Every year cement production contributes about 5% of the global emissions generated by humans. Any improvement around cement production will have a good impact on lowering carbon entering our atmosphere. In Sweden there’s one company using algae to lower its emissions. The country has carbon emission rates that are likely increasing in the next few years, which has inspired the cement company to figure out how to avoid paying more for producing the same amount of cement. Their solution: pumping the carbon output from their cement factory onto algae which then inhales all that delicious carbon, once the algae dies it becomes food.

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.
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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.

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