Recent research published in the journal “Green Energy and Resources” highlights promising advancements in the field of ex-situ CO2 mineralisation, a process that transforms carbon dioxide into stable carbonates by reacting it with industrial solid waste. This study, led by Song Zhou from CSIRO Energy in Australia, addresses two pressing global challenges: rising atmospheric CO2 levels and the increasing burden of solid waste.
The study emphasizes the need for sustainable and recyclable chemicals in CO2 mineralisation, particularly in light of concerns about the extensive use of traditional chemicals. One of the key findings is the potential of trapping and recycling ammonia gas, which can enhance the efficiency of CO2 mineralisation when using ammonium salts. This could open up new pathways for industries looking to reduce their carbon footprint while managing waste.
Additionally, the research suggests that scaling up the use of amines in mineralisation processes could be viable if conventional stripping methods are replaced with dedicated mineralisation units. However, this shift depends on overcoming technical challenges, such as the leaching capacity of amines and their limited use with certain solid feedstocks that contain water-soluble calcium or magnesium compounds.
Another innovative approach discussed in the paper involves amino acids, which, due to their unique zwitterionic structures, can provide satisfactory CO2 mineralisation efficiency at low temperatures while maintaining good recyclability. This could appeal to various sectors, including agriculture and pharmaceuticals, where amino acids are already in use.
The research also introduces a novel HCl regeneration technology known as ‘oxy-pyrohydrolysis.’ This method allows for simultaneous CO2 mineralisation and HCl regeneration in a single step, showcasing the potential for integrated solutions in carbon management.
However, the study notes that operational costs could remain high when employing recyclable chemicals, particularly at elevated temperatures. To mitigate these costs, the authors recommend exploring energy optimization strategies, such as the use of low-energy chemicals and the integration of waste energy harvesting units.
Zhou states, “This review paper aims to delineate potential avenues for cost-effective CO2 mineralisation facilitated by recyclable chemicals, thereby alleviating post-processing costs and environmental concerns associated with chemical residues.” This focus on cost-effectiveness and sustainability presents significant commercial opportunities for industries engaged in carbon capture and utilization (CCU), as well as those dealing with alkaline solid wastes.
As industries increasingly seek sustainable solutions to combat climate change, the findings from this research could pave the way for more effective and economically viable methods of CO2 mineralisation, ultimately contributing to permanent carbon storage and a reduction in environmental impact.
