The urgent need to decarbonise is a far more acute challenge for cement than most industries. Efficiencies, low-carbon substitutes, and cleaner input fuels will only achieve so much. Cement is a ‘hard-to-abate’ industry because most of its direct emissions are process emissions – carbon dioxide released unavoidably from the raw material when heated. For these process emissions, carbon capture is essentially the only viable decarbonisation option.
Even accounting for other potential carbon emissions reductions, the Global Cement and Concrete Association expect that 1.4 billion tonnes of CO₂ will need to be captured and stored annually by 2050 for the industry to fulfil its commitments and reach net zero.
Decarbonisation solutions must balance environmental goals with social and economic considerations in a just transition to net zero. It is this challenge that Leilac exists to help solve.
The Leilac technology
Leilac’s technology was developed for, and in partnership with, the cement and lime industries. As shown in figure 1, it uses calciner tubes to deliver radiative heat to limestone or cement meal. This unique approach simply separates the reaction products from exhaust gases and air, enabling process emissions to be efficiently captured as high purity CO₂. This innovation marks a step change from other carbon capture solutions that require energy intensive processes and additional chemicals or solvents to separate gases from gases.
A techno-economic analysis: low-cost and future-proof pathways to net zero
The study includes a techno-economic analysis of multiple integration options, the use of alternative fuels, biomass, electrification, and Leilac’s technology used in combination with a post-combustion capture unit for emissions from carbon-based fuels.
Decarbonising Cement: Leilac at Full Commercial Scale, a new study produced by the Leilac-2 consortium for the European Union (EU), provides a detailed analysis of the Leilac technology’s potential to deliver flexible and low-cost decarbonisation solutions for a cement plant with a capacity of 1.2 million tonnes of clinker per year, with costs based on central European prices.
Low-cost capture of unavoidable emissions
Through a simple replication of the module being developed for the Leilac-2 demonstration plant, the study finds that a typical full-scale Leilac plant could capture around 600 000 tonnes of CO₂ a year for a cost of ~€33/tonne of CO₂ avoided, or ~€16/tonne of clinker. With transport and storage costs in the range of €15/tonne of CO₂, full CCS avoidance costs may be possible for around €48/tonne of CO₂ avoided.
Currently, the cost of emitting CO₂ within the EU is around €90 under the EU ETS, while in the US, the Inflation Reduction Act increased the incentive to capture CO₂ from industry to US$85 per tonne.
Full-scale implementation of the Leilac technology at a typical cement plant in central Europe could capture CO₂ emissions worth €53 million per year for an annual cost of €20 million, excluding CO₂ transport and storage.
Unlocking low-cost net-zero cement
In this case, the addition of a post-combustion capture (PCC) unit can increase CO₂ avoidance rates and deliver carbon neutral or even carbon negative cement. The combined use of the Leilac technology – to capture the unavoidable process emissions – and any viable ‘flue gas capture’ process can also enable significant synergies.
With Leilac capturing the process emissions, the required PCC unit is only one-quarter of the size that would otherwise be required if it were the only technology used for carbon capture. Importantly, this dual capture technology scenario means that the energy requirements of the small PCC unit could be sourced predominantly from waste heat, all but eliminating its largest operating cost.
Using a formulated amine as an illustrative example PCC technology, the techno-economic analysis found that a combined Leilac + PCC system could reach net zero for ~€39/t CO₂ avoided (excluding transport and storage). A comparative scenario using the same post-combustion capture technology for all plant emissions resulted in a 90% cost increase compared with a dual Leilac and post-combustion capture approach.
Low impact retrofit
The study finds that the Leilac technology could be successfully retrofitted to a typical cement plant with minimal downtime, and all costs presented include the cost of taking the cement plant offline to complete the installation.
The Leilac technology has a similar footprint to the existing pre-heater tower, and its modular design can enable flexible layout, process and integration options tailored to a given host plant.
Leilac’s technology is being developed to run on a variety of energy sources, including electricity and alternative fuels, biomass and hydrogen.
Fuel switching from negatively priced alternative fuels resulted in significant cost increases, with avoidance costs of €69/t CO₂ for biomass and €138/t CO₂ for electrification. A sensitivity analysis provides further insights on the effect of key cost drivers.
Potential fuel optionality that includes alternative fuels, hydrogen and electrification, fuel switching, and grid-load balancing capabilities has the potential to provide future-proof solutions for the industry. The Leilac technology also allows for a transition to clean fuels or the addition of a post-combustion capture unit for fuel emissions at a later date, providing ongoing fuel optionality and the ability to scale decarbonisation rates over time. The emissions avoidance rates and associated financial costs for the main scenarios studied are summarised in table 1.
Towards full scale
The concept of the Leilac technology has been proven at pilot scale through the EU Horizon2020-funded Leilac-1 pilot plant at Heidelberg Material’s cement plant in Lixhe, Belgium.
Leilac-1 has the capacity to capture 25 000 tonnes of CO₂ per year at more than 95% purity. This equates to about 5% of a typical cement plant’s process CO₂ emissions.
Building on this success, Leilac-2, which is being built at Heidelberg Materials’ cement plant in Hannover, Germany, will build and validate a retrofittable and replicable module with a capture capacity of 100 000 tonnes of CO₂ per year, or about 20% of a typical cement plant’s process CO₂ emissions. Leilac-2 includes a lighter, cheaper and simplified modular unit, with four calciner tubes within one furnace chamber, and aims to operate fully on alternative fuel.
The techno-economic study assessed the capture rate and costs for full-scale Leilac plants based on duplicating the current Leilac-2 design (4-tube modules), representing the simplest approach to applying the design at full-scale. Future module designs, containing more tubes per module, may provide improved design solutions that further reduce capture costs.
This is particularly the case in the context of the regulatory incentives being implemented by governments around the world.
The CO₂ abatement costs presented in the techno-economic report, with flexible, low-impact and retrofittable integration options, provide economical solutions for cement decarbonisation.
Capturing cement’s carbon emissions, however, only solves part of the problem. The captured CO₂ must be transported, used, or in most cases, permanently stored. The vast majority of cement plants currently lack access to CO₂ transport and storage infrastructure, and expected costs are location specific and vary dramatically. With effective and economical capture solutions on the way, it is access to low-cost CO₂ transport and storage infrastructure that is perhaps the cement industry’s critical path to decarbonisation.
In this regard, the EU’s commitment to build 50 million tonnes of annual CO2 storage capacity by 2030 under the Net Zero Industry Act is an example of the critical role government has to play. Such policy leadership provides significant support to industrial decarbonisation efforts by helping to develop the required infrastructure and reduce overall costs through coordinated cross-industry initiatives. It also helps to provide certainty for investment in carbon capture projects.
The results presented in the techno-economic study are illustrative and based on central European prices. Certain costs, particularly electricity, vary dramatically by region, and regional and plant specific analysis is provided through a scoping study. To learn more about how we can help achieve a just transition to sustainable cement, please email firstname.lastname@example.org.