Fixing cement’s carbon problem

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On the Catalyst with Shayle Kann podcast this week:

Concrete is an incredible material. It’s essentially pourable rock, and we use it in almost every part of the built world. We also use more of it than any other manufactured material in the world — about 3 tons per person annually.

And the secret ingredient in all this concrete? Cement. Think of it as the glue that binds the crushed rocks in concrete together. 

But here’s the problem. Making cement emits lots of carbon. The cement industry alone produces 8% of global CO₂ emissions.

Why? First, the process happens at 1,500 degrees Celsius, a temperature so hot that companies often burn coal to reach it. Second, the chemical reaction used to produce cement releases carbon dioxide. 

So what are the solutions? 

In this episode, Shayle talks to Leah Ellis, co-founder and CEO of Sublime Systems, a startup that has developed a novel way to produce cement at room temperature without releasing carbon dioxide. Shayle’s venture capital firm Energy Impact Partners is an investor in Sublime.

Shayle and Leah discuss:

• The key properties of cement and why we use so much of it.
• The chemistry of cement and why it releases carbon dioxide.
• Alternative chemistries to Portland cement, the most common and useful formulation.
• Ingredients you can add to the mix, known as ​“supplementary cementitious materials,” to offset some of the Portland cement required (such as fly ash from coal-fired power plants).
• Adopting performance-based standards that allow more flexibility in the materials used in cement.
• Replacing coal with electrification and alternative fuels in cement kilns.
• Post-combustion carbon capture for cement kilns.
• CarbonCure’s technique for injecting carbon dioxide into concrete to increase strength and reduce the amount of cement required.
• Sublime Systems’ electrochemical technique for manufacturing cement without carbon emissions.

Recommended resources:

• The New York Times: Making the concrete and steel we need doesn’t have to bake the planet
• Canary Media: Major construction firms team up to get the carbon out of concrete
• Bloomberg: Breakthroughs are helping even cement and steel go electric
• E&E News: Congress wagered on ​‘low-carbon’ concrete. Will it pay off?
• Canary Media: Cement is terrible for the climate. California just passed a law to fix that

Catalyst is a co-production of Post Script Media and Canary Media.

Catalyst is supported by Scale Microgrid Solutions, your comprehensive source for all distributed energy financing. Distributed generation can be complex. Scale makes financing it easy. Visit scalecapitalsolutions.com to learn more.

Catalyst is supported by CohnReznick Capital, a trusted source for renewable energy investment banking servicing the U.S. sustainability sector. Visit cohnreznickcapital.com to learn more.