We are closing in on zero-carbon cement

12/27/23 • 68 min

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The cement industry, responsible for roughly 8 percent of total global carbon emissions, is notoriously difficult to decarbonize. But a new startup, Sublime Systems, aims to manufacture zero-carbon cement that can easily be substituted for the traditional version. In this episode, Sublime CEO Leah Ellis talks through the company’s vision and process.

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David Roberts:

Of all the so-called “difficult to decarbonize” sectors, cement is among the most vexing. Making cement produces CO2 not merely through fuel combustion (in kilns that reach temperatures of up to 1400 C), but also through chemical processes that split CO2 off from other molecules. It is responsible for roughly 8 percent of total global carbon emissions.

Most gestures at decarbonizing cement to date are fairly desultory — things like adding special additives or injecting a little CO2 when the cement is mixed into concrete. The only widely available method that could theoretically produce no- or low-carbon cement is post-combustion carbon capture and sequestration. And there are plenty of people who would question whether that's actually viable at all, much less widely available, given that it would roughly double operational costs for a cement plant.

There are lots of startups out there attempting to solve this problem (as reported by Canary last month). Perhaps the most intriguing is Sublime Systems, a team that has developed something truly new and exciting: a system for manufacturing cement that requires no high heat (thus no combustion emissions) and uses inputs that contain no carbon (thus no chemical emissions). That makes the cement, at least potentially, not just low-carbon but zero-carbon. What’s more, the company says that, in form and performance, its product is a perfect drop-in substitute for traditional Portland cement, so it wouldn't even require any changes in the construction industry.

A carbon-free drop-in cement substitute — at scale and at competitive cost — would be genuinely transformative. I contacted Sublime CEO Leah Ellis to talk about cement chemistry, the company’s process, and the plan for reaching megaton scale. This one was truly fascinating and educational for me; I think you will really like it.

All right then. Leah Ellis, CEO of Sublime Systems, welcome to Volts. Thank you so much for coming.

Leah Ellis

Thank you so much for having me.

David Roberts

I'm excited today to talk about concrete, everybody's favorite subject. But first I wanted to ask you, I know you and your partner originally were trained as and educated as battery scientists. I'm just curious how you ended up here. What drew you into this area, this problem?

Leah Ellis

Yeah, my co-founder is a professor at MIT, Yet-Ming Chiang, and he's in the material science department, and I'm a chemist by training. I like to think of chemistry as the central science that combines everything from physics to biology. All of the good stuff you can sort of spread into anything from a foundation in chemistry. So I did my PhD in lithium-ion batteries. I worked with a prolific inventor, Jeff Dahn, and after that I wanted to continue working with an inventor. As you may know, in academia, there are so many different styles of research.

I mean, some people like microscopy and mechanisms, but I really like the creative aspect, like discovering something that could be useful or to solve problems. And not many academics and professors think through that lens. So I've always been very lucky to work with prolific inventors, both in my master's and my PhD. So for my postdoc, I sought to work with people who thought like that. So my co-founder, Yet-Ming Chiang at MIT, is a prolific inventor and also a serial entrepreneur. So Sublime is his 7th startup, and five of the previous six have been very successful.

So I didn't join him with the aspiration of becoming a founder. I really knew nothing about entrepreneurship or anything like that, but I did want to invent, and I did love the way he approaches his work from a problem-solving standpoint. So that's what brought us together.

David Roberts

An...

(PDF transcript)

(Active transcript)

Text transcript:

David Roberts:

All right then. Leah Ellis, CEO of Sublime Systems, welcome to Volts. Thank you so much for coming.

Leah Ellis

Thank you so much for having me.

David Roberts

Leah Ellis

David Roberts

An...

Previous Episode

Getting better at mining the minerals needed for clean energy

To create a clean-energy economy, the US badly needs an advanced mining industry that can provide huge amounts of key minerals for batteries and other technologies — and it’s nowhere close to where it needs to be. In this episode, KoBold Metals CEO Kurt House describes the current state of mineral exploration, the significant changes it needs to make, and how machine learning and artificial intelligence can help it get there.

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David Roberts

Building the machines and batteries needed to decarbonize the economy will require enormous amounts of a few key minerals. The proven reserves of those minerals, sitting in mines now operating, are nowhere close to enough to satisfy what is expected to be skyrocketing demand.

Without the minerals, we can’t make the clean-energy economy. And we don't know where the minerals are going to come from.

What's worse, exploring for new mineral deposits has been getting less and less efficient over the last several decades, as the amount of investment needed per successful discovery has risen. We seem to be getting worse at finding this stuff right when we badly need to be getting better.

That state of affairs has drawn in several new startups that endeavor to use machine learning and artificial intelligence to improve mining’s hit rate. The most talked-about is KoBold Metals. With financial backing from Bill Gates, Jeff Bezos, and other big-name investors, KoBold is now exploring for minerals on four continents.

To get a better handle on mining and how we can improve at it, I contacted KoBold CEO Kurt House. We talked about the projected gap between supply and demand, the somewhat primitive way current exploration works, the massive data-gathering and coordination project the company has undertaken, and the role of justice and equity in this AI-accelerated future of mining.

Kurt House, CEO of KoBold Metals, welcome to Volts. Thank you so much for coming.

Kurt House

I'm so pleased to be here. I'm a huge fan. I listen to the podcast all the time, so it's fun to talk to you live.

David Roberts

We're going to talk about something that is of great interest these days, which is finding the stuff that we need to build the clean energy economy. This is something I did a series of articles on a couple of years ago, and it's come up repeatedly over the years. People talk about possible shortages of materials as one of the bottlenecks that might slow the clean energy transition. So maybe let's just start there with setting some context, talk a little bit about the big four minerals that you focus on and sort of what we know about how much we have access to and how much we project we're going to need.

Kurt House

Perfect setup question. So, the energy transition is fundamentally about getting off fossil fuels. It's fundamentally about electrifying the economy to the greatest extent possible. So we electrify transport, all electric generation becomes renewable, et cetera, et cetera. That requires a lot of very specific materials and very specific materials because different elements have different physical properties, obviously, and they do different things better and worse than others. And some of those elements are really difficult to substitute for, for very, very deep physical reasons. So KoBold is focused on what we call "the materials of the future," and those are lithium, cobalt, copper and nickel.

That's not at all to say that there aren't other important materials for the energy transition.

David Roberts

Are those four the most important? By just mass, just, we need most of those —

Kurt House

No, by total mass, it'd probably be aluminum and steel, iron for steel. The reason these are so important, there's two orthogonal reasons that we focus on these. One is how difficult they are to substitute for in specific applications. And I'll talk about that. And then the orthogonal element to it is that they are exploration problems. So aluminum is really useful in a whole bunch of reasons, but it's not an exploration problem. There's just gobs of bauxit...

Next Episode

Volts podcast: Will Toor on Colorado's burst of clean energy policy

In this episode, Will Toor of the Colorado Energy Office shares about the state’s ambitious climate agenda and the array of energy policies they’ve been passing under a Democratic political trifecta.

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Washington, DC, is a slow-motion nightmare right now, but out in the states — at least the states that Democrats control — climate and clean energy policy is still happening. A few weeks ago, I covered the fantastic policies recently passed in my home state of Washington (see also my podcast with Washington legislator Joe Fitzgibbon).

Today, we turn our gaze to Colorado.

In 2018, Democrats gained a trifecta in the state — the governorship and both houses of the legislature — for the first time since 2013. They promptly got busy passing a vast array of clean energy policies: reform of electric utilities, support for electric vehicles and charging infrastructure, new restrictions on oil and gas production.

During this year’s legislative session, Gov. Jared Polis released a comprehensive roadmap to 90 percent statewide reductions in greenhouse gas emissions by 2050 and the state legislature tackled clean buildings, industry, environmental justice, reform of state transportation agencies, reform of natural gas utilities, and on and on.

To discuss this flurry of activity, I turned to a man who has been involved in Colorado politics since the previous century: Will Toor.

Toor was mayor of Boulder from 1998 to 2004. From 2005 to 2012, he was Boulder County Commissioner. During all that time he was also board chair at the Denver Regional Council of Governments, where he led efforts on climate policy. He then became director of the transportation program at the Southwest Energy Efficiency Project, until 2019, when the newly elected Polis appointed him to run the Colorado Energy Office.

Toor has had a hand in shaping Polis’s energy agenda from the beginning, and he has been closely involved in negotiating bills through the legislature. He helped walk me through Colorado's sector-by-sector approach to emissions, what the state has accomplished so far, and what might be next for it.

Listen, enjoy, and if you appreciate work like this, please consider becoming a paid subscriber to Volts.

As a bonus, here’s a picture of Toor in 2003, as mayor of Boulder, hosting visiting scholar Noam Chomsky.

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David Roberts

All right, with no further ado, Will, welcome to Volts.

Will Toor

Thank you.

David Roberts

So I've been following states and climate policy for a long time, and it seemed like a few years ago, Colorado just kind of burst out of the gate at a full gallop and has been going really strong now for two sessions of the legislature. So maybe just by way of starting, tell us some about the political developments of Colorado over the last five years that put all the pieces in place that allowed this burst of activity.

Will Toor

Yeah, really, I think what happened was that in 2018, we both elected a new governor, Jared Polis got elected governor on a platform of, among other things, 100% renewable electricity by 2040 and bold climate action, and we elected a Democratic Senate. We had had a Democratic House, but had not had a Democratic Senate since 2014. And so the combination of having a governor who was committed to climate action and a House and a Senate that were aligned and the fact that there was just kind of a pent-up demand for action on climate and clean energy really set the stage for a kind of monumental legislative session in 2019.

So that year we had, depending exactly how you count it, something like 15 major bills on setting climate targets, moder...