(July 2024 Edition)

“The cost and complexity of carbon capture technologies and the difficulty in customising CCUS solutions to individual plants represents a significant hurdle to adoption.”   

  • Smith, J. and LeMaire, G. (2024) ‘Smoothing the Way for CCUS’, World Cement, April 2024 Edition.  

By Simon ThomsenLeilac Chief Technology Officer

Hurdles to CCUS Adoption

It’s no secret the cement industry is difficult to decarbonise, the sector is hard-to-abate for many reasons. CO2 is an intrinsic feature of cement manufacturing. To capture CO2 successfully, a technology must operate in harmony within a complex set of interrelated systems, each affecting the other. Combustion systems are stabilised against waste heat recovery modules to minimise fuel use. Precise clinker processes ensure industry-standard product compositions. The control room oversees a balance between these systems. What’s more, this balance is unique to each cement plant, and each cement plant is different from the next. 

Carbon capture solutions traditionally involve large, rigid, and monolithic facilities. For a host plant, these new technologies can be difficult to integrate without disrupting operations. Some solutions impose a maintenance shutdown, to tie-in the apparatus as an ‘end-of-pipe’ installation, while others require extensive plant re-configuration and auxiliary equipment. Some CCUS technologies are only feasible for newly built, state-of-the-art plants. 

Perhaps the biggest hurdle to adoption, however, is the fact that none of these technologies have been proven beyond pilot scale. Given the challenges outlined above, a plant manager could be forgiven for hesitance – “Will this even work at our plant? Can we really afford it? Is any of this worth the commercial risk?”  

There has been a sustained and praiseworthy effort from the CCUS research and development sector to adapt conventional CCUS technologies and make them compatible with a cement plant’s process. Innovative design and extensive modelling from a broad pool of technology companies have led to demonstrations in operational environments. These are necessary milestones, and this work has brought CCUS for cement to its critical juncture. Now, the technology must be proven in its intended commercial context; for the host plants tasked with integrating these projects, it could well be a daunting prospect.  

The partial retrofit – A de-risked approach to integrating carbon capture 

De-risking carbon capture for the host manufacturer should be an industry priority. Operational concerns form a major barrier to CCUS’s acceptance in cement. If we want to see an increased uptake in these solutions, and a cleaner environment by proxy, then these technologies must be integrated in a way that is not disruptive to the producers absorbing them. CCUS solutions must be low risk, scalable and adaptable to the features of individual cement plants.  

One way of de-risking this integration process is to develop a technology that can be assimilated to the host plant’s process in incremental steps. By allowing the manufacturer to trial a CCUS solution, they can evaluate its suitability before fully absorbing it into their plant. Leilac’s core technology design facilitates this gradually integrated approach.  

Single Leilac Module depicted next to a typical preheater tower
A single Leilac module, depicted next to a typical preheater tower.

Say a mid-sized cement manufacturer wants to decarbonise one of their brownfield installations. Given their wariness of undermining production commitments, the plant wants to start by trialling a single Leilac module, containing four calciner tubes. This could equate to just 20% of this plant’s raw meal inventory. The other 80% would remain in the host plant’s established production stream. If, for any reason, the integration ran into difficulties, the consequences of this setback would be minimised. By lowering CCUS’s potential impact to production capabilities you, in turn, lower the commercial risk of adopting such technologies.  

And what if a CCUS technology could be integrated without extensive plant shutdowns? Commercial concerns aside, shutdown campaigns are a pain for the manufacturer, especially if it is tying in and commissioning a large and inflexible carbon capture facility. The host plant’s apparatus must be isolated, flushed and / or purged, broken into, re-configured, pressure assessed and re-commissioned. The risks associated with these operations to both personnel and equipment are significant in even the safest campaigns.  

By using a modular, potentially staged approach, Leilac seeks to reduce the operational commitment associated with CCUS. Leilac has designed its integration process to fit within a typical routine maintenance campaign. A calciner can be built in advance of the shutdown, erected beside the plant’s preheater tower and tied in to pre-selected auxiliaries, to reduce installation time.  

Scaling-up to suit 

The manufacturer should be able decide if or when they scale up their decarbonisation campaign. It is important this decision can be balanced against other operational priorities. Following a successful trial period, scaling up could begin immediately. Alternatively, scaling up can be scheduled to mirror broader decarbonisation ambitions or requirements, such as the phase out of free allowances under the EU ETS. A plant might balance their schedule against the expected local availability of CO2 transport and storage infrastructure. If this infrastructure is already in place, and the manufacturer wishes to decarbonise quickly, then a full-scale plant could be integrated immediately without a staged integration process. Making CCUS adaptable to the manufacturer’s priorities can help encourage industry-wide adoption.  

Leilac plant operating on alternative fuel (left) and electricity (right) at full scale
Comparing configuration options – a Leilac plant operating on alternative fuel (left) and electricity (right)
at full scale.

Returning to the brownfield integration scenario, let us say a Leilac calciner has successfully decarbonised 20% of the plant’s inventory. The manufacturer can then decide to increase their capture capabilities in further increments. Perhaps the plant wants to de-commission an aging pre-heater tower, with a view to eventually replacing it with a full-scale Leilac plant. The Leilac plant could be scaled up on a module-by-module basis, increasing its throughput in roughly 20% stages, dependant on plant size. The inventory routed to the pre-heater tower could be gradually dialled back, thus maintaining a stable production train during the integration process. 

Making CCUS fit 

Each cement plant has a unique site layout. A manufacturer will be concerned about the size and shape of the facility being built, and how that fits within available space.  

To address these concerns, the modular nature of the Leilac technology enables calciner tubes to be arranged in highly flexible configurations. Like a game of Tetris, modules can be long and thin, square, clustered together, arranged in an L-shape and constructed around existing equipment, including the rotary kiln. Furthermore, these modules can be stacked or conjoined depending on the hosts plant’s preference. A host plant that wanted to prioritise a smaller footprint could opt for a taller, stacked plant – 13 x 26 metres and a 100-metre tower height. Or, if the host plant had concerns about height, they could choose a wider, shorter option – 26 metres x 26 metres and a 60-metre tower height.  

Examples of Leilac’s furnace configuration options
Examples of Leilac’s furnace configuration options.

There is not a proportional relationship between a Leilac plant’s capture capacity and its footprint. As we go from one calciner tube at pilot scale, to a four-tube module at demonstration scale, to optimised multi-tube modules at full scale, more tubes can be incorporated into relatively smaller modules.  Replicating a module on site to double the capture capacity does not mean duplicating all ancillary systems either. If the Leilac plant was scaled-up from one module to five modules, then the CO2 could still be processed by a singular end-of-pipe compression unit.  

Scaling up with low carbon fuel optionality 

We aim to see Leilac’s technology integrated worldwide. This is why we have developed a technology that can run on a variety of energy sources, including electricity, alternative fuels, natural gas, solid fuels (such as coal & petcoke), biomass, and hydrogen. 

The availability, price, and carbon-intensity of a given fuel varies by region and fluctuates over time. When integrating a Leilac plant, fuel options can be customised depending on market conditions, resource constraints and the host plant’s operational priorities.  

The industry is trending away from heavy fuels, such as coal and petcoke, towards alternative fuels, such as municipal solid waste and biomass1. Future greenfield plans may look to electrify their processes for a future-proof, low-carbon fuel option. But what if a brownfield installation wants to trial a new fuel source? Perhaps there are concerns about a fuel’s effect on the plant’s flue gas stream. De-risking integration could encourage the adoption of alternative fuels as well.  

Leilac’s technology can integrate new fuel sources during the scaling up process. Given that our modules are compartmentalised, fuel sources can be trialled in a limited and partially isolated manner. Our technology facilitates the calcination reaction through indirect heat. If the tube’s temperature profile remains stable, then the reaction is not affected by fuel choice. Leilac-2, a replicable four-tube module, is designed to run with over 95% alternative fuel use. Other Leilac projects are developing full electric multi-tube modules.  

Host plants can opt for more than one fuel option to be available. If one of these options is electricity, the prospect of fuel switching based on market conditions opens potential additional revenue streams through load-balancing services to the grid.  

Leilac plant constructed above a rotary kiln
A Leilac plant constructed above a rotary kiln.

Leilac’s technology development continues to support its future vision, including the development of suitable materials handling solutions and combustion solutions that enable 100% alternative fuel use at full-scale. More details on these solutions to enable low-cost CO2 capture at scale will be made available in upcoming publications. 

Tortoise beats hare 

There is a sense of urgency. The cement industry has pledged to reach net-zero emissions by 2050, and to achieve that, the GCCA expects 1.4Gt of CO2 will need to be captured annually. This means that over 1 million tonnes of CO2 capture capacity for cement must be brought online, each week, between now and 2050. This is not the time for industry hesitation. By de-risking integration and providing the manufacturer with customizable options and scalability, you can remove the sources of this hesitation. While we must act as quickly as possible if we are to reach these targets, paradoxically, a gradual and scalable approach may be the fastest way to decarbonise cement.