With carbon capture and storage (CCS) technologies gaining more attention as a possible solution to mitigate climate change, new research provides an unexpected approach: crushing rocks. Scientists have discovered that the carbon dioxide emitted during the normal crushing process of rocks commonly used in construction can be captured by conducting the process in CO2 gas. The researchers estimate that around 0.5% of global carbon emissions could be captured through this method. This could be a significant contribution to reducing greenhouse gas emissions, especially since construction is one of the largest global industries, accounting for a significant portion of carbon emissions. While further research is needed to fully explore the feasibility of this approach, the findings offer an intriguing possibility for carbon capture.
Scientists have discovered a promising new approach to carbon capture, according to a paper published in Nature Sustainability. The research suggests that almost no additional energy would be needed to capture carbon dioxide emissions during the normal crushing process of rocks commonly used in construction. The amount of CO2 that could be captured is estimated to be around 0.5% of global emissions, which is equivalent to planting a forest of mature trees the size of Germany.
The materials and construction industry is responsible for a significant portion of global carbon emissions, accounting for around 11%. Despite this, current crushing processes used in construction and mining do not capture CO2. Over 50 billion tons of rock is crushed globally each year, making this an important area for reducing emissions. Previous research has explored trapping carbon into single minerals using a similar method, but this has been found to be unstable and dissolves out of the mineral when placed in water.
The paper in Nature Sustainability documents how a larger proportion of carbon dioxide can be trapped in a stable, insoluble form in rocks composed of multiple different minerals by grinding them in CO2 gas. The resulting rock powders can then be stored and used in the environment for construction and other purposes. This could be a significant step towards reducing emissions from the construction industry.
The 0.5% figure was calculated for Norway as an example because the country publishes annual data on the volume of hard rock aggregate produced for their construction industry, as well as their annual national CO2 emissions. However, some countries, such as Australia and South Africa, produce far more waste rock due to their large mining industries. The researchers believe that if this technology were adopted worldwide in aggregate production, it could potentially capture 0.5% of global CO2 emissions—equivalent to 175 million tons of carbon dioxide annually.
Principal investigator Professor Rebecca Lunn, from the Department of Civil & Environmental Engineering, hopes that the sector could reduce emissions by adapting current setups to trap carbon from polluting gas streams such as those from cement manufacture or gas-fired power stations. She also notes that there are many industries for which there is currently no low carbon solution, and this research could allow direct gas capture of CO2 to decarbonize industries where a solution will not exist by 2050.
Co-investigator Dr. Mark Stillings added that the next step is to optimize the process and understand how it can be scaled up from the lab to industry. If this process is applied, it could greatly reduce the CO2 footprint associated with building houses and public infrastructure, helping to meet global objectives to combat climate change. As part of the Paris agreement, countries around the world have agreed to reduce their greenhouse gas emissions to net zero by around 2050 to limit global warming to well below 2 degrees Celsius.
Dr. Lucy Martin, Deputy Director for Cross Council Programmes at the Engineering and Physical Sciences Research Council (EPSRC), called the research “truly revelatory,” and highlighted its potential to significantly reduce global carbon emissions and help meet net zero goals. In the future, the researchers hope that the rock used in concrete to construct high-rise buildings, roads, bridges, and coastal defenses will have undergone this process and trapped CO2 that would otherwise have been released into the atmosphere and contributed to global temperature rise.
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