Cement production is a significant contributor to global carbon emissions, accounting for at least 8% annually, making it one of the most challenging "hard-to-abate" industries to decarbonize. Despite this, some industry leaders, like Cemex CFO Maher Al-Haffar, believe the transition can be value-creating rather than value-destructive for shareholders. The majority of emissions (90%) come from clinker production, primarily due to the high energy needed to heat limestone and the chemical reaction (limestone calcination) that releases 60% of clinker's emissions. Current incentives, such as the EU's emissions trading system, offer some motivation for change, with carbon prices around €80 per tonne, though free allowances for heavy industries like cement have dampened their immediate impact.
The most effective and cost-saving decarbonization method currently involves substituting a portion of clinker with supplementary cementitious materials (SCMs) like fly ash or slag, which can cut up to 40% of cement emissions. Beyond this, carbon capture, utilization, and storage (CCUS) technologies offer another avenue to reduce the carbon footprint of existing plants, though they are currently expensive and add to production costs. Companies like Heidelberg Materials are deploying commercial-scale CCUS, with a plant in Norway capturing 50% of emissions and another in Wales aiming for 95% capture by 2029. ING analysis suggests CCUS can reduce cement emissions by about 85% and increase production costs by only about 10% if CO2 can be transported and stored within a 150 km radius, with costs ranging from €50 to €200 per tonne of carbon.
Some startups are fundamentally rethinking cement manufacturing. California-based Brimstone replaces limestone with non-carbonate silicate, eliminating the 60% of emissions from limestone calcination, and is building a pilot plant. However, it still relies on high-heat kilns for the remaining 40% of emissions. Massachusetts-based Sublime Systems uses electricity instead of heat to extract calcium from rocks, addressing both limestone emissions and kiln heat, though its product is not traditional Portland cement. Sublime's pilot plant has been operational since 2023, with a commercial plant under construction. Scaling these new technologies will require significant time, investment, and potentially regulatory support, as displacing over 3,000 traditional cement kilns globally is a massive undertaking. The industry faces an innovator's dilemma: integrating new, sustainable production methods while older, profitable methods persist.
