Turning the Sahara Desert into a giant solar farm could power Europe 7,000 times over. But how would we keep the panels clear of sand?
If the Sahara desert were a country, it would be fifth biggest in the world – it’s larger than Brazil and only slightly smaller than China and the US, covering nine million square kilometres. Aside from a few oases, there is little vegetation. It’s rocks and sand that are soaking up the sun. What if the world’s largest desert were covered with solar panels instead?
Each square metre receives, on average, between 2,000 and 3,000 kilowatt hours of solar energy per year, according to NASA estimates.
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 hypothetical solar farm would produce 2,000 times more energy than even the largest power stations in the world – such as the Three Gorges Dam in China, or the Itaipu Dam between Brazil and Paraguay, which generate about 100,000 GWh a year. The UK’s largest solar farm, Shotwick in north Wales, has a peak capacity of just 92 MW.
In fact, the Sahara could potentially produce more than 7,000 times the electricity requirements of Europe, with almost no carbon emissions – showing that even making use of just a fraction of this desert land could revolutionise the way we generate and use energy.
The Sahara also has the advantage of being very close to Europe. The shortest distance between North Africa and Europe is just nine miles at the Strait of Gibraltar. But even much further distances, across the Mediterranean, are perfectly practical – after all, the world’s longest underwater power cable runs for nearly 375 miles between Norway and the Netherlands.
Over the past decade or so, scientists have looked at how desert solar could meet increasing local energy demand and eventually power Europe too, and how this might work in practice.
The most high-profile attempt was Desertec, a scheme announced in 2009 that quickly acquired lots of funding from various banks and energy firms, aiming to generate 100GW by 2050 at a cost of €400bn (2340bn). It largely collapsed five years later when most investors pulled out, citing high costs. Political, commercial and social factors can all be obstacles.
More recent proposals include the TuNur project in Tunisia, which aims to power more than two million European homes, or the Noor Complex Solar Power Plant in Morocco, which also hopes to export energy to Europe.
So far there are two practical technologies that can generate solar electricity for projects like these: concentrated solar power (CSP) and regular photovoltaic solar panels. Each has its pros and cons.
CSP uses lenses or mirrors to focus the sun’s energy in one spot, which becomes incredibly hot. This heat then generates electricity through conventional steam turbines. Some systems use molten salt to store energy, allowing electricity to also be produced at night.
CSP seems to be more suitable to the Sahara due to the direct sun, lack of clouds and high temperatures which makes it more efficient. However, the lenses and mirrors could be covered by sand storms, while the turbine and steam heating systems remain complex technologies. But the most important drawback of the technology is its use of scarce water resources.
Photovoltaic solar panels instead convert the sun’s energy to electricity directly, using semiconductors. This is the most common type of solar power as it can be either connected to the grid or distributed for small-scale use on individual buildings. Also, it provides reasonable output in cloudy weather.
One of the drawbacks is that when the panels get too hot their efficiency drops. This isn’t ideal in a part of the world where summer temperatures can easily exceed 45°C in the shade, and given that demand for energy to power air conditioning is strongest during the hottest parts of the day.
There also remains the problem that sand storms could cover the panels, further reducing their efficiency. Both technologies are likely to need some amount of water to clean the mirrors and panels depending on the weather.
Most researchers suggest integrating the two main technologies to develop a hybrid system. Just a small portion of the Sahara could produce as much energy as the entire continent of Africa does at present. As solar technology improves, things will only get cheaper and more efficient. The Sahara may be inhospitable for most plants and animals, but it could bring sustainable energy to life across North Africa – and beyond. (Amin At-Habaibeh)