Forget carbon neutral, Northwestern develops carbon NEGATIVE concrete

Depending on who you believe, concrete is responsible for between 5 and 10% of global carbon emissions. That’s a lot of carbon, and the quest for carbon neutral concrete has become a multibillion-dollar endeavor – but a team of scientists from Northwestern University thinks they’ve cracked it, and gone one better: carbon negative concrete.

Using a combination of seawater, electricity, and carbon dioxide (CO₂), scientists at Chicago‘s Northwestern University Engineering have developed a new building material that goes beyond reducing emissions. The new material acts like concrete, but actively captures CO₂ that’s already in the air and locks it away. Permanently.

Impressive as that is in itself, the Northwestern process goes beyond “just” concrete. The scientists involved claim similar processes could also be applied to cement, paints, and plasters.

We have developed a new approach that allows us to use seawater to create carbon-negative construction materials. Cement, concrete, paint, and plasters are customarily composed of or derived from calcium- and magnesium-based minerals, which are often sourced from aggregates –– what we call sand. Currently, sand is sourced through mining from mountains, riverbeds, coasts and the ocean floor. In collaboration with Cemex, we have devised an alternative approach to source sand — not by digging into the Earth but by harnessing electricity and CO₂ to grow sand-like materials in seawater.

Dr. Alessandro Rotta Loria, PhD | NORTHWESTERN

To generate the carbon-negative building materials, Dr. Rotta Loria’s team of inserted electrodes into seawater and applying a low electric current, splitting water molecules into hydrogen gas and hydroxide ions. With the current still on, they bubbled CO₂ gas through seawater, changing the chemical composition of the water and increasing the concentration of bicarbonate ions. All those ions then reacted naturally with minerals in the seawater creating solid materials like calcium carbonate and magnesium hydroxide.

The calcium carbonate acts as a carbon sink, while magnesium hydroxide sequesters harmful carbon emissions through further interactions with CO₂.

That … kinda looks like concrete

The carbon negative materials are made in a way that’s conceptually similar to the way mollusks and corals make shells and reefs, respectively. “But instead of metabolic energy,” writes Amanda Morris, “(the team) applied electrical energy to initiate the process and boosted mineralization with the injection of CO₂.”

“The appeal of such an approach is the attention that is being given to the ecosystem and using science to harness the elements in the contemporary environment to develop valuable products for several industries and preserve resources,” said Davide Zampini, vice president of global R&D at Cemex, a large-scale manufacturer of ready-mix concrete that was recently recognized as one of the world’s most ethical companies (which, I mean– whatever).

This latest Northwestern material study builds on previous work from Dr. Rotta Loria’s lab to store CO₂ long term in concrete.

Electrek’s Take

I’ve long held a tin-hat theory that life on Earth has always been artificial life, it’s just so small and evolved so far ahead of what we ourselves can make that we don’t recognize it. Stuff like this just reinforces that insanity – but all that’s beside the point. This is really impressive tech, and we’re well past the point where simply limiting carbon emissions will lead to a meaningful reduction in anthropogenic climate change.

We need to put the bad stuff back in the ground. These guys are doing that.

SOURCE | IMAGES: Northwestern; featured image by Ablazejo, under a CC License.

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