This article originally appeared in the Precast Today Q1 2023 edition.
By Michael Ireland
From a rush among developers to remove carbon from every part of their construction projects to major cities considering net zero building codes, the drive to cut carbon from tomorrow’s structures is gaining momentum.
Commercial real estate companies are seeing a trend among clients who prefer moving into buildings that meet certain sustainability metrics as they seek to lower their Scope 3 greenhouse gas emissions. In the residential sector, states and counties are starting to enact building codes that limit carbon emissions from concrete.
By taking a holistic view of these trends, it is clear that demand for low-carbon materials only will increase in the coming years. Fortunately, the U.S. cement industry is ahead of this shift in consumer demand and regulatory policy.
The industry has been focusing on reducing its carbon emissions since the mid-1990s, has already developed lower-carbon blends like portland-limestone cement (PLC) and is working to further reduce carbon from its products while also dramatically cutting emissions from its manufacturing processes – with an ultimate goal of carbon neutrality even as demand increases.
From decarbonization technologies to innovations in process optimization, the timelines for new products with lower carbon footprints vary, but there are existing low-carbon cements that can act as a powerful short-term lever for CO2 reduction.
Lower-carbon cements are on the market, and the industry is on the cusp of much greater consumption of PLC, a product that reduces CO2 emissions by about 10% and is just as durable as traditional portland cement. Currently, 46 state departments of transportation – major consumers of cement – have approved the use of PLC. Increased market acceptance has spurred cement manufacturers to shift production in multiple plants entirely to PLC as innovation continues.
Beyond PLC, ternary blended cements – mixes that incorporate by-products from other industrial processes such as fly ash or calcined clay – promise similarly high performance with significant CO2 reduction. Ternary cements are still in the early stages, but cement manufacturers outside the United States are pushing for greater market preparedness, such as standardization in Europe.
The widespread usage of these products is the low-hanging fruit in the push to carbon neutrality with PLC and ternary blends offering immediate opportunities to reduce emissions. Longer-term levers to decarbonize cement plants are in development, and some are ready for implementation.
One such lever is the increased use of technology to optimize cement production, particularly through artificial intelligence (AI) and machine learning (ML).
Today, plant optimization is a difficult task, given the high number of process variables and adjustments needed in real time. But studies have identified five areas in which AI and ML can create a smarter – and greener – cement plant. The first of these is predictive maintenance, in which ML processes can analyze historical and real-time data to predict breakdown occurrences and the need for preventative maintenance. Using ML in this way could reduce maintenance costs by 20% and vastly improve efficiencies as a result.
Additionally, both AI and ML digitally can recreate a cement plant to analyze process data and other variables to model them in a variety of scenarios, enabling plant operators to maximize efficiencies in the physical plant.
Predictive analytics can analyze the quality of cement in real time, leading to the optimal use of limestone, milling time and other processes – further maximizing efficiencies and reducing costs in the meantime.
AI and ML also can be used to optimize the combustion of alternative fuels in a cement plant, using non-fossil fuel-based materials for energy – a technology that already is in use in some cement plants that are looking to shift to 100% alternative fuels in the near future. Finally, these technologies can be used to optimize the cement supply chain, improving traceability in the process.
Stopping Emissions Before Release
While some process optimization technologies start to appear on the market, another carbon reduction technology with the potential to stop emissions before they are released has taken its first tentative steps toward commercialization.
There currently are four cement plants in the United States – such as a collaboration between Lehigh Hanson (now called Heidelberg Materials) and Fortera in Redding, Calif., and two other plants that recently received funding from the U.S. Department of Energy (DOE) – that are implementing pilot projects for carbon capture, utilization and storage (CCUS). This technology will extract and sequester CO2 from the chemical reaction that takes place in the kiln as cement is being produced, the chemical fact of life that is responsible for more than 60% of emissions in the cement manufacturing process.
Positive steps have been taken in accelerating the development of CCUS technologies, most notably in Congress, where the 45Q tax credit has been enhanced. The tax credit incentivizes investments in carbon sequestration and reduces the financial risk companies assume when investing in early-stage CCUS projects. As already noted, the federal government through the DOE is making funds available for CCUS projects across a wide range of industries in which carbon emissions are hard to abate. Carbon capture is one of the four key pathways outlined in the department’s Industrial Decarbonization Roadmap.
A crucial central cog in the drive toward a carbon neutral cement industry, with low-carbon products, is collaboration – not just in the cement industry itself but across the entire cement-concrete-construction value chain. A collective ambition toward carbon neutrality is vital if the processes and products outlined above are to reach commercialization. To that end, the Portland Cement Association, which represents the majority of U.S. cement manufacturers, released its Roadmap to Carbon Neutrality last year. The Roadmap outlines pathways for the entire value chain to reduce emissions.
Encouragingly, the industry is seeing greater demand for low-carbon materials that drives innovation at the top of the value chain along with regulatory approval at the state level for products such PLC, which will help reduce CO2 emissions in the short term. In the future, concerted, collaborative efforts must be allied with innovation to maximize the benefits of technologies like CCUS to create an entirely carbon neutral industry producing cutting edge, low-carbon cement.
Michael Ireland is president and CEO of the Portland Cement Association.