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The construction industry is one of the largest and most active heavy industries in the world today. The industry can play a huge role in the mission to tackle climate change and protect the planet and its ecosystems.
A significant proportion of this harm is caused by the manufacture and use of cement – the setting and hardening ingredient in concrete, which is favored by developers around the world for its low cost, strength, and range of structural applications.
Cement is second only to water as the most consumed resource on the planet, and finding ways to manufacture it with minimal environmental damage is an imperative green technology solution.
A paper published this year in Proceedings of the National Academy of Sciences of the United States of America (PNAS) discusses the role of cement manufacture in green technology (Schneider, 2019).
The author, Jacob Schneider of mission-based carbon dioxide mitigating start-up Blue Planet Ltd., discusses various proposals recently put forward to “decarbonize” construction – or to reduce as much as possible the industry’s emissions of harmful carbon dioxide (CO2) into the planet’s atmosphere.
Schneider positioned these proposals in light of “a movement of local, state, federal, and even international legislation that seeks to do something proactively about the increasing CO2 concentration in Earth’s atmosphere”. This movement is putting increasing pressure on industries to help address climate change by actively seeking out ways to minimize their reliance on carbon emissions.
Problems with Cement
Schneider reports that annual CO2 emissions are in “the order of billions of metric tons”, and that steel plants, aluminum manufacture and cement plants are some of the “most prominent” industrial emitters.A focus on cement manufacture – which as Schneider reports represents over 5% of annual global CO2 emissions – is crucial.
The problem with cement is that it typically requires the burning of large amounts of fossil fuels to keep a high-temperature kiln burning. This is necessary to bring about the calcination process of limestone (CaCO3) and other raw materials. Not only are significant levels of CO2 emitted in the burning of fossil fuels to heat the kiln, but they are also released when CaCO3 decomposes in the kiln.
Green Technology Solution
One of the solutions that Schneider discusses is a proposal for cement manufacture that would replace the need for fossil fuels with a renewable energy electrochemical process. This research, which was also published in PNAS, includes a proposal and proof of concept for using neutral water electrolysis to decarbonate CaCO3 in preparation for Portland cement manufacture (Ellis et al., 2019).
This would not only reduce the need for burning large amounts of fossil fuels to heat the kiln but would also produce useful byproducts that can be used to close the loop in cement manufacture so that it could be entirely powered by renewable energy.
Cement manufacture can become a green technology – one which, along with many other changes to green technology, would help to cut down on global CO2 emissions. That paper puts the impact of cement manufacture much higher than in Schneider’s article, at approximately 8% of worldwide emissions of CO2.
Many Solutions Needed
This is one of many green technology solutions put forward by scientists to minimize the harmful effects of cement manufacture on the planet and its ecosystems. Other proposals include “carbon capture from flue gases, use of alternative fuels, or development of supplementary cementitious materials” (Ellis et al., 2019).
Continual investment and development is required to bring these to fruition. Hopefully, the legislative regimes outlined by Schneider, dedicated focuses of researchers, and demands of an increasingly environmentally conscious public will drive this push towards a green new world.
References and Further Reading
Ellis, L.D., Badel, A.F., Chiang, M.L., Park, R.J.-Y. and Chiang, Y.-M. (2019) Toward electrochemical synthesis of cement—An electrolyzer-based process for decarbonating CaCO3 while producing useful gas streams. Proceedings of the National Academy of Sciences, p.201821673. https://doi.org/10.1073/pnas.1821673116
Schneider, J. (2019) Decarbonizing construction through carbonation. Proceedings of the National Academy of Sciences, p.201913867. https://doi.org/10.1073/pnas.1913867116