Energy Efficient Low-Carbon Cement is Here
Breakthrough technologies often spend years in development before offering something of value for businesses. But Nuada, a new carbon capture system from MOF Technologies bucks that trend. In this article, Dr Jose Casaban explains why it represents a step-change for the production of low-carbon cement.
The cement industry faces an intractable problem. It’s well-known that concrete accounts for 2.8 billion tonnes of CO2 emissions each year, equivalent to roughly 8% of the global total and a greater share than any country other than China or the US. But it’s also one of the world’s most-consumed resources, second only to water, and essential for virtually every building project, not least key civil infrastructure. Yet, there’s no viable alternative, leaving economic stability and climate targets in the balance.
This isn’t another article imploring the industry to change its ways. Everyone reading this will be keenly aware that decisive action is needed to bring emissions in line with ambitious targets, especially when legislation and impending changes to the carbon tax credits scheme effectively force a new approach. The focus of this piece is instead on solutions, and in particular a new system called Nuada that can be seen as a legitimately game-changing moment for carbon capture. CCUS – carbon capture, utilisation and storage – is widely seen as one of the best methods for industry to cut emissions in ‘hard-to-abate’, and yet essential, sectors like cement production. It gives businesses a practical means to tackle their carbon footprint while also maintaining the level of output needed to meet global demand. It’s not without its challenges but currently offers the most viable and fastest route to a more sustainable future. As the International Energy Association points out: “Key strategies to cut carbon emissions in cement production include improving energy efficiency, switching to lower-carbon fuels, promoting material efficiency (to reduce the clinker-to-cement ratio and total demand) and advancing process and technology innovations such as CC.” The latter two contribute the most to direct emissions reductions in the IEA’s net zero by 2050 scenario. Efficiency Has Been Lacking Carbon Capture (CC) is hardly a new concept for the industry and many are aware of the significant emission reductions it can deliver. The Global Cement and Concrete Association (GCCA), for example, recently laid out a carbon reduction roadmap on behalf of 38 major producers across the world. CC has a central role in the plan, with its authors suggesting that 36% of the industry’s emissions can be addressed directly by CC technology – a huge saving when considering the 2.8 billion tonnes emitted every year. The GCCA concludes by emphasising the need to “bring forward the required breakthrough technologies to be ready for commercial-scale deployment” by the end of the decade. "36% of the industry’s emissions can be addressed directly by CC technology – a huge saving when considering the 2.8 billion tonnes emitted every year." The roadmap’s aims are commendable, though the idea of commercial-scale deployment has been an ongoing challenge that few businesses have been able to overcome. Some might suggest this is a convenient excuse for the cement industry to continue down the same path, but that argument belies the GCCA’s decision to make significant, lasting changes before 2030. Even the Global CCS Institute admits a current lack of convincing business incentives are among the biggest barriers to the technology becoming standard practice across heavy industry. It's not surprising the CCS Institute has drawn this conclusion. There’s a long list of carbon capture technologies that are, in theory at least, ready to help cement producers, such as oxyfuel combustion and chemical looping. Yet few have been tested at scale in the field. The only technology that has achieved this so far is amine gas treatment, sometimes called ‘carbon scrubbing’, which requires a series of separators at different processing stages. Getting this infrastructure in place can be disruptive, not to mention expensive if it hasn’t been costed-in when a facility is first designed. But that’s not the biggest problem. The commercial risk when using amine is only made worse by the high amounts of energy required when using it to strip CO2 from a gas stream. One 2020 study from the Carbon Science and Technology Institute found that regenerating solvent on its own contributes 50%-80% of the total energy requirement – and that’s before any other processes are factored in. These solvents are also corrosive, can be chemically unstable and lead to further environmental complications due to subsequent amine leakage. These issues not only hit a business’s bottom line but also further complicate CC, making it harder to convince decision-makers that it’s actually worth pursuing in the first place. "Regenerating solvent on its own contributes 50%-80% of the total energy requirement – and that’s before any other processes are factored in." Breakthrough The difficulties around amines will soon prove negligible as newer methods of CC begin to replace them. Solid sorbent technologies, and in particular MOFs (metal-organic frameworks), hold the greatest potential for low-carbon cement production as they can deliver significant emissions savings without having to reimagine the industry’s business model from the ground up. MOFs are highly engineered filters that use bespoke chemistry to target, capture and remove specific gases like CO2. It’s this selectivity combined with an ability to release with minimal energy input that gives them such promise – not least for heavy industry where cost-effective CC is now sorely needed. Nuada, a system that has been developed by the team at MOF Technologies, has broken new ground in this area, with a legitimate game-changing method for CC ideally matched to cement production. Nuada’s unparalleled performance is driven by vacuum pressure swing adsorption technology coupled with a MOF-based filter that has been specifically designed to capture and remove CO2. With this system, existing plants don't need to be redesigned and the technology can work independently of, or be combined with, cement reformulation strategies. The environmental hazards associated with amines are also avoided. It sounds fanciful but, when deployed correctly, this technology can give manufacturers a credible way to maintain current outputs while also meeting the obligations of business in a net zero era. "When deployed correctly, this technology can give manufacturers a credible way to maintain current outputs while also meeting the obligations of business in a net zero era." Beyond energy efficiency, Nuada has also addressed some of the practicalities that have troubled other methods of CC. Unlike traditional approaches using amines, this new system is modular, meaning it can be easily connected to a facility’s waste gas line without extensive redesign or installation work. The units can then be scaled according to demand, giving concrete production a non-invasive and far more cost-effective means to capture CO2 at source. This kind of flexibility has been sorely needed, particularly throughout the last three years where market demand has fluctuated.
The system is deceptively simple but the results speak for themselves. MOF Technologies has shown users can reduce the amount of energy used for CC by an average of 80%, not to mention save money by adopting a ‘plug and play’ solution that bypasses the financial burden found with so many alternative technologies. MOF-based approaches also make the process of isolating CO2 more straightforward, allowing it to be redirected back into the concrete formation process. Perhaps the biggest boon, however, is a capture cost as low as $16 per ton of CO2. This is virtually unmatched by current standards, providing the crucial first step for unlocking other parts of the CCUS value chain. Businesses could, for example, valorise their surplus CO2 into high value chemicals and fuels and sell them on to secondary markets for a profit. "Perhaps the biggest boon, however, is a capture cost as low as $16 per ton of CO2." These are the kinds of opportunities that will convince investors and help CC become standard practice in a sector that recognises the need for change. Nuada’s system cannot solve all of the challenges associated with CCUS, but it will ease some of the bottlenecks and, crucially, offer businesses a credible route towards a more sustainable future.
Find out more about Nuada carbon capture technology