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In Holyoke, Mass., on the Connecticut River, they’re replacing a closed paper mill with a factory that will make “clean cement.” If it lives up to hopes, that would be a big deal since making cement is a huge emitter of carbon. From the article in Heatmap (read it here):

More than half of the emissions from cement come from a chemical reaction that’s intrinsic to its production. Cement consists of lime, silica, and water. It’s made by first heating up limestone in a kiln to more than 1,400 degrees Celsius (2,550 degrees Fahrenheit) — a level of heat that can typically be achieved only by burning coal or natural gas — to produce reactive lime. The bigger problem, though, is that limestone contains carbon, and as it heats up, that carbon is released as a gas. So even if you could heat the kiln with clean electricity instead of coal, there would still be carbon emitted by the process.

But Sublime has found another way. Ellis and her cofounder Yet-Ming Chiang — a serial entrepreneur who is also behind the buzzy battery startup Form Energy — developed a new way to make reactive lime that does not require limestone. Instead of heating up rocks in a kiln, they drive the chemical process with electric currents. This enables the company to avoid limestone and use a variety of other raw materials that do not contain carbon to produce lime.

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