This week we covered Capitol Aggregates’ order of an alternative fuels (AF) system from ATS Walter USA. The story is notable because it is an AF project for a cement plant in the US. Thermal substitution rates (TSR) of AF in the US have typically been lower than in the European Union (EU), but this could be changing.
The order was confirmed publicly at the end of September 2025. The subsidiary of ATS Group will supply a solid AF metering and conveying system to the integrated plant in San Antonio, Texas. The system will include a moving floor receiving station, chain belt conveyors, a screen and a separator, dosing equipment, an air-supported belt conveyor and an injection system. ATS Walter says that, by the end of 2026, it will have supplied four AF projects in North America. As an aside, Capitol Aggregates also mentioned in the press release that it “...views sustainability as essential to long-term success.” This sentiment is backed up by the fact that the plant built an early commercial carbon capture unit in the 2010s!
Data from the American Cement Association (ACA) revealed that the AF TSR in the US reached 16% in 2023 from 14.6% in 2022. This compares to a 58% rate in the EU in 2022. It is also worth noting that, in the US the share of gas in the cement industry energy mix rose from 25% to 31%. The ACA attributed this change to a falling price of gas. It added that the coal and petroleum share of the fuel mix fell to its lowest level since 1974. The point here is that the energy mix used by cement plants changes over time regardless of sustainability trends.
Research by LEK Consulting estimated that 60 of the 87 cement plants in the US had a TSR of below 20% in 2023. 39 of these were believed to have a TSR of under 5%. It summarised that hazardous waste and tyre-derived fuels have tended to predominate in the US compared to refuse-derived fuel (RDF) in the EU and elsewhere. LEK went on to say that its research suggested that a quarter of cement plants in the US were likely to install an AF feeding system in 2024 or 2025. This is likely to be the highest rate of AF uptake in the US cement sector to date.
The ACA reckons in its sustainability roadmap that with the right policies and regulations the country’s AF TSR could reach as high as 50%. Its policy suggestions include: reduce permitting barriers to use of so-called non-hazardous secondary materials (NHSM) fuels in industrial manufacturing; treating waste-to-industrial energy as valid recycling use; building robust recycling infrastructure and markets that incentivise the use of non-recycled material streams as industrial AF; community education and support for use of low carbon AF; and increasing the use of NHSMs to divert these materials from landfills. This can be mostly summarised as supporting the uptake of RDF through better permitting and building up the infrastructure and markets for it. LEK also identified the same issue. It called for the adoption of landfill reduction targets or zero-landfill policies by commercial and industrial waste generators. However, LEK believes that, even if this were done, current sources of high-quality RDF in the US would not be able to increase the TSR to even 20%.
News from Capitol Aggregates and others about AF projects in the US are encouraging. If LEK’s research is indicative then a step change in the TSR in the country’s cement sector is already underway. The beauty of AF usage is that it can both potentially cut fuel costs and reduce CO2 emissions. It won’t be easy as new supply chains for refuse byproducts are built and utilised. Yet, as the ACA is advocating, it is possible and worthwhile.
The 1st CemFuels Asia Conference will take place in Bangkok in February 2026 and the 19th Global CemFuels Conference will take place in September 2026 in Geneva
