To form their skeletons, corals undergo a cascade of fleeting chemical reactions. Unstable carbonate chemicals react to form new, more stable carbonates, each of which exists for only a few milliseconds. Scientists at Fortera wanted to find a way to hit “pause” on this natural process so that they could isolate an intermediary that resembled cement. Then, if that “paused” substance is later mixed with water, sand, and other aggregates, it would be like hitting “play”— it would become cement. Between 2007 and 2009, scientists at Calera tried thousands of times to produce one of those intermediaries. “It failed miserably for 18 months,” Farsad said.
Eventually, they found their intermediary: a chemical called vaterite, produced by mixing calcium carbonate from limestone with a solution made from captured carbon dioxide.
The concept was initially controversial, with many scientists expressing skepticism that the idea would work. While Calera did develop a product, the idea didn’t take. In 2015, the company shelved its patents, and Constantz stepped down from his position as CEO. The concept was largely forgotten until 2019, as public concern about climate change mounted. “People started calling and saying, ‘Hey, that original technology, is it worth revisiting?’” said Gilliam, who at that point had taken the helm of the company under its new name, Fortera.
But although the underlying technology, inspired by coral, is the same, Fortera has a different business model than its predecessor.
Calera saw itself as a carbon capture and sequestration company. Its first partners and investors were coal plants. Fortera, in contrast, is working with manufacturers of traditional cement, also called Portland cement. Brand-new Fortera plants, called ReCarb plants, are bolted onto already existing Portland cement plants. Fortera’s technology then takes the carbon dioxide emitted by the existing plant and incorporates that gas into its product, ReAct Cement. This cement can then be used on its own or mixed with Portland cement to form a hybrid product.
One element of Fortera’s process that’s particularly attractive to manufacturers of Portland cement: It eliminates a lot of waste.
To make Portland cement, you heat limestone in a kiln. The limestone then undergoes a chemical transformation in which nearly half of it is lost as carbon dioxide. “By actually capturing that, we effectively double the amount of product,” Gilliam said. That allows cement manufacturers to lower production costs while eliminating the “green premium” that can make it more difficult to sell sustainable products.
It’s a win-win situation: Fortera’s production method allows cement companies to double production, raise profits, and cut down on emissions.
“We figured out how to take that technology that we’d already proven out but do it in a way that actually works with the cement industry,” Gilliam said.
Transforming an Industry
ReAct isn’t a zero-carbon product — yet. The ReCarb facility and Portland cement plant form a closed-loop system. By sequestering the CO2 produced when limestone is heated to form Portland cement, the process cuts down carbon emissions by 70 percent. However, it doesn’t eliminate emissions from using fossil fuels to run both the plants.
Fortera isn’t the only company that aims to transform cement.
Some Portland cement manufacturers are taking it upon themselves to lower emissions by decarbonizing the energy supplies used to heat their kilns or employing carbon capture. Meanwhile, startups like Brimstone and Sublime Systems have developed their own chemical processes that eliminate or lower carbon dioxide emissions. Both companies received industrial demonstrations grants from the U.S. Department of Energy earlier this year.
“There are a variety of solutions that need to be deployed to reach our net-zero targets by 2050,” said Skinner. “We’re going to see a lot of variety based on market preferences, regional availability of materials, what the existing infrastructure looks like.”
Skinner believes that Fortera is playing an important role in this pivot, because of the competitive price of its product and the fact that it can be mixed with traditional cement. “This is a great near-term solution,” he said.
