Degerhamn, Sweden

As far as the eye can see, the only thing polluting our pristine environment is the gas-guzzling car I’m riding in.

It’s a chilly April morning in Kalmar county in southern Sweden, and as we drive past pastel-colored wooden houses separated by acres of farmland, Martin Olofsson, a researcher at Linnaeus University, tells me that only 5% of the electricity Swedes consume comes from burning fossil fuels. That’s nothing compared to, say, the US, where two thirds of electricity are fossil-fuel derived.

But for Sweden, even that’s not good enough. In February, the country’s green party introduced a bill that would commit the country to reaching net-zero emissions of greenhouse gases by 2045. On June 15, the bill became the Climate Act and the Scandinavian country is now legally bound to deliver on that goal.

We’re driving to one of last places in Sweden to catch up with the country’s green ambitions to reduce emissions. I know we’ve arrived when two massive red chimneys appear on the horizon, spitting globs of white smoke into the sky. They’re part of a 130-year-old cement factory in the otherwise angelic village of Degerhamn, on a sliver of land between the Baltic Sea to the east, and the Kalmar Strait to the west, beyond which lies mainland Sweden.

Olofsson has brought me here—about a five-hour drive south of the capital Stockholm—to see how cutting-edge science is turning this cement factory from climate destroyer to savior, transforming those chimneys into nothing more than innocuous architectural oddities, and giving Sweden a real shot at becoming the first industrialized country to become 100% green.

Making the world is also destroying it

Cement seems boring, but perhaps that’s only because its usefulness has made it ubiquitous. It is the world’s most-used building material, and in 2016 alone, we consumed 4.2 billion metric tons of it—roughly 115,000 Empire State Buildings by weight.

The problem is that each ton of cement we use produces more than half a ton of carbon dioxide. In other words, the cement industry contributes 5-6% of all global emissions each year.

Quartz/Akshat Rathi Martin Olofsson of Algoland and Urban Kristoffersen of Cementa (owned by Heidelberg Cement) in a limestone quarry.

That’s because of the chemistry of cement. A key ingredient is quick lime (CaO), produced by heating limestone (CaCO 3 ) until it releases carbon dioxide (CO 2 ). The process requires intense heat, about 1,400°C, generated by burning whatever the cement factory can get its hands on, from household waste to chicken feathers along with lots of coal—which itself produces even more carbon dioxide when burned.

The industry needs to change. Now that nearly all the countries hosting cement factories have made commitments towards the Paris climate agreement, these facilities have no choice but to move towards sustainability in order to meet local regulations. Though other cement makers have also set goals towards becoming greener, the ones set by Heidelberg Cement, which owns the Degerhamn factory, are the most ambitious.

Heidelberg Cement, the world’s fourth-largest cement maker, founded in Germany and operating 160 plants in 60 countries, has committed to producing cement with net-zero emissions by 2030 in its Northern European factories and embraced the ambition for remaining factories worldwide. None of the world’s other top-10 cement makers have set a zero-emissions goal. (Heidelberg has already reduced emissions from its cement by 24% compared to 1990 levels.)

In Sweden, the drive to achieve the zero-emissions goal will most likely come in the form of taxation. Sweden already has one of the world’s highest carbon taxes at about $150 per ton of carbon dioxide, but only power companies pay the full whack. Heavy industries like steel and cement pay less than $10 per ton, because, as part of the EU’s emissions trading scheme, they can circumvent certain national taxes. In a few years, those discounts could disappear because the EU is beginning to recognize that the scheme’s price on emissions is too low and its members, including Sweden, are thinking of ways they can increase the price if the EU doesn’t. At that point, it will be much cheaper for Heidelberg to implement technology to “capture” the carbon dioxide released in the chemical process than to pay a hefty tax on it.

It’s a trend that extends beyond Sweden. Countries around the world are increasingly looking to put a price on emissions so they can deliver on their Paris-agreement promises. For a global conglomerate like Heidelberg, it makes sense to invest today in technology it will need to stay profitable tomorrow.

The most special cement on Earth

Degerhamn is one of hundreds of villages and towns situated on Sweden’s long Baltic Sea coastline. Most of Degerhamn’s 300 or so residents are either directly employed or indirectly supported by the cement plant on its northern border.

In the 1990s, the Degerhamn factory was on the verge of being shut down. Its aging equipment was increasing maintenance costs, and newer Swedish cement factories also owned by Heidelberg were more efficient and cheaper for the company to operate. But then Heidelberg scientists found a niche use for Degerhamn’s cement: underwater construction.

The relatively small amounts of sodium and potassium found in Degerhamn’s limestone mean the cement produced there can be sold as “low-alkali”—known to last longer in ocean water because it can withstand the corrosive effects of salty H 2 O. The premium low-alkali product, used for building bridges or tunnels that traverse bodies of seawater, could be sold at higher prices. Just like that, the factory came back from the brink.

Before I can get a close look at the Degerhamn factory, Urban Kristoffersen, the plant’s quality manager, suggests we drive to the nearby limestone quarry. Groves of tall trees and farms flank the dirt road, which leads to a vast, barren landscape. Over the past 130 years, the cement factory has consumed huge amounts of limestone, leaving behind a flat piece of land, about 1 km (0.6 miles) in each direction, without a single tree in the expanse.

As we approach the quarry, I spot a large excavator filling a haul truck—a vehicle engineered for heavy-duty mining and construction—with rubble. Every few months, Urban says, a team comes with explosives and blasts a large portion of the 10-meter-high limestone wall standing tall in front of us. The trucks then go back and forth between the quarry and the cement plant all day, almost non-stop, feeding the plant with limestone.

Quartz/Akshat Rathi The quarry.

“The mine holds enough limestone to last another 100 years at current production levels,” Kristoffersen says. So as long as there is demand for the product, the cement factory could also run for 100 more years.

When I finally get a tour of the factory, I’m surprised by how few people work there. The plant produces 300 million kg of cement every year, but is run by a staff of just 75. They work in teams of 25-50, in two or three shifts round the clock.

“You can control 95% of the plant sitting in the control room,” Kristoffersen says. A massive screen, split into nine segments, shows a flurry of activity across the plant. In one square, I see crushed bits of material on dusty conveyor belts. In another, a haul truck delivers fresh limestone from the quarry.

What you can’t see is the rotary kiln, the single-largest piece of equipment in the whole plant. The 100-meter-long, 3-meter-diameter cylindrical iron structure is laid at the center of the plant; crushed ingredients enter the kiln at one end, and near-ready cement comes out the other. The chemical trick performed in the kiln is achieved by slowly heating the mixture as it moves through the cylinder—starting at 60°C at one end and reaching 1,400°C at the other. Walking the length of the kiln, which floats only meters above my head, feels like going from the Arctic to the Sahara.

Quartz/Akshat Rathi Martin Olofsson, researcher at Linnaeus University, studies algae samples in his lab in Kalmar.

This is where the fuel is burned and limestone is converted to quick lime, producing large quantities of carbon dioxide and steam along the way. Those gases move up the kiln, through a series of filters to remove other pollutants like sulfur dioxide and soot, then into a cooling unit before being let out through the chimneys.

All of these processes are fairly typical for a cement factory. Olofsson has come to show me what separates the Degerhamn factory from the competition: they’ve figured out how to actually use the waste gases coming out of the chimney.

The green goo

In a corner of the factory, there are neatly lined, large, clear bags of green liquid with gas bubbling through them.

This is part of the Algoland project, the brainchild of environmental scientist Catherine Legrand, executed by her team of researchers from Linnaeus University, and managed by Olofsson. The project has found a way to wield naturally occurring algae to capture carbon dioxide coming from the cement plant before it enters the atmosphere.

It’s elegant: Take water from the Baltic Sea’s Kalmar Strait next to the plant, pump it about 100 meters (330 feet, about the length of a soccer field) into bags that can hold about 3,000 liters (800 gallons) of liquid. Add key nutrients to multiply the naturally occurring algae, and then let them soak in the gases piped to it from the cement plant (what would otherwise be the factory’s waste product) while the sun shines.

Martin Olofsson Ambition to action.

Algae use the same process as trees to convert carbon dioxide and water in the presence of sunlight into sugars and other nutrients needed to grow. The Algoland system in Degerhamn supercharges the photosynthesis the little green critters have mastered over billions of year. In a single pass through the algae mixture, as much as 40% of carbon dioxide is absorbed. Run it through the system a few times, Olofsson says, and it will remove almost all of the greenhouse gas.

What’s more is the algae are rich in proteins and fats. After drying, they can be used as an additive for chicken- and fish-food. Heidelberg is in talks to sell the algae additives to major agricultural companies like Cargill. At its current size, the Algoland system in Degerhamn can only produce about a few kilograms of algae a day. But the plant has all it needs to scale up to make many metric tons of algae daily—light, water, fresh algae, and lots of space—and thus capture many metric tons of carbon dioxide in the process.

The science underlying Algoland is not novel, but what is new is how well it integrates the many parts entailed into an economically feasible carbon-capture plant. The used-up limestone quarry can provide the space; a greenhouse built on it ensures the right temperature and light is available even when the sun’s not shining; and the Baltic Sea is a source for both water and fresh algae.

Quartz/Akshat Rathi Catherine Legrand, professor and deputy vice chancellor at Linnaeus University, stands on the balcony of her lab in Kalmar.

What excites Jan Theulen, Heidelberg’s director of alternate resources, is that many of the cement plants the conglomerate operates have access to similar resources. “We are preparing to scale up the algae project to a commercial scale in Morocco,” Theulen says. (A decision hasn’t been made yet on how big they’ll try to make the Degerhamn project.)

New sites will of course create new challenges. For example, Legrand has no idea whether algae from the Atlantic Ocean will behave just like those found in the Baltic Sea. Local economics will be another challenge. Morocco is considering implementing a price on carbon, but in places where there isn’t a carbon tax, the only economic driver is the market price of algae. Selling it as a food additive will only fetch few dollars per kilogram and that’s unlikely to be enough to recoup capital and operating costs.

How to heat a cold country in the 21st century

In other words, something else is needed in order to make this project economically feasible if it is to be widely used.

Olofsson may have the answer. He’s eager to show me another pilot project in a different corner of Kalmar county. After an hour’s drive, we pull into the parking lot, which looks no different than the lot of any swanky office block in Europe or North America—except for the smoke-billowing chimney behind the building, a clear sign that this is yet another fuel-burning facility.

It’s the site of one of Kalmar Energi’s two carbon-neutral power plants that burn only wood to produce electricity and heat. The company runs the $130-million plant—half owned by Kalmar county and half by the German energy giant Eon—to generate 30 MW of electricity and 85 MW worth of heating for hot water that’s piped into homes throughout the district.

Quartz/Akshat Rathi Kalmar Energi’s fuel: wood harvested from forests within 70km of the power plant.

The power plant is in the middle of a pine forest, and its wood comes from within a 70 km (about 43.5 mile) radius. “That has two advantages,” says Robert Stensson, a Kalmar Energi engineer. “It keeps both the price and the environmental burden of transport as low as possible.”

Apart from coal use at cement and steel plants and driving gasoline-powered cars, heating through natural gas is the main reason Sweden continues to use fossil fuels at all. The country wants to put an end to that. Only 25% of Sweden’s primary energy consumption comes from fossil fuels (compared to more than 80% for the US, for example), and the country wants to reach net-zero emissions by 2045. Burning wood for heat is one potential solution.

Of course, not all of Sweden has access to local wood to burn. There are places—say in a house on one of Sweden’s 20,000 islands—where burning fossil fuels is likely to remain necessary. Additionally, though there’s a push in Sweden to phase out gas-powered vehicles in favor of electric ones, there are likely to be quite a few still burning gas by the 2045 deadline.

Building more algae plants on the Algoland/Degerhamn model could help Sweden attain this goal. Kalmar Energi is already a biomass power plant, and is considered carbon neutral, because, in theory, there’s less carbon dioxide released in the process than would be captured by the trees being burnt. (Though some experts have questioned the concept of biomass carbon neutrality.) And so if a version of the Algoland plant were built here to capture the plant’s carbon dioxide emissions, the plant would technically produce net negative emissions. Or, put another way, it would be mathematically pulling carbon dioxide from the air.

The Algoland team is trying to do just that, with a pilot project here at Kalmar Energi.

Quartz/Akshat Rathi Algae from the Baltic Sea are trapped in Algoland’s carbon-capture contraption.

Like the carbon-capture unit in Algoland’s Degerhamn pilot plant, the Kalmar Energi pilot also makes use of resources available at source. The algae come from a nearby river; the nutrients to feed the algae are sourced from the waste of a nearby cheese factory (which is rich in phosphorus); and the large amounts of water needed to host the algae come from a landfill which would have otherwise needed to be treated separately to deal with the harmful chemicals leaching out of it.

The size of the plant is modest. But early tests show that algae are happily growing in the soup of human-created waste. Kalmar county, through its science initiatives, has shown interest in financially supporting Algoland to incorporate as a company, which will bring it a step closer to being able to scale up its tech to commercial levels.

The zero-emissions gambit

It’s no accident that Sweden is already working on practical solutions to make the final stretch towards zero emissions while the rest of the world struggles to make a dent. The country has been working towards decarbonizing its energy supply for decades. Lacking its own petroleum resources, the oil crises of the 1970s made Sweden realize just how dependent it is on imports. That’s when it started building a fleet of nuclear reactors, which cut the share of the county’s energy from petroleum from 70% to 35% in a matter of 20 years.

Another force that reduced reliance on fossil fuels: a carbon tax. The consumption of oil products has been taxed since the 1920s. In 1991, however, when Sweden wanted to reduce the tax burden on labor and income, it did so by adding taxes on emissions. That tax started at about €30 ($34) per metric ton of greenhouse gas emissions; in 2016 it surpassed €120 ($135)—the highest in the world.

A tax on emissions promotes the use of greener alternatives. Sweden ranks third among all OECD members, a club of rich nations, in the number of green patents produced per million people.

Though most other countries can’t boast of the lead Sweden has, the incredible growth of renewable energy use in the form of hydro, wind, and solar shows that the world is serious about reducing carbon-dioxide emissions. And, yet, according to a study published on Jun. 19 in the Proceedings of the National Academy of Sciences, renewable energy on its own cannot satisfy our ever-growing hunger for energy in the next few decades and thus won’t be enough for us to reduce emissions fast enough to avoid catastrophic climate change.

The world relies too heavily on fossil fuels to produce electricity, and in industries like cement and steel there is no alternative to not producing large amounts of carbon dioxide. That is why, for the climate math to work and bring us to net-zero emissions, each country will have to deploy some form of carbon-capture technology, be it algae developed by Algoland or something else.

Read next: The world’s first “negative emissions” plant has begun operation—turning carbon dioxide into stone

The reporting was supported by a fellowship from the McGraw Center for Business Journalism at the City University of New York Graduate School of Journalism.