US-based Sublime Systems has raised US$40m to develop new technology to produce low-carbon cement. According to Bloomberg, Sublime has come up with a process that reduces energy use and carbon emission by splitting the cement-making process into two parts.
The first step is the production of calcium in a form that will chemically react with silicon, the key element in sand. Sublime reduces energy use and carbon emissions in this step by avoiding limestone and using electricity rather than coal-fired heat.
The second step, which is yet to be developed, involves processing the silicon in a reactive form. Silicon in sand is highly stable, so making it reactive is not easy, but early research suggests it can be done, says Sublime. For its first batch of cement, Sublime is using reactive silicon available in nature.
The resulting Sublime cement will then be sold as a mixture of the reactive calcium and reactive silicon. When water and gravel is added, the chemical reaction begins and the mixture starts to harden into concrete. Sublime currently has a small facility producing 100tpa of this low-carbon cement. It plans to use some of the US$40m raised to scale that up to as much as 40,000tpa by 2025.
According to Yet-Ming Chiang, professor at the Massachusetts Institute of Technology, who is behind the new invention, although there is a long way to do to prove the technology can work at scale, Sublime is aiming to a commercial-scale plant by 2028.
Thailand's Siam Cement Group is a strategic investor in Sublime Systems.
