Concrete and CO2

What will we do about concrete? The production of it produces nearly as much global CO2 (10%) as residential heating and electricity usage (11.3%).[1] As a member of the American Society of Mechanical Engineers, I understand that this may be one of the more difficult problems to solve in the climate area. Unlike energy production, which simply requires scaling up known solutions to clean energy, there is no known solution to the dilemma caused by the flexible and ubiquitous building material. Both the byproduct of its production and the massive energy production requirements are large causes. Further, it produces a massive heat island (it absorbs heat) and inhibits percolation. The average city is estimated to be 10 degrees warmer than a century ago due to the heat island effect of concrete and asphalt.

The building construction industry uses large amounts of concrete. China alone used 6.6 billion tons of concrete during its building spree between 2011 and 2013 than the USA used in the entire 20th century. Each ton of cement, mainly due to clinker, creates 900 kg of CO2, which is roughly 7- 15% of concrete. If one used the process of Blue Planet of Los Gatos, CA to convert flue gas to aggregate for the concrete mix, the net process can be carbon neutral or even negative.[1] We can support and encourage such practices, using potentially damaging byproducts in a useful manner.

The best thing that you can do is send an engineer to the CA legislature that can stick to the issues, and understand this conundrum well enough to formulate the plans and support that industry and academia need to generate cost-effective solutions and choices. We have been using cement and concrete for two millennia and this is not an easy problem.

SF Skyline of Concrete


[1] R. P. Siegel, Low Carbon Concrete can fight Global Warming, ASME, Feb. 18, 2020

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