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Cement Sequesters CO₂: Wouldn’t it be lovely?

Cement is one of the most carbon emissions intensive parts of today’s buildings, and more often than not, one of the most widely used materials in pure mass per unit of floor area. Cement manufacturing is estimated responsible for 5% of global CO₂ emissions.

California has placed the reduction of carbon emissions from concrete high on its agenda to meet its ambitious CO2 emission reduction goals. Wouldn’t it be lovely if concrete could actually store CO2 instead of being responsible for so much CO2

Next to one of the largest fossil fuel-fired power plants in the United States, at Moss Landing on the Monterey Bay, Calera is capturing CO2 from the power plant and using it to make cement. Calera founder Brent Constantz claims that each ton of Calera cement contains half a ton of CO2 transformed into an essential ingredient of cement. Constantz says his process is probably the best carbon capture and storage technique available.

Calera bubbles the CO2 through seawater to make calcium carbonate. The resulting water has the calcium and magnesium removed, making it even more suitable for desalination. Local agriculture in the region around Moss Landing is responsible for overdraughting the groundwater to support local agriculture, so a desalination plant is also an attractive option in conjunction with the electric power and cement plants. A pilot plant is being built in nearby Santa Cruz to address water shortages during drought years.

As the plant produces only ten tons of cement daily and its product’s structural performance still must be tested, it is too early to say the climate crisis is solved. But the technology has the promise of contributing substantially to dramatic reductions in greenhouse gases attributable to buildings. Seventy percent of the electricity produced in the U.S. goes to buildings, and electric power production is responsible for more than half of all GHG emissions. It would be lovely if Calera’s process turns out to be as economically and environmentally attractive as it appears to be so far.


You can read more about Calera. It is featured in an August 7 on-line article on Scientific American’s web site, the promise of Calera cement is described in more detail.