The Department of Energy recently awarded $39 million in grant funding to 18 universities and labs across the United States that are working to cut down the carbon footprint of various construction materials. The labs are trying to create replacements for things like concrete, wood, insulation, and paneling.
Cement production, the base material used to create concrete when mixed with other materials like water, sand, and other cohesives, accounts for 7% of global carbon emissions, in large part due to the burning of quarried limestone.
It is created when limestone is burned at extremely hot temperatures. That combustion process creates a large amount of CO2 that is then released into the atmosphere.
Wil Srubar, an associate professor of civil and architectural engineering at the University of Colorado Boulder, received one of the highest grant amounts, $3.2 million, for his work to create a greener alternative to quarried limestone.
“We’re trying to make a cement that stores and sequesters more CO2 than is emitted during its manufacture,” he said.
Srubar hypothesized that microalgae could create limestone in a way that was healthier for the Earth’s atmosphere.
Through a $500,000 grant a year ago, he tested his theory on a microalgae known as coccolithophores, which, through photosynthesis, sequesters carbon out of the atmosphere. The algae creates an “armor,” as Srubar describes it, that greatly resembles the same compounds as limestone. Through a process that separates the “armor” from the algae itself, Srubar was able to isolate the greener limestone alternative and burn that instead.
Srubar says it is a carbon-neutral process that takes the same amount of CO2 out of the atmosphere as it adds in during the combustion process to create cement.
“It’s really plug-and-play with conventional cement and concrete manufacturing,” said Srubar. “The only thing that has to change is switching from quarrying limestone to growing it. Every other part of the process is identical.”