Waste processing by the cement industry is taking a further step in combating CO2 emissions into the atmosphere. In the United States, where there are 2,775 gas and coal-fired thermoelectric plants, a California experience can help to significantly reduce the release of carbon dioxide - considered the main cause of the greenhouse effect.
Calera - a California company that researches carbon reuse technologies - ensures that it is able to remove up to 90% of the CO2 from the smoke emitted by the Moss Landing plant, transforming it into carbonic acid and then into calcium carbonate (CaCO3). The mineral is a raw material for the production of Portland cement. In addition to Calera, Carbon Sciences, also based in California, does similar research.
The pioneer is biomineralization specialist Brent Constantz of Stanford University. "All we need is water and pollution," he says. The process consists of transforming CO2 into carbonic acid H2CO3, using the heat of the smoke itself to generate water (H2O). "From the mixture of water and the polluting gas, a carbonate sludge (CO3) is produced which is then converted into calcium carbonate," says Constantz.
What inspired the research were corals and oysters, which produce reefs and shells from calcium carbonate, removing CO2 from the sea and helping to balance the pH of the oceans. Brent Constantz calls this "biomimetic", that is, mimicking chemical processes that occur in nature. The researcher recalls that the carbonate sludge is mixed with calcium-rich seawater to extract calcium carbonate.
Alliance with the environment
Brent Constantz ensures that his invention will bring significant environmental gain to the cement industry. "Instead of mining limestone to extract calcite in order to produce Portland cement, this process can be replaced by the removal of calcium carbonate from pollution," he says. "We are talking about the reuse of carbon in a productive and economically sustainable way," he adds.
Also according to the researcher, his invention can completely change the environment built in the cities. "Today, architects think: how can I minimize the amount of concrete I'm using in my project? Their concern is to reduce the carbon footprint as much as possible. Instead, we can see the built environment as a place to sequester carbon dioxide. Concrete can become an ally of the environment, "he says.
For Brent Constantz, one of the biggest beneficiaries of his invention may be concrete pavement. "Instead of the asphalt, which is a large emitter of CO2, the concrete that uses the calcium carbonate extracted from the plants retains carbon dioxide. In addition, the cost of concrete production also tends to reduce, "he says. Calera's research began in 2008. Carbon Science, which also started its studies in 2008, started another line of research. The goal is to extract hydrocarbons from CO2 to turn them into fuel.
Find out more about Brent Constantz's research:
https://youtu.be/LhST0dKMwY8
Credit: Cement Itambé