E18 DAC + Concrete with Chris Neidl & Na'im Merchant

In this installment of This Is CDR we are pleased to welcome OpenAir’s own Na’im Merchant and Chris Neidl to to survey the primary pathways by which concrete can sequester CO2 in concrete, and how direct air carbon capture (DACC) plus concrete represents a scalable CDR solution we can start deploying today.

Hosted by Sue Dorward and Megha Raghavan

Summary Transcript

OpenAir has been focused on the concrete potential for CDR and sequestration for years. In 2021, the Orca plant in Iceland began operation - DAC carbon removal is going mainstream now.
What is needed is DAC that is distributed and modular. These features will enable driving down cost from the current $600/ton to a favorable level like $100/ton. To achieve this, we need innovation in technology, economy of scale, mass production. These create the experience curve which makes costs drop. We are in the decade when we must launch technology to get the experience curve started.
As we launch, we have to deal with the fuel issue in some ways. Will CO2 go to increasing oil well yields? We hope not. But maybe CO2 can produce fuel to displace oil and be used for generating - storing excess solar energy. But we want to look at other ways of using CO2 also - where it can add value in niche markets. Niches are places where innovation can happen that leads to broad market penetrations. The learning rate increases with more facilities in a market. More niches create market resiliency for CO2.
Solar transformed from niche to mainstream over five or six decades. Early niches were NASA uses, illegal growers, solar calculators. Some of these were pretty expensive, but when scale-up was realized, the cost plummeted. Right now the DAC niche market are greenhouses, beverage industry, and some movement in solar storage, indoor air quality improvement, and possibly data center applications. In all these cases, and elsewhere, we want DAC that is distributed and modular - small decentralized units that can be autonomous, that are stackable. Solar has these features. That manipulable aspect is a path to innovation because people can try things. It is something that can be put onsite so it is cheaper.
A high learning rate and innovation rate spring from modular and accessible pieces. Concrete can benefit from this! Concrete is a big market of 3.5 Gt/year - concrete is essential to civilization. The Portland cement - a small portion of the concrete - is the big CO2 source. But concrete also naturally remineralizes CO2. So if we can make that happen faster, and put the CO2 right into the concrete, that is a great benefit.
The adding of CO2 to concrete is a natural synergy. It is readily integrable - not a new market; people already need concrete. DAC units can be located right at concrete plants. But concrete business is tough; competitive. it is hard to sell new ideas. And the availability of CO2 has been uncertain. Putting DAC units in concrete plants gives reliable supply. Making concrete “low carbon” is a selling point.
A typical DAC unit of today could easily fit within a typical block plant (based on the size of equipment at the Icelandic startup). There are other efforts, like CarbonCure - displacing some cement with carbon. Putting CO2 into concrete is a very permanent, verifiable means to sequester. It is a local use - no transport to a disposal site. We can see how concrete can give us the necessary niche: it gives a chance to buy down the DAC cost. It is a very important market for carbon!
To make sure it happens, OpenAir has been promoting policy. The LECCLA, L-NET, and CDRLA efforts have been in this direction. They promote low embodied carbon concrete. They focus on government procurement policy - laws that act to create demand for low carbon product. OpenAir is also focused on activist business - sometimes it just takes one business to show people what can be profitable. We want to encourage numerous small DAC businesses and some that already exist are pursuing relationships with concrete plants. But concrete plants are not yet seeking DAC partners - we need to change that.
Q&A How does CO2 affect concrete? We think the performance of CO2 concrete is good, but sometimes specifications are written with specific ingredients and we need to promote more performance-based specification. For CO2 in other products, there is not much production volume. It can be expensive to lock in the CO2. Fortunately, niche markets are often less cost-sensitive.
Why focus on DAC for the CO2? We want to focus on the added value of removing carbon from the atmosphere, and the local sourcing of the CO2 so it is not transported. These things add value to concrete.
Can biochar go in concrete? That is a good question.
There is waste heat in concrete manufacture - is that a synergy for DAC? Yes, there is a LOT of waste heat in making portland cement, but there is also some waste heat from block kilns and some kinds of prestressed concrete. The portland cement process has ample waste heat to use in DAC desorption stage.
How much CO2 can go in concrete? Another good question
To summarize, procurement laws are critical - they create market for low CO2 concrete. Better specification laws allow low CO2 concrete a market share. Investment tax credits can promote this too. Sometimes simply saying to the market - make the product have low CO2 output is enough, the market will find ways.
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