and heat back up into the air. On covering the sand in dark solar panels, we would be ensuring that more sunlight is absorbed inducing a rise in the ground temperature. The warmer sand would initiate convection currents to produce rain. The warmer would rise from the desert to high altitudes and condense as clouds. This same moisture there would periodically fall as rain. Before we know it, one of the most extreme climates on Earth would undergo a significant makeover.
So, if these solar panels would not only provide sustainable energy solutions but also add much-needed greenery to our largest desert, then what are we waiting for? Shouldn’t we be out there building these things already? Well, it’s a little more complicated than that. For one thing, it’s great to produce enough energy to power the world, but then you have to worry about how you’re going to get it to everyone. Due to the desert being located far from storage units we would have to most likely take the energy to Europe.
Exporting sustainable energy would do great things for a lot of African economies, but they do not have the means for it. Currently, electrical grids in Africa are under-developed. It would be impossible for them to arrange power lines of around 800–3,000 km (500 to 2,000 miles) to take the energy to Europe Transporting power over long distances leads to power loss of up to 10%, which means that an already expensive project would get even more pricey. On top of that, Northern Africa has historically been a region entrenched in political instability. Such a situation greatly discourages the huge investment needs for this project.
If the desert were a country, it would be fifth biggest in the world – it’s larger than Brazil and slightly smaller than China and the US. Each square meter receives, on average, between 2,000 and 3,000 kilowatt hours of solar energy per year, according to NASA estimates. Given the Sahara covers about 9m km², that means the total energy available – that is, if every inch of the desert soaked up every drop of the sun’s energy – is more than 22 billion gigawatt hours (GWh) a year.
This is again a big number that requires some context: it means that a hypothetical solar farm that covered the entire desert would produce 2,000 times more energy than even the largest power stations in the world, which generate barely 100,000 GWh a year. In fact, its output would be equivalent to more than 36 billion barrels of oil per day – that’s around five barrels per person per day. In this scenario, the Sahara could potentially produce more than 7,000 times the electricity requirements of Europe, with almost no carbon emissions.
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