Cement production and emissions from to Source: Analysis of Olivier et al. China also has high levels of cement production in per capita terms, as it experiences rapid urbanisation , with many people moving to high- or low-rise buildings made from cement.
However, Chinese consumption may be close to levelling off. Most future growth is expected to happen in India and other emerging markets. Man lifting pan with cement onto a scaffold, Punjab, In Europe, existing kiln facilities are capable of meeting future demand for cement, according to Chatham House.
European cement producers are also some of the most advanced in terms of their use of alternative fuels, it adds. However, older equipment puts them behind India and China on energy efficiency. Likewise, the US, the fourth-largest cement consumer, lags behind other major producers in terms of energy efficiency and its clinker ratio.
Progress so far has come in three main areas. First, more efficient cement kilns have made production less energy-intensive. Second, use of alternative fuels has also lowered emissions — for example, using biomass or waste in place of coal. Third, reducing the proportion of Portland clinker in cement has also cut emissions.
Clinker can be substituted with other cement-like materials, including waste from coal combustion and steelmaking. The world average clinker ratio clinker:cement fell to 0. This is because energy efficiency improvements were offset by a slight increase in the clinker ratio, it says. Nevertheless, overall cement emissions were flat or declining in recent years as demand in China levelled off. BioMason uses bacteria to grow cement bricks which it says can sequester carbon.
Three of these are the strategies previously being pursued by the cement industry to limit emissions, namely, improved energy efficiency, lower-emission fuels and lower clinker ratios.
For example, the roadmap sets a target average global clinker ratio of 0. This has not yet been used in the cement industry bar trials , but the roadmap assumes integration of CCS in the cement sector reaches commercial-scale deployment by Uncertainty over the potential to rapidly scale-up CCS and its large cost are major barriers to its use in reducing concrete emissions. It says:. These also become more critical if CCS proves too challenging to scale. If these could rival the cost and performance of Portland cement, they would offer a way to significantly reduce emissions.
However, none have yet achieved large-scale commercial use and are currently used only in niche applications. Moreover, innovation in the sector tends to focus on incremental changes, a global patent search by Chatham House shows, with a limited focus on novel cements.
Geopolymer-based cements, for example, have been a focus of research since the s. These do not use calcium carbonate as a key ingredient, harden at room temperature and release only water. If this CO2 absorption can be made higher than CO2 released during their production, cements could potentially be used as a carbon sink.
Credit: Solidia. The firm is now in a partnership with major cement producer LafargeHolcim. However, the firm failed to raise sufficient funds to continue research and production. Other firms are using completely different materials to make cement. He is the James R. Duo Zhang does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
One of the big contributors to climate change is right beneath your feet, and transforming it could be a powerful solution for keeping greenhouse gases out of the atmosphere. Concrete is one of the most-used resources on Earth, with an estimated 26 billion tons produced annually worldwide.
Given the scale of the industry and its greenhouse gas emissions, technologies that can reinvent concrete could have profound impacts on climate change. That includes CO2-infused concrete that locks up the greenhouse gas and can be stronger and even bendable.
The industry is ripe for dramatic change, particularly with the Biden administration promising to invest big in infrastructure projects and cut U. However, to put CO2 to work in concrete on a wide scale in a way that drastically cuts emissions, all of its related emissions must be taken into account.
Concrete is made up of aggregate materials — primarily rocks and sand — along with cement and water. Industrial byproducts such as iron slag and coal fly ash are now frequently used to reduce the amount of cement needed.
The resulting concrete can have significantly lower emissions because of that change. Alternative binders, such as limestone calcined clay , can also reduce cement use. Apart from developing blended cements, researchers and companies are focusing on ways to use captured CO2 as an ingredient in the concrete itself, locking it away and preventing it from entering the atmosphere.
CO2 can be added in the form of aggregates — or injected during mixing. Carbonation curing , also known as CO2 curing, can also be used after concrete has been cast. Later, the Romans were known to be masters of cement and concrete, building the Pantheon in Rome in AD, with its 43m-diameter free-standing concrete dome the largest in the world. But the concrete used in our modern-built environment owes much of its make-up to a process patented in the early 19th Century by bricklayer Joseph Aspdin of Leeds.
His new technique of roasting limestone and clay in an oven and then grinding it to a powder to make "artificial stone" is now known as Portland cement - still the key ingredient in almost all modern concrete. But, despite its ubiquitous presence, concrete's environmental credentials have come under increased scrutiny in the last couple of decades. Not only does the production of Portland cement involve quarrying - causing airborne pollution in the form of dust - it also requires the use of massive kilns, which require large amounts of energy.
The actual chemical process of making cement also emits staggeringly high levels of CO2. Chief executive Benjamin Sporton says the fact the organisation now exists "is a demonstration of the commitment of the industry to sustainability, including taking action on climate change". The GCCA is due to publish a set of sustainability guidelines, which its membership will have to follow. But despite the promise, Chatham House argues that the industry is reaching the limits of what it can do with current measures.
If the sector has any hope of meeting its commitments to the Paris Agreement on climate change, it will need to look at overhauling the cement-making process itself, not only reducing the use of fossil fuels. It is the process of making "clinker" - the key constituent of cement - that emits the largest amount of CO2 in cement-making.
In , world cement production generated around 2. More than half of that came from the calcination process. Because of this, Mr Preston and his colleagues argue the sector urgently needs to pursue a number of CO2 reduction strategies. Further efforts on energy efficiency, a move away from fossil fuels and pursuing carbon capture and storage will help, but can only do so much. What the industry really needs to do is plough efforts into producing new types of cement, he argues. In fact, low-carbon cements and "novel cements" might do away with the need for clinker altogether.
One of those trying to drum up greater support for such alternative cements is Ginger Krieg Dosier, co-founder and CEO of BioMason - a start-up in North Carolina that uses trillions of bacteria to grow bio-concrete bricks.
The technique, which involves placing sand in moulds and injecting it with microorganisms, initiates a process similar to the one that creates coral. The discovery led her to create her own solution, which, after years of development, now takes only four days. It happens at room temperature, without the need for fossil fuels or calcination - two of the main sources of the cement industry's CO2 emissions.
Ms Krieg Dosier believes green cements and technologies such as hers offer a solution to the sector's emissions issue. Alongside such alternative cements, other "disruptive" forces are also beginning to drive change. Digitalisation, machine learning and an increasing awareness of sustainability are all having an impact on the cement industry's culture. But changing processes quickly enough to meet the cement industry's obligations will be a challenge. The sector is dominated by a small number of major producers who are reluctant to experiment or change business models.
Architects, engineers, contractors and clients are also, rather understandably, cautious about using new building materials. But, with very few low-carbon cements reaching commercialisation, and none being applied at scale in an industry where bigger and taller is often the ambition, it looks likely that sustained government support will be needed. Without governments applying pressure on the industry or providing funding, it may not be possible to get the next generation of low-carbon cements out of the laboratory and into the market within the required timescale.
The Intergovernmental Panel on Climate Change - the leading international body on global warming - last month argued the global average temperature rise needed to be kept below 1.
Like other young companies, Ms Krieg Dosier describes the difficulties of simultaneously developing and marketing her products and scaling up manufacturing processes to compete within the wider construction industry.
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