While few things are set in stone, cement has long reigned as one of the most commonly used materials in the world. However, its reign comes with a notoriously dirty reputation regarding the environment.
Cement is a necessary ingredient in concrete, and — because it is cheap and durable — 4.4 billion tons of cement is produced annually. According to a 2023 report from management consulting company McKinsey and reported by CNBC, that weight is the equivalent of 50,000 fully loaded airplanes.
Freethink reports that the cement industry accounts for 8% of global carbon pollution, roughly three times as much as the notoriously polluting aviation industry.
The real dirt, however, comes in reporting that shares good news: Researchers at MIT have developed a low-carbon cement that has officially exceeded industry standards for strength, durability, and more.
The most common kind of cement is Portland cement. Freethink explains that to make this cement, manufacturers bake limestone in kilns heated to around 2,400 degrees Fahrenheit, separating the limestone into carbon dioxide (CO2) and lime — the ingredients needed for cement.
The CO2 is then mixed with the exhaust from the dirty energy sources burned to heat the kilns, and since it is neither cheap nor easy to capture, the planet-warming gas is released into the atmosphere.
Scientists have been working tirelessly on a solution to the polluting process. Now, Sublime Systems, the startup founded by the MIT researchers, has reportedly developed a process that nearly eliminates the carbon pollution from cement production.
Their Sublime Cement replaces heat with a series of electrochemical reactions powered by clean energy at ambient temperatures to pull the lime from the rock, as reported by Freethink. Because the remaining CO2 is not diluted by other exhaust gases, it’s easier to capture and store.
“I think for the layperson, it’s easiest for them to understand how we take that high-temperature, fossil-driven process and replace it with something that is powered by electrons. And we’re using electrons to push these chemical reactions,” Sublime Systems co-founder Leah Ellis told CNBC.
The Sublime Cement has met required industry performance standards and earned a C1157 designation from ASTM International. Many building codes forbid using cement that doesn’t meet ASTM standards, so this designation removes a major hurdle to integrating Sublime Cement into the construction industry.
“When we are at full scale, we do expect that we will compete on cost with Portland cement,” Ellis told Carbon Herald.
February 11, 2025
February 4, 2025