Climate Change's Toughest Obstacle: Cement Production

The cement industry, responsible for approximately 8% of global emissions, is undergoing a significant transformation as companies worldwide strive to reduce its carbon footprint. In 2022, the industry emitted approximately 1.6 billion tonnes of CO2, a figure that could balloon to 3.8 billion tonnes yearly by 2050 without major changes.

One of the key players in this movement is CarbonCure, a company that has saved over 657,000 tonnes of CO2 across 9.4 million truckloads of concrete worldwide. CarbonCure technologies allow for the permanent sequestration of CO2 in concrete, making it a popular choice for sustainable construction projects. For instance, Atlanta's 725 Ponce office tower used CarbonCure concrete for every pour, placing about 36,600 cubic meters of concrete that collectively saved over 680 tonnes of CO2.

Another promising solution is Limestone Calcined Clay Cement (LC3), a product made from abundantly available worldwide materials. LC3 can cut emissions by 40% compared to regular Portland cement while reducing production costs by up to 25%. Countries like India have written LC3 into their national building codes, and major manufacturers like Holcim are scaling up production with plants achieving 50% + clinker reduction.

Replacing cement with slag, LC3, fly ash, or limestone can reduce concrete's emissions by 9-43 percent, with no sacrifice in concrete quality. Nearly any fraction of cement can be replaced while maintaining design strength. For example, fly ash from coal power plants can replace 20-30% of cement and reduce CO2 by about 27%. Field trials routinely show equal 28-day strength with cement replacement.

Ground granulated blast-furnace slag (GGBS) can replace up to 50% of cement, reducing production costs by 3-21% and emissions by up to 43%. Holcim's ECOPact products guarantee "100 percent performance" with ≥30 percent lower embodied CO2.

The US Inflation Reduction Act's tax credits of up to $85 per tonne of stored CO2 significantly improve the economics of carbon capture projects. Companies in Germany, such as Heidelberg Materials, Holcim, and Dyckerhoff, are actively working on reducing CO2 emissions. Heidelberg Materials offers CO2-reduced evoBuild products, Holcim is developing an energy-efficient CO2 capture technology based on amin washing, and Dyckerhoff focuses on clinker reduction, secondary raw materials use, and hydrogen fuel considerations to lower emissions.

Moreover, Brimstone's "carbon-free cement" meets ASTM strength tests (>6,000 psi at 28 d), demonstrating that sustainable solutions can meet industry standards. Fortera's demonstration plant in Redding, California, began producing 15,000 tonnes of low-carbon cement in 2024, with the product showing 70 percent lower emissions than conventional cement.

The cement industry's shift towards sustainability is a global effort, with China, the world's largest cement producer (approximately 2.1 billion tonnes annually), also participating. The industry's transformation is crucial in the fight against climate change, and these innovative solutions are paving the way for a more sustainable future.

| Key Low-CO2 Cement Blends | Clinker Content (%) | CO2 Reduction (%) | |---------------------------|---------------------|--------------------| | Portland Limestone Cement (PLC) | 55-65 | 10-15 | | Blast Furnace Slag Cement (BFSC) | 35-55 | 30-40 | | Limestone Calcined Clay Cement (LC3) | 40-60 | 40 | | Fly Ash Cement | 30-50 | 25-35 | | CarbonCure Concrete | Varies | 20-30 | | Carbon-free cement (Brimstone, Fortera) | Varies | 70 |