The word sand usually conjures up images of a holiday on the beach. But the fine grains also happen to be a precious commodity. Humans extract 50 billion tonnes of sand and gravel every year, making it the second most exploited resource on the planet. Can the world keep digging for more? The Down to Earth team investigates.
An insatiable appetite for sand
Laurent Biagetti, the manager of a sand quarry in France's northwestern Normandy region, likens his job to that of an orchestra conductor. Machines dig into the ground, trucks come and go, vessels get loaded with sand on a near-daily basis.
Concrete maker CEMEX scooped out nearly a million tonnes of gravel in 2021 from the mine, from pebbles to fine grains of sand. The different materials will be a key component in the production of concrete and the construction of roads.
"When we exploit a sand mine, we can't just do whatever we want," warns Biagetti. "We need to determine the volumes and areas we'll extract from under a specific timeline," adding that once the reserves run out, the land needs to be restored to its natural state before it's returned to the local constituencies.
The site also collects and recycles rubble, mostly construction waste from the Paris region.
"Sand stocks are becoming increasingly scarce. It's getting very difficult to open quarries or even to extend existing quarries, despite the fact that sand is essential to our everyday lives," he says.
Is the world running out of sand?
Sand has become the second most exploited resource on Earth after water, with experts warning we could soon reach a crisis point. Even though global stocks might seem infinite, we are in fact depleting sand reserves faster than they can be replenished. Around the world, calls to put a break on the expansion of sand mines are growing louder.
On the French Atlantic coast, a small town of a few thousand inhabitants is rising up against a powerful opponent: two massive sand mines that have been nibbling away at their land.
The mines, run by industry giants Lafarge and GSM, already cover a surface of 115 hectares. The two companies have applied for an extension permit that could see their quarries grow by several dozen hectares.
A citizens' association, La tête dans le sable (Head stuck in the sand), is firmly standing in their way. Its members say they won't let their rural community get sacrificed for the sake of sand.
"The mining companies will dig huge holes. And that means the aquifer, water reserves found underground which are normally out of sight, are going to be burst open," explains Sylvain Jallot, the association's spokesperson.
The non-profit claims that least 1 million cubic metres of water will evaporate from the surface each year, the equivalent of the domestic water consumption of about 30,000 people.
The group has already organised several rallies and is leading a legal battle against the mining companies.
"Our goal in stopping these quarry extensions is to say let's be careful with this resource," says Jallot. "It's not by blindly authorising them and sticking our heads in the sand that we're going to solve our sand problems."
Once the mines close, can ecosystems heal?
In her laboratory in the western French region of Brittany, Laure Simplet closely examines samples of sand and sludge arranged in thin layers. A team of scientists from France's IFREMER (National Institute for Ocean Science) led by Simplet collected the samples from a former mining ground off the coast of La Rochelle. A total of 40 million cubic metres were extracted from the site with the help of dredging barges, giant vacuum cleaners designed to suck up sand.
As a matter of fact, sand is not only mined from quarries but also from the bottom of the sea. Understanding the long-term impact of marine sand extraction has been at the heart of Simplet's research.
"The point of our research, now that the mining has stopped, is to try and observe and understand how the seabed will be able to recover," she explains.
Her scientific work has already produced some results. The ecosystem found on the ocean floor has been modified, she says, the layers of sludge becoming thicker than they used to be. But contrary to previous assumptions, the area has not turned into a dead zone.
New forms of life have emerged, with some species now calling the former mining ground home. But it could take many more years, at least another decade, for the scientists to get a full picture of how ecosystems have evolved: "The whole point of looking at what happened there is to learn from past mistakes and come up with recommendations for the future. But also to see how far we can modify the natural environment of the seabed without disrupting its biological equilibrium," says Simplet.
Replacing sand
Whether ecosystems can recover to a certain extent, the overarching problem remains the same: our appetite for sand is only expected to grow. By the middle of the century, 70 percent of the world's population will live in urban areas. We'll need more buildings but also viable solutions to get them off the ground without relying on sand.
The construction industry, which heavily relies on sand, is on the hunt for alternatives.
Cycle Terre, a startup based in Paris, is banking on a seemingly updated material: mudbrick. The company collects excavated soil from construction works in Paris, turning it into compressed bricks made of soil, water and a small fraction of sand.
For Cycle Terre's Managing Director Teddy Dusausaye, it's a no-brainer: "We use a lot less sand than concrete."
While concrete is usually made of two-thirds sand, mudbrick needs less than a third of that. For now, the company is still obliged to add sand to its formula, as the type of soil found in the Paris region naturally contains little sand. They're confident, however, that expanding their activities to other regions will allow them to unearth other soil types. "Mudbrick has ample potential and must be part of the future of housing," Dusausaye concludes.
