Making Concrete Green
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Concrete is the second most used substance in the world after water, and it accounts for seven percent of global carbon emissions. That is roughly the same amount of CO2 produced by India. Large amounts of carbon dioxide are released when limestone and clay are super-heated to make cement, the glue that binds the sand and gravel together to produce concrete. This process is often powered by fossil fuels like gas and coal.
Driven by federal grants and state emission standards, a number of startup companies are developing technologies and techniques to produce cement with low or no CO2 emissions. Brimstone, for example, asserts that it can make cement from rocks that contain no carbon, while Partanna claims it can produce cement with less CO2. Eco Material Technologies sells coal and volcanic ash substitutes that reduce the amount of cement in concrete. Canadian startup CarbonCure Technologies has developed a process to pump the CO2 from the cement process back into the concrete. Many companies in the green cement business face challenges to make their products and processes cost-effective, and some have not yet built scalable factories. Nevertheless, cement makers have no choice but to continue to search for cheap ways to cut pollution.