How Green Is Your Sidewalk?

Everyone knows the generation of electricity is the largest source of greenhouse gases. What fewer people know is that the runner-up is cement. On average, the amount of CO2 emitted by the cement industry is nearly 900 kg of CO2 for every 1000 kg of cement produced. If you consider how much cement is out there, you start to wonder how it isn’t number one. The CO2 emissions have two main sources: 40 percent comes from burning fuel used in the manufacture of cement, and 50 percent comes from the chemical process used to actually create it. The Sentinel reports that Los Gatos-based Calera Corp. is tackling the problem by manufacturing cement from the carbon dioxide sequestered from power plants. Rather than letting that gas into the air, it combines the gas with seawater to form solids that can be used in manufacturing cement. As much as half the mass of Calera’s cement comes from this method, and research—aided by a $20 million federal grant—is moving ahead to figure out how to improve those figures. The big test for Calera, which has been making test batches at its Moss Landing facility for three years, is about to take place, and it’s happening right here in Santa Cruz. A 400-foot walkway along Morrissey Boulevard will be paved using Calera cement. Admittedly, it’s not a lot, but all eyes will be watching to see if the new cement can really replace the old standard Portland cement. If so, it will likely be used for other local and eventually statewide projects. Read more at the Santa Cruz Sentinel.

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