Cemex highlighted its Clyngas project at its Alicante cement plant in Spain this week. The project will produce synthesis gas (syngas) from different types of waste for direct injection into the burner at the plant during the combustion process. It is being run in conjunction with Waste to Energy Advanced Solutions (WTEnergy), a company that Cemex invested in at the end of 2022. It is also receiving Euro4.4m in funding from the European Commission (EC) as part of its innovation fund for small scale projects. The initiative estimates that it will save over 400,000t of equivalent CO₂ during the first 10 years of the project's life by replacing petroleum coke with syngas.

Clyngas is another example of Cemex’s innovation with alternative fuels for cement and lime. It follows on from the group’s work with hydrogen injection into cement kilns. As presented at the 15th Global CemFuels Conference 2022 it has been using hydrogen in low volumes as a combustion enhancer in more than 20 plants worldwide. However, it was also looking into using hydrogen more directly as a fuel and as a feedstock for other alternative fuels. WTEnergy’s gasification process could potentially link up to this as it converts waste streams such as wood chips, agricultural waste, refuse derived fuel (RDF), solid recovered fuel (SRF), dry sewage sludge, meat and bone meal, poultry litter and plastics into syngas. WTEnergy then proposes that its gasification process and/or the syngas can be used for power generation and thermal applications. In the case of the Clyngas project it will be the latter, as the gasification process will be used to boost the burnability characteristics of RDF with a high biomass content. One part of this to note is that the syngas can potentially be used to manufacture hydrogen. This would be a useful capability for a cement company, for example, that was already using alternative fuels and was now considering further decarbonisation by switching to using hydrogen.

A few other cement companies have been looking at synthetic fuels too, but this has generally been as a by-product of carbon capture and utilisation. This week Lafarge France, for example, said it had signed a memorandum of understanding with Axens, EDF and IFP Energies Nouvelles for a synthetic fuel production trial. Its plan is to build a unit that will produce synthetic kerosene using captured CO₂ from a carbon capture installation at Lafarge France's Saint-Pierre-La-Cour cement plant. The kerosene will then be sold to airlines. Other examples of cement companies looking at using captured CO₂ to manufacture synthetic fuels include Finnsementti’s pre-engineering study with Aker Carbon Capture to consider producing methanol as a fuel for transport, Holcim’s and TotalEnergies’ various plans of what to do with the CO₂ captured from the-to-be upgraded Obourg cement plant and Cemex Deutschland’s ambitions for its Rüdersdorf plant.

As can be seen above there are different types of synthetic fuels and cement companies are at the research and pilot stages. Although there isn’t a commonly accepted definition of what a synthetic fuel is, the general meaning is that of a fuel made from feedstock using a chemical reaction as opposed to, say, a refining process. The wide variety of potential synthetic fuels puts the confusion over the different types of hydrogen into perspective. However, this may be a problem for a later date if usage by cement companies becomes more serious.

What is a problem, though, has been the EC’s planned legislation to phase out the use of industrial CO₂ in synthetic fuels by 2041. Cembureau, the European cement industry association, warned in late 2022 of the issues this would pose for industries trying to find a way to utilise their CO₂ emissions where storage was too difficult or expensive. Its view was that while synthetic fuels using industrial CO₂ are not fully net-zero, as the captured CO₂ is later released into the atmosphere, it is a necessary short to medium term step for sectors trying to make the transition. Companies trying to build industrial-scale chemical plants for synthetic fuels need running periods of 20 to 30 years to achieve payback. As of March 2023 Cembureau was still concerned about the implication of proposed regulations, specifically with regards to the proposed criteria for which synthetic fuels could be used, based on their greenhouse gas emissions savings (at least 70% compared to the regular fuels being replaced). It directly linked this to synthetic fuels projects being launched by the cement sector that might be adversely affected by the new rules. The EC published the legislation in late June 2023 and it is set to become legal in mid-July 2023.

Using synthetic fuels either as a fuel or a by-product from cement production is an area of interest currently with the projects detailed above and others in progress. One vision for their use in Europe, at least, is that they might offer a route for carbon capture for cement plants without access to the logistic networks necessary for sequestration. Whether they find a place in cement manufacture either on a transitional basis or over a longer term should become clearer over the coming decade. Yet the EC’s new rules are likely to slow this process down as at least some of the planned pilots may become unviable in Europe. Other jurisdictions around the world take note.