Producing cost-effective, zero-carbon cement using renewable electricity.
Humanity produces a staggering four billion tons of cement every year — it is the foundation upon which the modern world is built. And its environmental toll is equally as astonishing. For every kilogram of cement produced, one kilogram of CO2 is released into the atmosphere. All of that CO2 accounts for eight percent of global emissions, or, to put that number into perspective, one gigaton more than the entire country of India. If we are to ever meaningfully combat climate change, we must decarbonize this industry.
Cement production creates CO2 emissions in two major ways: generating the heat used to convert its raw materials, namely limestone, into clinker, the direct precursor to cement itself; and the chemical reaction that occurs when limestone is sintered, splitting the rock into lime and carbon dioxide gas.
Sublime Systems, founded by electrochemist Leah Ellis and serial entrepreneur Yet-Ming Chiang, is the first company with a potential pathway to decarbonizing both parts of the cement process, thereby producing cost-effective, zero-carbon cement. They call their product, aptly, electrochemical cement.
Sublime is applying proven industrial electrochemical concepts to create a platform that can scale to meet the world’s demand for the building material. Aluminum, hydrogen, chlorine, magnesium, copper — all these commodities are produced using large-scale electrolytic processes. The techniques work. The company currently runs its process at a rate of kilograms per hour, and is working on scaling to tons per hour.
Sublime's platform converts limestone to lime at room temperature, making the CO2 produced during the conversion process easier to capture, and reducing overall energy consumption. In fact, Sublime's process can be completely powered by renewable electricity, in which case its operation is completely carbon-neutral.
Ellis, an electrochemist by training, spent the early part of her career working on lithium-ion batteries, optimizing them for EV use. Chiang’s reputation precedes him in the battery and materials science worlds, having founded multiple companies including Desktop Metal, A123 Systems, Form Energy, and others. Ellis knew, if she had the chance, Chiang would be the person to work with on her next venture. When she received the prestigious Banting Postdoctoral Fellowship from the Canadian Government and an introduction to Chiang from Jeff Dahn, a lithium-ion battery pioneer, it was time to move to Cambridge, MA, and get to work.
“I chose to solve cement’s decarbonization challenge because of the impact any advance to conventional processes would make,” Ellis notes. “The cement industry and its emissions are equally massive — a 1% improvement in efficiency in this sector will have a greater environmental impact than a 1% boost in battery efficiency. A small improvement in a big problem creates a big impact.”
Ellis and Chiang quickly realized that their platform would not just lead to small improvements in the efficiency of cement production, but rather a wholesale elimination of all emissions from the cement-making process.
The pair remain realists, however, they know that changing an industry as mature and embedded as cement manufacturing, takes time. “The challenge is humbling,” Ellis is quick to point out. “But the opportunity is enormous.” As Sublime’s process matures, its superior product, zero emissions, and low production costs will make such change easy.