DESERTEC and the dream of a Solar Sahara — podcast script edition

Author’s note: This podcast script is an adapted version of an article I first published for Singularity Hub in 2017. The podcast version was finally published in late November 2020.

There is a rule of thumb. It doesn’t always work — sometimes we are lucky enough not to need to apply it — but it generally works pretty well. The rule is: “If someone offers you a simple solution to a complex problem, it probably doesn’t work.” Either they haven’t thought through the problem enough, or they don’t want you to think through the problem enough, and the reasoning behind that is unlikely to be to your benefit. There is a massive industry of people out there who want to sell you the idea that complicated problems — in your personal life, or in the world at large — have a simple solution; and it’s tantalizing to think that they do, even when evidence cuts against it.

With all that said, the entire energy demand — not just electricity, but energy demand of the world, which is usually 7 or 8 times higher — could be met by covering a small fraction, perhaps 1%, of the Sahara desert in solar panels. Sure, it would be a big project — but once complete, humanity would no longer depend on finite fossil fuels for energy. If you squint, it seems like this is the solution to all of our energy and climate problems.

The story behind how this idea first came about is quite a good one, so I’ll repeat it here.

In 1986, a power surge during a safety test of the reactor at Chernobyl caused a catastrophic explosion. Thirty-one people were directly killed by the explosion and the initial dose of radiation, and many more may have died due to the lasting effects of the fallout. Alongside the Fukushima event in 2011, it is one of only two nuclear power disasters to be rated as a maximum severity event, ominously referred to as level 7. All over the world, support for nuclear power plummeted. But in Germany, Gerhard Knies — a particle physicist — was inspired to ask a simple question. Fossil fuels such as coal, oil, and natural gas: their energy flowed from the Sun. It took a torturous path through plants and animals that were buried for thousands of years to get to us. The radioactive Uranium that fuelled nuclear power plants was also forged as a trace by-product of nuclear fusion in stars. Would it not be easier, cheaper, and cleaner to get our energy directly from the Sun?

Knies did a simple back-of-the-envelope calculation and worked out that, in just six hours, the world’s deserts receive more solar energy than the entire human race consumes in a year. The energy needs of the world could be met by covering just 1.2% of the Sahara desert in solar panels. The Sahara gets an awful lot of energy from the Sun, which is likely obvious if you’ve ever been there, and much of it is uninhabited. Knies likely wasn’t even thinking about carbon emissions — just the fact that fossil fuels would one day run out — but climate change provides an even more stark motivation for pursuing the project. And, of course, it just seems so simple: Knies himself was frustrated about it, questioning “Are we, as a species, really so stupid as to not make a better use of this resource?”

While we’re in this fantasy world, let’s make some very, very loose estimates that will give us a slightly better idea as to how the mathematics of such a project might really work out. This 1.2% estimate, after all, makes a lot of assumptions — mostly to do with how easily you can harness energy and how closely together solar panels are spaced.




Global energy consumption is around 100,000TWh/year, give or take a hundred thousand. The Pavagada Solar Park in India is a true monster, covering 53 square kilometers, with a capacity of around 2GW — it’s the second largest solar power plant in the world, built in an arid region in India that was sparsely populated before.

When it comes to any power plant, they’re never running at that maximum capacity. To account for this, we have the capacity factor, which is approximately the average fraction of that capacity that is generating across the year. It’s hard to estimate because capacity factors are difficult to calculate — they depend on the weather, the daily and seasonal cycles, and so forth. Some estimates suggest capacity factors for solar farms in India are between 11 and 30%, so let’s take 20% as a rough rule of thumb. This then means that the Pavagada Solar Park is generating around 3.5TWh/yr.

So if we assume all solar farms are exactly like this, and ignore for a second the massive issue of storing electricity to cover periods of low generation, and transmitting it to where it is needed etc — then we see that we need around 30,000 such solar farms to cover global energy demand. They, in turn, would cover around 1.6 million square kilometers. The Sahara Desert is about 9.2 million square kilometers, so simply by using the statistics from an actual solar farm, you can see that the 1.2% figure might end up being 20% or so of the desert. And yeah, you can have more efficient panels, and you can push them closer together, but this is unlikely to get you 10x as many panels in — we’re talking factors 2 or 3 with that type of improvement.

This is very reminiscent of a conclusion that the late, great David Mackay wrote about in Sustainable Energy Without the Hot Air — which is essentially one of the key drawbacks of renewables; the amount of space that they take up. If you were able to blanket the UK in solar panels to the same specification as those in the Pavagada Park, you would need to cover 15–30% of the entire surface area of the country in those panels to supply our energy needs. In other words, you need to plan for renewables that are significant in scale and take up a lot of space. Mackay pointed out that for some countries — those with low populations and a lot of empty space; for example, any country containing a massive desert; this will be more realisable than others. If you want your numbers to add up, then supplying the UK’s energy demand with 100% renewables is going to require you to manage this space very carefully. The UK has done very well by exploiting our seas — for example, the North Sea — and building huge amounts of offshore wind farms, which supply something like half of our electricity demand. But, as I mentioned, the total energy demand, which includes heating for domestic industry and transport, is often 6–7 times as high. Ultimately, unless you expect everything to be done by biofuels, you need to electrify everything and have all of that electricity supplied renewably — so you’re back to needing renewables on a truly massive scale. This is why, for the UK specifically, which has a pretty small solar resource, an incredibly dense and energy-intensive population, and a very small land area, he recommended either nuclear power on our shores — which I personally still think will end up being both necessary and the cheapest option for at least a significant fraction of our energy demand — or getting our renewable electricity through a big interconnector system with other countries; perhaps some of those countries with large deserts that have excess power. And we’re back once again to the dream of a solar Sahara.

How much would it cost? Again, we can — very, very naively and roughly get an estimate for the raw cost of building such a plant. The Pavagada plant cost $2bn to construct, so naively multiplying this by the 30,000 we’d need and you have a “mere” $60trn. Now, of course, if you were building enough solar panels and a large enough farm to cover a vast swathe of the Sahara in the greatest engineering project ever accomplished by humanity, and throwing trillions of dollars behind your efforts, you imagine that there would be some pretty awesome technological innovations and economies of scale to reduce that cost substantially below that inflated figure. Let’s say we can cut it down to $15trn or so. Sounds like an awful lot, but the global financial markets wiped that much off during the 2008–9 financial crisis in the course of a year or so. If this project was built over, say, ten or fifteen years, it would “only” be around $1.5trn a year, or a mere % of global GDP. And this would hardly be money that was LOST, as it was in the global financial crisis, but instead investment in humanity’s future, producing a colossal amount of jobs and economic booms in solar panel manufacturing and installation.

Clearly we are fantasising here and not even taking this prospect particularly seriously when we do this kind of silly back-of-the-envelope calculation. We might all have fantasies of playing dictator — snapping our fingers, saying “make it so!” and establishing the proper order of things, but we know that this can’t happen. Except, of course, that some people have taken it seriously indeed.

Of course, it is difficult to persuade people to invest in such a grand and ambitious scheme — and one that requires an awful lot of overhead investment before realizing any profit — but the DESERTEC initiative was a real attempt to demonstrate that the concept could work. The plan was to put solar panels in the Sahara that would power a great deal of the Middle East and North African (MENA) energy needs, while also allowing for a valuable (€60bn) energy export industry that would power 15% of Europe’s electricity requirements. Meanwhile, the Europeans — by importing the plentiful desert power — would save €30/MWh on their electricity bills. Everyone would win — in the long run.

The Desertec project began in earnest in 2009, and quickly had a number of industry partners lined up1, including EON, DeutscheBank, and Siemens. Their investment would be necessary, as the project was estimated to cost €400bn — although, unlike, for example, a giant wall across the US-Mexico border, it had a prayer of paying for itself after some years of operation. But the project stalled, and, by 2014, the 17 initial industry partners who had signed up had dwindled to just three.

So what went wrong with Desertec? A combination of two different sets of factors. The first are the issues that have plagued the transition to renewable energy for decades now. The second are the unique geopolitical and logistical challenges of solar-panels-in-the-Sahara more specifically. Both are worth looking into.

First, the general issues with renewable energy. The DESERTEC plan called for a centralized power station that would deliver electricity across three continents, and transporting that electricity across such long distances can be a problem. The plan was to use high voltage DC power-lines — rather than the AC power lines that we’re familiar with. Across longer distances, the energy losses can be as little as 3% per 1,000km, which is much lower than AC power lines. But nothing had ever been built on that scale before; the longest link is in Brazil, the Rio Madeira line, and transports 6.3GW across around 2,400km. For DESERTEC to be a success, 30GW of power would need to be transported from the Sahara to Europe — more than 3000km. Yet this may seem more feasible with the news in July 2016 that the Chinese are funding a HVDC power line that will transport 12GW across 3,000km. In just the last five years, it has become fairly routine for gigawatts of power to be transported across China through ultra high-voltage for a thousand km or more — which is done largely to transmit power from China’s huge electricity facilities to the cities. So this is an engineering option, even if it’s likely to be expensive.
Speaking of which — although we are focusing on the solar Sahara as symbolic of how this kind of approach might work, it’s pretty obvious that you wouldn’t supply the entire world’s energy from the Sahara alone. Instead, you’d put similar large-scale installations in any given desert for any given region — in China, that might be the domestic desert landscapes; in other places, you can match your own regional desert to the appropriate large population centre. As David Mackay showed, you can imagine putting similar patches to supply most of the continents of the world with energy in such a way that doesn’t require power to be transported across truly ridiculous distances, if you want. In reality, of course, we’d expect people to try to find the lowest-cost option — when the cost of transmitting and storing electricity becomes more dominant than the abundant, cheap electricity you might get from building a huge solar farm in a desert, you can expect that to limit the scale of the farm that gets built.

It’s not just about transporting the power. A major issue with renewables is the intermittency problem; what do you do when the Sun doesn’t shine? Energy industry researchers talk about a hypothesized “European super-grid” that allows for the transmission of power from regions of excess production to regions of excess need. The same thing happens internally in countries to ensure a constant supply of electricity, but they have the advantage of depending on fossil fuel plants where the energy production can be ramped up or down at will. There are precedents for this kind of system: France and the UK are connected by a 2GW power line. HVDC allows power to be sent in both directions, depending on demand; usually, the British import French electricity, but not always. The fjords of Norway allow them to produce 98% of their electricity in hydroelectric plants; the winds of Denmark allow them to produce 50% of their electricity by renewables; and cables across Scandinavia ensure that everyone can obtain power whether the wind’s blowing or the sun is shining. Studies have indicated that the Mediterranean, with better interconnectivity and a source of power like DESERTEC, could supply 80% of its electricity needs by solar alone without worrying about intermittency.

Yet it seems likely that weaning the grid off the convenience of fossil fuels entirely will need a combination of policies. First, diversified renewable sources of energy, including plenty of power that can be ‘turned on’ to cope with surges in demand; or else a lot of latent, extra capacity. Secondly, energy storage technologies that will prevent waste and allow for a continuous supply. But energy storage is still, really, in its infancy. Our best method in terms of what has been implemented on a wide scale is pumped storage hydroelectric power; during times of excess supply, water is pumped uphill, and during excess demand, it’s allowed to run downhill and drive a turbine.

This one technique accounts for 99% of global storage capacity, which is a respectable 127GW. But that pales in comparison to the 15TW of power used globally. If all the energy storage capacity we have was deployed at the same time, it would provide less than 1% of the power we use. There are plenty of ideas for improving this. We could charge up supercapacitors with excess electricity and allow them to discharge later. We could use the electricity to electrolyse water, converting it into hydrogen which can be burned in fuel cells (producing only water as a by-product). People are even looking into converting the electrical energy into a store of gravitational potential energy by lifting rocks. Sisyphus, all is forgiven.

As yet, none of these energy-storage mechanisms has demonstrated that it can be scaled up to the levels that would be required. But for Desertec, there were more specific problems. For a start, as people were looking into the project to centre the world’s power supply in Libya and Algeria… there was a civil war in Libya, and although the Arab Spring initially boosted hopes for the plan, the continuing political instability in the Sahara has spooked some investors. Combine that with the fact that the project was never intended to be finished until 2050, and industrial partners would have to be persuaded away from more near-term opportunities for profit.

Then there is the more delicate political issue of natural resource rights. Like many bold, futuristic projects, the little matter of governments can get in the way of something like DESERTEC. Countries have been made rich through exports of oil, or coal; could sunlight one day fulfil a similar role? On the surface, this is another bonus to the DESERTEC scheme; poorer countries in Africa have something incredibly valuable to export to the rest of the world, while amply supplying their own energy needs. In practice, there has been scepticism on the ground that this isn’t just another imperialist exploitation move: such as via Daniel Ayuk Mbi Egbe of the African Network for Solar Energy. ‘Europeans make promises, but at the end of the day, they bring their engineers, they bring their equipment, and they go. It’s a new form of resource exploitation, just like in the past.’

There is another, slightly more hopeful reason that DESERTEC has stalled. It backed CSP — concentrated solar power — where parabolic mirrors concentrate sunlight, which boils steam to drive wind turbines. This was the technology that brought Siemens on board. The only problem is that, as DESERTEC was being developed, the price of solar panels (solar photovoltaics) fell off a cliff. From 2009 to 2014, the Levelized Cost of Electricity (taking into account construction, maintenance, fuel etc.) of solar PV fell by 78%, and it’s still going down. In just five years, PV became five times cheaper. This was one of the reasons Siemens cited for abandoning the project.

DESERTEC continues in a smaller form; they’re still building power plants in Morocco to supply the local energy needs of that country. Perhaps a ground-up approach, where MENA countries increase their own solar production in the desert before becoming net exporters, will provide the solution in the long term. And there is, of course, a certain justice and convenience to this. Countries that currently depend on fossil fuel exports also quite often happen to have large areas which could be devoted to solar power. Countries that have historically been disadvantaged are abundant in this natural resource. So, if these inter-connectors end up being built, there’s a possibility that these nations can continue to supply the densely-populated, cold and dark Northern hemisphere with power for their winters… for a price.

This project is not the first wildly ambitious scheme to provide for the world’s energy needs that has stalled; historians remember Atlantropa, a scheme to dam the Strait of Gibraltar and use it for hydroelectric power that had some interest in the 1920s. This was actually a pretty wild idea, even for someone who documents the history of wild ideas. The concept — dam across the Strait of Gibraltar which seperates Spain from Africa, and that dam would become a massive hydroelectric power plant that would power Europe and Africa with power. The Mediterranean Sea would be trapped in the middle — so they would desalinate the water to irrigate massive areas of agricultural land that would be reclaimed from under the ocean, as well as providing water. It was really a planetary engineering project out of science fiction… which is partly why it attracted the interest of the Nazis briefly. As with DESERTEC, there are worrying colonial implications to this project, which would really be something that was imposed on nations in Africa and the Middle East to supply excess import demand for power, land, and food in Europe. It was even, briefly, popularised as an idea to rebuild after the Second World War by some of the Western Allies, who recognised that the massive economic stimulus associated with such a project, alongside the consolidation of influence over Africa — already increasingly a battleground in the Cold War by then — would be strategically useful. But it was ultimately abandoned largely with the death of its inventor and main proponent, and hasn’t been seriously considered since 1960.

Yet despite all this, the prospect that we could solve all of our problems with such a massive engineering project remains tantalizing. It’s not totally different, after all, to a planet-wide Green New Deal — and, in the most idealistic case, could even encourage people and nations to cooperate for once. Surely, when only a tiny fraction of the Earth’s surface need be devoted to energy production to provide us with more power than we could ever dream of consuming, we won’t wreck the planet by getting that energy through dirty and dangerous means. To starry-eyed idealists, it must seem equivalent to being on a raft in a lake full of drinking water — and choosing instead to swig from a bottle of seawater in your backpack. In reality, dreams of actually turning that tiny patch of map into the world’s energy hub are idealistic and oversimplified. But you still feel one thing is true:

Someday, we will make better use of the abundant energy from the Sun. We’ll have to.

1 https://newint.org/features/2015/03/01/desertec-long