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This Is CDR Episode 23: Combining DAC and Enhanced Rock Weathering with Heirloom

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 have an exciting...

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 have an exciting presentation from Max Scholten and Noah McQueen of Heirloom, a CDR startup that brings an attractive simplicity to the field.

Among the many CDR startups we’ve covered, two approaches tend to predominate: direct air capture (or DAC), which uses chemical solvents to filter carbon dioxide out of the air, and enhanced rock weathering, which seeds fields and coastlines with carbon-dioxide-absorbing rock dust that gradually precipitates into the ocean.

The innovation of Heirloom is to combine these two ideas. In their cyclical process, carbonate rocks are fed into a 900 degree reactor, which breaks them down into CO2 and calcium oxide. The CO2 is captured and stored underground; the calcium oxide dust, highly reactive to air, is laid out in engineered structures (picture cookie trays on shelves in an industrial kitchen and you’ll be closer than you think, since Heirloom used cookie trays in their prototypes) where it can absorb more carbon dioxide from the air, reforming into carbonate, to be fed back into the reactor. This reformation process takes months or years in nature, but Heirloom has accelerated it to under two weeks. You can picture the entire cycle as something like wringing out a sponge (the carbonate rock), then reusing it to soak up more mess (the CO2).

Heirloom’s goal is to remove 1 billion tons of CO2 from the atmosphere by 2035. As Max notes, this is extremely ambitious. But there are reasons to believe it’s possible. While the process is innovative in its totality, each individual component is pretty low-tech. An Heirloom unit can be built with off-the-shelf solutions from the agriculture, mining, and warehouse automation industries. At its most basic level, it’s just putting dust on trays – there’s nothing particularly expensive or advanced there.

Thus, the concept is modular and scalable, with the main restraints being availability of carbonates (they’re very common, but you don’t want to burn energy shipping them to a site or you defeat the entire purpose) and proper terrain for underground carbon sequestration. That leaves a lot of options, and it’s easy to imagine (as Max suggests) seeing fields of Heirloom units along the sides of highways the same way we now see solar and wind farms. Getting back to the 2035 goal, as ambitious as it is, Heirloom units could remove a billion tons of CO2 a year using less land area than Disney World. All it will take is the political will to create a true carbon removal market.

There’s enormous promise in Heirloom’s approach, and their presentation is super-exciting. Please check it out above, and be sure to check back next week for more This Is CDR. For more, you can watch 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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