Cement might not be as bad for the planet as we thought
Three new studies show promise for carbon capture.
City sidewalks and brick buildings look a little greener today, thanks to new research showing that cement can soak up CO2. That’s not the only good news to come out this week. A team of German scientists engineered photosynthesis to be faster and more efficient. And a team of Americans buried 1,000 tons of carbon pollution underground.
If humanity is to keep warming below 2º C — considered to be the upper limit of manageable climate change — we need to do more than slash carbon pollution. We must also scrub carbon dioxide from the atmosphere. Around half a century from now, we’ll need to remove as much CO2 from the skies as we emit.
You can think of our atmosphere like a bathtub. We’re constantly pouring in carbon dioxide and other heat-trapping gasses. We need to drain the tub before it overflows. That could mean growing forests or developing farms that scrub carbon from the sky. It could also mean new technologies that turn atmospheric CO2 into something benign or even useful, like fuel for your car.
New research illuminates the road ahead. Here are three studies with promise for the future of carbon capture.
Store CO2 in rocks
Scientists have long explored ways to store carbon dioxide underground. One option is to dissolve CO2 into water and inject into a subterranean layer of volcanic rocks. Carbon dioxide reacts with with the rocks, called basalts, to form a new rock, carbonate. In theory, anyway.
A study published in the journal Environmental Science & Technology Letters suggests this just might work. In 2013, researchers injected 1,000 tons of liquid CO2 into a layer of basalt rock more than 4,000 feet underground. Two years later, they dug it up and showed newly formed carbonate rocks bearing the marks of human intervention. Tests showed these rocks contained carbon atoms derived from fossil fuels.
Technologies that trap carbon dioxide from the atmosphere are useless if there is nowhere to dispose of the heat-trapping gas. This study shows the potential of underground storage. Basalts are abundant on Earth, and they can be used to store CO2 scrubbed from factories and power plants.
Engineer plants to capture more CO2
For now, the most cost-effective tools for trapping CO2 are plants, algae, and other photosynthesizing organisms. Leaves, for example, pluck carbon dioxide molecules from the atmosphere and use them to make glucose in a process called the Calvin cycle.
Scientists in Germany have developed a synthetic alternative to the Calvin cycle that makes photosynthesis faster and more efficient, as explained in a new study published in the journal Science. Researchers put together 17 enzymes from nine different plants and animals to create a synthetic version of the cycle, and it worked like gangbusters in the lab. Someday, it may be introduced to bacteria or even plants.
In the years to come, we may see plants that have been engineered to trap more atmospheric carbon dioxide. This would offer another important tool in the effort to curb carbon pollution.
Capture carbon dioxide in cement
In a related story, a new study published in the Nature Geoscience finds that cement might not be as bad for the environment as previously assumed.
Cement is the adhesive in materials like concrete and mortar. To create cement, producers must convert limestone to lime. This process releases CO2. And to generate the heat needed to make cement, producers burn coal or natural gas – two carbon-rich sources of energy.
But as it turns out, cement-based materials like concrete actually trap carbon dioxide over decades. This process offsets a small, but not insignificant portion of the carbon pollution associated with construction.
The results of the study offer another reminder that our efforts should focus on fossil fuels — coal, oil and gas — and not building materials. We should invest heavily in the emerging slate of technologies that will clean up the mess fossil fuels leave behind.