For decades heavy industry around Dunkirk in northern France has belched out millions of metric tons of climate-heating gases.

Now the area close to the Belgium border—one of Europe’s industrial powerhouses—wants to catch its pollution before it escapes.

With factories turning out steel, cement and fertilizers, the Dunkirk area produces more carbon dioxide (CO2) than any other industrial region in France.

In Rety, about an hour’s drive from the port city, a never-ending stream of lorries brings limestone to a plant run by Belgian giant Lhoist, the world leader in quicklime production.

The limestone is heated to more than 1,000 degrees Celsius (1,830 degrees Fahrenheit) for 24 hours in kilns 50 meters (165 feet) tall to produce the calcium oxide needed by the steel and paper pulp industries.

“We have the capacity to produce 700,000 tons of quicklime a year, so we emit about an equivalent amount of CO2,” said Yves Boraccino, the manager of the plant in Rety, where nearly every surface is coated in white dust from a nearby quarry.

Freezing the CO2

Two-thirds of that CO2 is belched out of the plant’s chimneys during the limestone calcination process.

The remainder comes from the fossil fuels used to fire up the kilns.

In 2025, the site hopes to start equipping itself with a new mini-factory to captur