Carbon capture, utilisation and storage (CCUS) describes processes that capture CO2 emissions from industrial sources and either reuses them in other industrial processes or stores them for centuries or millennia so that they will not enter the atmosphere. CCUS is a crucial solution for the cement sector where a large share of emissions are not energy related but due to the specific chemistry of cement making.
CCUS is a cornerstone of the net zero carbon roadmap for cement and concrete. The technology has been shown to work and is close to maturity but an industry-wide roll out of CCUS will require close cooperation between the industry, policymakers and the investment community.
While the technology is advancing, the economics remain challenging. The development of a ‘carbon economy’ is therefore an essential step in the move from a number of successful pilots across the world to widespread and commercial scale deployment. An essential part of this journey will be the re-evaluation of CO2 as a usable commodity rather than a waste product.
CO2 capture is still expensive today, but technology is improving and the significant number of demonstration facilities, currently being deployed in cement production, demonstrates the potential for significant cost reduction in the years ahead.
A variety of different capture technologies are currently being tested in pilot projects across the globe. These include post combustion (e.g. chemical absorption by amines), direct separation, oxyfuel and calcium looping. Typically additional energy is needed for these technologies to operate the CO2 separation and handling processes.
Utilisation (or Valorisation)
Captured CO2 can be used in the production of e-fuels and as a feedstock for the chemical industry. More specific uses are to promote crop growth in greenhouses and in the food and drinks industries.
The construction industry can also play its part in developing an economy for CO2 – and there are signs that this is happening. The process of carbonation has been long understood by engineers with respect to reinforced concrete and is rightly limited for the sake of durability. Recent development has focused on speeding up the reaction in various applications as a method of sequestering CO2. Potential applications include:
• the manufacture of artificial aggregates
• curing concrete
• carbonation of recycled concrete.
CO2 can be sequestrated in geological formations which would avoid it being released into the atmosphere.
Both solutions, utilisation or sequestration, require the development of infrastructure between the source and point of use or storage.