A Silicon Valley start-up says that it has found a way to capture the carbon dioxide emissions from coal and gas power plants and absorb them in cement.
Cement production is one of the largest sources of carbon emissions in the United States; coal-fired electricity plants are the biggest source.
“With this technology, coal can be cleaner than solar and wind, because they can only be carbon-neutral,” said Vinod Khosla, a Silicon Valley billionaire. His venture capital firm, Khosla Ventures, has invested about $50 million in Calera. On Monday, Calera will announce that Peabody Energy, the world’s largest coal company, has invested $15 million.
Calera says that by changing carbon into a building material, it can make carbon reduction economically attractive, especially in places where there are no government subsidies or carbon taxes.
In 2007, Brent Constantz and Mr. Khosla formulated plans for Calera. Though the company declines to share precise details of its process, it says that it combines carbon dioxide with seawater or groundwater brine, which contains calcium, oxygen and magnesium. It gets left with calcium carbonate and magnesium carbonate, used for making cement and aggregate.
To make its cement more usable for manufacturers of traditional Portland cement, it is also making concrete blends of 20% Calera cement and 80% Portland cement – the calcium silicate binder used in concrete for buildings, bridges and highways.