Since its invention 199 years ago in England, Original Portland Cement (OPC) has become a critical building block for modern civilisation’s infrastructure. However, despite advancements in reducing emissions produced in cement production, it still makes up as much as 8% of global CO2 emissions. Therefore, it is currently a significant contributor to climate change. As we move towards net-zero targets and a sustainable future for construction, it is essential that the industry addresses this issue using a multi-pronged approach. The industry has already taken early joint action and has reduced absolute direct and indirect emissions by 53% since 1990, however there is still a long way to go [1].
There are two main barriers to reducing the emissions produced by making cement. Firstly, the fuels needed to power production and secondly, the chemistry of the process itself. Decarbonising the energy source is theoretically a simple part of the solution, through the use of renewable energy such as hydrogen or clean electrical energy. However, as Rick Gould writes in the latest edition of IEMA’s Transform Magazine, this can only have a limited affect:
“The problem is that CO2 is a by-product of calcination, a process where calcium carbonate is transformed into calcium oxide. Therefore, changing to carbon free fuels such as hydrogen still means up to 60% of the CO2 emissions would remain, owing to the chemistry of limestone.” [2]
To improve the process further a holistic approach to making concrete production more sustainable is needed. One part of this could be via alternative raw materials. A company called Brimstone is leading the way in using carbon-free feed rock, that results in a reported 60% decrease in emissions from the outset, whilst maintaining performance of the final product. A study conducted by RMIT University (Australia), discovered that biochar (produced from used coffee grounds) can replace up to 15% of sand typically used in the process. Used coffee grounds makes up a sizeable proportion of food waste globally and is therefore a readily available and largely untapped resource. The use of biochar could reduce landfill waste and reduce the amount of natural sand used in the industry. It also vastly increases the strength of the final product, by about 30%. Carbon Capture, Utilisation and Storage (CCUS) via post-combustion amine is also a promising method for reducing emissions. One cement plant in Norway is building a full-scale amine CCUS facility that will capture approximately 400,000 tonnes of CO2 from combustion waste gases per year.
We recognise here at SHIFT that embodied carbon of building materials and whole life carbon of structures is becoming an increasing area of focus for many banks and a variety of stakeholders. This is reflected in our updated SHIFT 2023 Environmental Assessment which asks our landlords to start engaging their supply chain on embodied carbon by reporting the volume of each material used in construction and maintenance works. At present this information has been difficult to obtain, but this is an emerging area (particularly for ESG reporting) and we hope that by starting to ask the questions now this will assist us in building a database of embodied carbon figures for typical archetypes. If you would like help in calculating your embodied carbon, get in touch with us here at SHIFT Environment.
Photo by Claus Grünstäudl on Unsplash
[2] IEMA, 2023. Transform Magazine Oct/Nov 2023 Edition. Page 26-27.