Humanity’s Most Abundant Material Is a Huge Climate Problem

Jesse is on vacation until August, so this is a special, Rob-only summer episode of Shift Key.

The world uses about 30 billion tons of concrete every year — more than any other material except water. It is the most ubiquitous human-made substance in the global economy. It’s also a huge climate problem. Producing cement, which is the key ingredient in concrete, generates roughly 8% of global annual greenhouse gas emissions.

Cody Finke has a plan to change that. He is the chief executive officer and cofounder of Brimstone, a startup that says it can cheaply produce ordinary Portland cement — the kind used in construction worldwide — without carbon emissions. This week, Rob chats with Finke about why cement’s carbon emissions aren’t from fossil fuels, why there are fewer cement plants than you might think, and the all-important difference between cement and concrete.

This episode of Shift Key is hosted by Robinson Meyer, the founding executive editor of Heatmap.

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Here is an excerpt from our conversation:

Robinson Meyer: Concrete is such an archetypal big machine problem in decarbonization. Because not only is it carbon intensive, but also — like car engines or like plane engines but, notably, unlike power plants — maybe like power plants — the technology to do it is extremely dispersed. There are hundreds of thousands of concrete plants around the world, and they all have to be replaced to decarbonize this process. It’s just a huge, huge scaling endeavor, and one that, forces you to reckon with the material implications of decarbonization in a way that, I think, it can often be easier to skip over or, just think, in the form of electricity: Oh, we can just drop new power plants in, we can build renewables. But that’s not how decarbonizing concrete will work.

Cody Finke: I would actually want to challenge that slightly.

Meyer: Perfect.

Finke: So, for many solutions, that’s the case because you’re absolutely right, there are hundreds of thousands of concrete plants. But there are not hundreds of thousands of cement plants. Cement is the binder in concrete, and for the listeners —

Meyer: Yeah, let’s actually do this because clearly I also don’t fully understand.

Finke: Concrete’s the building material. It is the most consumed material on the planet. We make 40 to 50 billion tons of it every year as humans. Concrete is sand, gravel, water, and cement — cement is the glue. Without cement, concrete would just be a pile of sand and gravel — a wet pile of sand and gravel. Cement is essential for turning that pile of sand and gravel into a pourable rock.

But cement is only about 10% of concrete — 10% to 20% — and it's made in large, centralized facilities that are located basically around big population centers. There are only 2,000 or 3,000 cement plants in the world. So it depends on your solution, right? If your solution is making a novel material, then it may require working at the concrete level, which can be good and bad. There’s a lot of those facilities, but they’re also a bit cheaper. There’s good and bad attributes of that.

But if you were to do something like what Brimstone is doing, which is making ordinary Portland cement, then what you have to do is replace those 2,000 or 3,000 cement plants, which is still a big number —

Meyer: It is still a big number, but actually not a very big number.

This episode of Shift Key is sponsored by …

Watershed’s climate data engine helps companies measure and reduce their emissions, turning the data they already have into an audit-ready carbon footprint backed by the latest climate science. Get the sustainability data you need in weeks, not months. Learn more at watershed.com.

As a global leader in PV and ESS solutions, Sungrow invests heavily in research and development, constantly pushing the boundaries of solar and battery inverter technology. Discover why Sungrow is the essential component of the clean energy transition by visiting sungrowpower.com.

Music for Shift Key is by Adam Kromelow.