Sweden leads the push to take GHGs out of the cement industry

Sweden is utilizing a new technology that might help green the cement industry, a problem that has proved quite intractable up until now.

Cement and concrete is the world's most-used building material, but it's production is a very carbon-intensive process: each ton of cement creates half a ton of carbon dioxide and other greenhouse gases (GHGs), and worldwide cement production on its own is estimated to contribute a huge 5-6% of global CO2 emissions. Part of the cement production process involves heating limestone to 1400°C in order to turn it into quick lime. This is very energy-intensive in itself, but the main problem is that this chemical process produces CO2 as a by-product, and lots of it.

Now, Sweden is one of the world's greenest countries. Only 25% of the country's primary energy consumption comes from fossil fuels, and its goal is to become a net-zero producer of CO2 by 2045. It first introduced a carbon tax over 40 years ago, after the shock of the oil crises of the 1970s, and currently has one of the world's highest carbon taxes, at $150 per ton. However, only power companies pay the full whack of these carbon taxes - most industrial companies can take advantage of EU loopholes allowing them to circumvent national taxes by trading emissions on the open market, which means that they may actually pay as little as $10 per ton. That EU price will increase, though, and more environmentally-conscious companies like the huge German-owned cement producer Heidelberg (which has its own ambitious goal of achieving net-zero CO2 production by 2030) are looking for ways to improve their own industry's record.

At their facility in Degerhamn, Sweden, Heidelberg is now using a process in which a green goo of naturally-occurring algae from the nearby Baltic Sea makes use of the CO2 from the cement plant in its own natural photosynthesis process. The science behind it is not particularly new, but the supercharged process used by Heidelberg was developed by environmental scientist Catherine Legrand and her team of researchers at Sweden's Linnaeus University. A single pass through the algae removes up to 45% of the greenhouse gas, and a few more passes remove almost all of the CO2 before the cleaned-up exhaust is released into the air. Even better, the resulting algae is rich in fats and proteins and can be used in feed for chickens and farmed fish.

It is not yet clear whether the new process will translate well to other sites and other types of algae, and the economics are partially dependent on the price farmers and feed companies are willing to pay for the algae animal-feed product. But full marks for Heidelberg and Sweden for leading the charge to address a particularly knotty greenhouse gas problem.