The Carbon Solution

As the cold, hard reality of the expense of carbon sequestration weighs heavily on the industry’s shoulders, it is important to question whether it truly is the ultimate solution. Geologic sequestration projects, or their even more expensive cousin ‘sustainable’ e-fuels, are high stakes ventures with significant electricity and water needs – and eye watering costs – with no benefits beyond decarbonisation (as important as that is).

Has this question been approached from the wrong angle? Cement is an engineering-intensive industry, and 'big problems call for big technical solutions' is the rallying cry. Or, as often heard, the only proven, full scale solutions are carbon capture & storage (CCS) or sustainable e-fuels (fuels made by combining H₂ with captured CO₂).

But what if the perspective shifts to that of the concrete user – those needing concrete for buildings, infrastructure, or other applications? Perhaps key performance indicators (KPI) should focus on kg/m3 of delivered concrete, which ties nicely into customer KPIs of kg/m2 of floorspace or kg/km of highway. ‘What gets measured gets done’ is a proven management mantra, and so the selection of the KPIs will steer the entire strategy.

Can net zero concrete in buildings and infrastructure be achieved without relying on CCS or e-fuels by rethinking final products from the buyer's perspective?

Can a ‘silver buckshot’ approach – targeting multiple solutions – be more effective than searching for a single 'silver bullet' to decarbonise the industry?

The silver buckshot approach

There are a number of decarbonisation strategies that make sense even without monetising the carbon benefit attained. These include energy efficiency measures, replacing fossil fuels with lower carbon fuels (often financed by waste tipping fees), new low clinker content formulations, and new cementitious products. Even electrification is becoming a low cost choice in multiple applications. These investments can be considered 'no regrets' investments, even in uncertain times where decarbonisation policies are in political flux. Carbon pricing systems or tax credits can make them even more profitable.

Adding smart design practices in collaboration with the builder can further decarbonise the final building. In a recent collaboration between The Daniels Corporation and Lafarge Canada (East), a 25% reduction in carbon in the delivered concrete was achieved simply by identifying where schedule slack in non-critical path project components could be tolerated and applying a smart mix design strategy. Thirty five different mix designs were used to accomplish this reduction, with no impact on the building’s schedule.

Some net zero roadmaps, like the 'Concrete Zero Roadmap' prepared by the Cement Association of Canada (CAC), show that a combination of all of the above ‘no regrets’ measures could reduce the carbon content of new buildings and infrastructure by two thirds, much of this at low or no cost. Certainly nowhere near the cost of CCUS, which is well over US$100/t of CO₂.

How about measures that come with a cost? If the last measure in a net zero strategy is CCS at over US$100/t of CO₂, then this opens the door to solutions that are still expensive, but less so in comparison. Many other solutions with lower costs than CCUS have yet to be fully explored. Plants that have installed CCS or e-fuel systems may find themselves competing against plants that have pursued a different, multi-path approach to achieving net-zero status, at much lower costs.

Some examples of these multi-path solutions are provided in this article, and innovators who forsee the future need for decarbonisation are actively working on these solutions. It is worth noting that many of these alternative solutions produce sellable products in addition to their decarbonisation benefits, and their environmental benefits contibute to the industry’s overall decarbonisation efforts (not always the case in CCS and e-fuels strategies).

Non-calcining raw materials

There are a number of sources of calcium that are already in the oxide form and so do not produce CO₂ during cement production. Natural minerals such as wollastonite, serpentine, and olivine may be able to play a partial role in the formulation of clinker. Of course, the mineral resources may not be co-located near the cement plant and a processing step may be needed, but in comparison to CCS & e-fuel costs these added costs could be much lower. In other cases, waste materials from other industries and mining operations may provide many of the necessary minerals needed for traditional clinker production, often at a much lower cost than virgin minerals. Concrete rubble is already being used as a raw material in cement production. Solidia Technologies continues to explore alternative cement formulations, similar to wollastonite, which produce cement and resulting concrete that cure with CO₂.

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Read the article online at: https://www.worldcement.com/special-reports/12032025/the-carbon-solution/