Wall Street Journal – March 12, 2024 – Concrete accounts for more than 7% of global carbon emissions, according to some estimates. That is roughly the same as the CO2 produced by all of India and more than double the amount produced by the global aviation industry.
Most of those emissions are caused by cement, the glue that binds together sand and gravel to make the concrete used to build roads, bridges and tall buildings.
Concrete, the second-most-used material in the world after water, is popular because it is cheap, relatively easy to produce, fire-resistant and extremely strong.
“It’s the most democratic material,” said Admir Masic, an associate professor of civil and environmental engineering at the Massachusetts Institute of Technology.
It is also very, very dirty. Cement is made by heating limestone and clay at around 2,700 degrees Fahrenheit in giant kilns and turning them into marble-sized granules called clinker, which are then turned into a powder and mixed with other materials. As it heats up, the limestone releases a lot of CO2, and the whole process is often powered by fossil fuels such as coal or gas.
Former NBA star Rick Fox, Jeff Bezos and Bill Gates are part of a wave of investment looking to turn one of the world’s worst pollutants green. Getty Images, Associated Press, Reuters
Big cement producers and startups including Brimstone and Partanna, a startup based in the Bahamas and headed by three-time NBA champion Fox, are developing new technologies to produce cement while producing less CO2. Breakthrough Energy Ventures, which was founded by Gates and is backed by Bezos, Jack Ma and Michael Bloomberg among others, Fifth Wall and other venture firms have poured tens of millions of dollars into these companies.
These companies are being motivated in part by the federal government, which is dishing out grants and setting aside billions to decarbonize materials such as cement. Local regulators are also encouraging these new technologies. California in 2021 passed a law to cut emissions from cement and New York in 2023 issued rules that limit emissions on concrete used in state-funded construction projects.