A team of scientists from the UK say that the secret to producing zero emissions cement has finally been cracked
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It would be no exaggeration to say that our world would be a very different place indeed without cement and concrete. Together they are the materials from which our homes, offices, shops, roads, damns and other buildings are constructed. They are easily the most commonly used man-made materials on Earth.
Cement, which is a key ingredient of concrete, is vital to our lives, yet it comes with a very heavy environmental footprint. The production of cement contributes roughly 7-8 per cent of the world’s total annual carbon emissions. Indeed, it’s said that if the cement industry were a country it would rank as the world’s fourth largest green house gas (GHG) emitter after China, the USA, and India. But, with the worldwide demand for concrete soaring it’s likely that the construction industry’s carbon footprint will grow even larger.
This has made finding an environmentally friendly replacement for cement one of the key challenges to lowering global emissions. While there are already ways of making cement with reduced emissions, most are too expensive or difficult to deploy at scale, rely on unproven technologies, or don’t come close to zero emissions.
But now, in what could be a significant advancement, a team of scientists from the UK’s University of Cambridge think they may have created the world’s first-ever zero-emissions cement.
Writing this week in the journal Nature, the team say they have pioneered a method that tweaks an existing process for steel manufacturing to produce recycled cement without the associated CO2 pollution. To do this, they substituted a key ingredient in the steel manufacturing process with old cement sourced from demolished buildings. Instead of waste being produced, the end result was recycled cement ready for use in concrete, bypassing the emissions-heavy process of superheating limestone in kilns.
According to Professor Allwood, one of the members of the research team, the key to this being an emissions-free process is to ensure that the electricity required to heat the furnaces comes from renewable sources. ‘Once the electricity has no emissions, then our process would have no emissions,’ he said.
The International Energy Agency (IEA) has said that if emissions from the cement industry continue to increase, a pledge of carbon neutrality by 2050 will almost certainly remain out of reach. Referring to this, Prof Allwood went on to say: ‘This could be a turning point in the journey to a safe future climate. Combining steel and cement recycling in a single process powered by renewable electricity, this could secure the supply of the basic materials of construction to support the infrastructure of a zero-emissions world and to enable economic development where it is most needed.’
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