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This Is CDR Episode 27: Modular DAC with Sustaera

This Is CDR is an ongoing series of online events to explore the range of carbon dioxide removal solutions that are currently in development. This week, we hear from Shantanu...

This Is CDR is an ongoing series of online events to explore the range of carbon dioxide removal solutions that are currently in development. This week, we hear from Shantanu Agarwal, CEO of direct air capture startup Sustaera.

Sustaera represents a serious effort at large-scale DAC, focusing on scaling up as quickly and efficiently as possible. While current DAC (such as that offered by Climeworks) costs around $600 per ton of CO2 removed, Sustaera aims to lower the price to around $78 per ton.

As Shantanu points out, many other companies are working on DAC. What distinguishes Sustaera, he argues, is their sorbent. Any DAC process relies on a sorbent that absorbs CO2 from air like a sponge. This can be a liquid or a solid; in the case of one previous This Is CDR presenter, Heirloom, it’s sheets of pulverized rock. Where most other chemical CO2 sorbents are ammonia-based, Sustaera’s sorbent is a solid alkali metal, already available at industrial scale. Cost of sorbent is a major part of DAC pricing, so choosing a widely available material could allow Sustaera them to reduce the cost substantially.

Sustaera’s plan is build out their facilities as standarized, factory-build modular units, each capturing one ton of CO2 per year to start. Each unit uses active air contact (fans blowing air across the sorbent), powered by renewable electricity. Some of the challenges of renewable energy – namely, intermittent power generation as the sun sets on solar panels and the wind slows over turbines – are mitigated by Sustaera’s design. If the electricity stops, the DAC process stops. When the electricity starts again, so does the DAC.

These units could be built in large fields or desert areas, colocated with their own power sources and infrastructure to sequester the captured carbon. 100 acres of Sustaera units could remove a full megaton of CO2. And most impressively, they’re aiming to reach this scale by 2027. The distance we have to go to scale CDR to where it needs to be is daunting, but if Sustaera can actually be capturing a megaton of CO2 per year five years from now, we’ll be off to a very strong start.

The biggest impediment right now, as Shantanu notes, is the currently totally unregulated market for carbon credits. If meaningless carbon credits (for dubiously permanent trees or even more dubious “protection” of existing trees) can sell for $15 per ton, corporate buyers have little incentive to buy real, measurable carbon removal at $78 per ton, let alone $600 per ton. Last week’s This Is CDR speaker, Danny Cullenward, painted a sobering picture of the current carbon market. So we’ll emphasize again that without real, verifiable standards of permanence and additionality imposed by government, neither Sustaera nor any other CDR company will be able to grow.

This is something we can all work on together, and something OpenAir is working on right now with our CDRLA initiative. Please join us, and be sure to check back next week for more This Is CDR. You can also catch up on the whole This Is CDR series on our resources page.

Peter Malamud Smith Peter Malamud Smith is a writer and editor based in Brooklyn.

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