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The Paris Agreement provided the clear objective of keeping a global temperature rise of below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to below 1.5 °C. This has been supported by widespread government and industrial commitments for carbon neutrality by 2050.
This however is not an easy commitment to reach for certain sectors. Cement for example is the key ingredient in concrete, the most widely used man-made material on the planet.
“Cement is the safe, affordable bedrock of our civilisation,” explains EU-funded LEILAC project coordinator Daniel Rennie, general manager of cement decarbonisation at Calix Europe, France. “It is used in our roads, buildings, homes, offices and almost all our infrastructure.” Lime, a calcium-containing material, is also used in a variety of applications including iron and steel, chemical, paper, food and farming.
Despite achieving production efficiencies in recent years, both industries are responsible for 8 % of all global CO2 emissions. These emissions are released when limestone used in the manufacturing process is heated. Capturing this CO2, and ensuring that it does not reach the atmosphere, is the only means of stopping these emissions.
Successful carbon capture
To address this challenge, the EU-funded LEILAC project has developed new technology that offers producers a low-cost method of reducing atmospheric emissions. The ‘Calix’ process, as it is called, works by heating limestone via a special steel reactor. This enables pure CO2 to be separated and captured as it is released from the limestone, keeping the furnace exhaust gases separate.
“Unlike other capture technologies, the new process does not involve any additional processes or chemicals,” says Rennie. “It is therefore a very low-cost way of capturing unavoidable CO2 process emissions.”
A pilot plant at the HeidelbergCement plant in Lixhe, Belgium was built to investigate whether Calix’s novel process could effectively be applied to the cement and lime sector. “Initial trials have been extremely promising,” adds Rennie. “The technology is working as expected.”
While still to be pushed to full capacity, the pilot is designed to separate CO2 at a rate of around 18 000 tonnes per year, the equivalent to the annual emissions of around 10 000 cars.
Transition to global decarbonisation
The success of the LEILAC project has opened the door to a successor project, LEILAC2. This will apply the Calix technology at a larger scale to an operational cement plant, aiming to capture 20 % of its emissions. This works out at around 100 000 tonnes per year, the equivalent to the annual emissions of around 55 000 cars.
“If successful, the aim is for this technology to be applied at full-scale globally over the coming years, to contribute towards decarbonisation efforts,” says Rennie. “The cement and lime industries are very interested in pursuing all available decarbonisation pathways.”
Finding low-cost and effective solutions is crucial, not only because of the sector’s primary importance to a raft of industries, but because of its economic significance to the main regions in Europe.
“The production of cement and lime directly employs more than 384 000 people in Europe,” notes Rennie. “Combined with indirect jobs, this comes to more than 1 million. Our aim is to protect local economies, whilst supporting a transition towards global decarbonisation.”