Microsoft's ambitious efforts to eliminate its carbon footprint involve lowering emissions and removing carbon from the atmosphere. The emerging carbon capture industry is attempting numerous methods, one of which involves rocks that naturally absorb the substance, but that carbon still has to go somewhere.
Microsoft has struck a deal with Heirloom Carbon, a startup that has developed a process for using limestone to capture carbon to fight climate change. The technique could contribute to Microsoft's ongoing attempt to become carbon-negative.
Limestone naturally absorbs carbon over many years, but Heirloom's method accelerates the process. The company uses a kiln powered by renewable energy to heat crushed limestone to around 1,650 degrees Fahrenheit, which separates it into carbon dioxide and calcium oxide. Adding water to the calcium oxide allows it to absorb sufficient amounts of carbon within days, after which Heirloom re-inserts it into the kiln to restart the cycle.
A little late posting this one...
From the article: