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Excerpt: The Original Sky Scrubber from Scrubbing the Sky

The following abridged excerpt is taken from the second chapter of Scrubbing the Sky: Inside the Race to Cool the Planet – an in-depth look at the people and the science behind our attempts to pull carbon dioxide out of the atmosphere with direct air capture

The Original Sky Scrubber

by Paul McKendrick

On a warm summer evening in 1992, Klaus Lackner and a friend were reminiscing over a beer on the back deck of Lackner’s home in Los Alamos, New Mexico, about sharing a rare and sought-after computer in a campus research lab in the early 1980s. As the evening wore on, the pair turned their conversation to some of the big ideas people contemplated more frequently in the past, when the potential for unintended impacts was less of a concern. A few beers later, the conversation evolved into their own big idea: What if some of the world’s biggest problems could be solved with large colonies of self-replicating machines?

Looking out over the barren, mesa landscape unfolding before them, they envisioned the machines digging up raw dirt, transporting it on ceramic tracks, producing metals from electrified ovens, manufacturing machine parts and solar panels, and building more of themselves, all around the clock in a self-contained system. This particular location that they gazed upon, near former atomic bomb testing grounds, would potentially be large enough to power all of the United States, while other colonies could provide additional services, like cleaning up the excess carbon dioxide building up in the atmosphere. An extremely large processing system would be required to remove carbon dioxide at a sufficient scale to stop global warming, a task that could be carried out by a colony dedicated to transforming the planet-warming gas into mountains of rock.

When the two friends met up for breakfast the next morning, they decided that the previous night’s discussion was not actually all that crazy. They returned to their regular jobs and, in their spare time, began testing the theory for obvious bottlenecks. The most likely in their estimation was the reliance on raw dirt as the main input for the manufacturing to be carried out by the machines. The pair concluded that despite many of the essential elements, like aluminum and iron, being less readily available than in conventional source materials, the machines would just have to work harder to separate the dirt into its elemental constituents. Meanwhile, manufacturing inputs requiring rarer elements, such as copper and platinum, would have to be redesigned or eliminated, and other elements unavailable in dirt—hydrogen, carbon, nitrogen—would be captured from air and rainwater. Any excess materials could then be used for non-critical items.

To capture excess carbon dioxide from the air, the machines would be tasked with constructing carbon dioxide extraction units. The required inputs would be minimal: a metal oxide, possibly magnesium or calcium, and air. Assuming enough wind was present to move air through the extraction units, the metal oxide would bond with the carbon dioxide in the air, producing carbonates similar to naturally occurring minerals. Klaus theorized the total output volume of minerals created by the carbon capture would create a layer roughly a meter and a half thick if it were to cover an area the size of New Mexico.

Excerpted from Scrubbing the Sky: Inside the Race to Cool the Planet by Paul McKendrick. Copyright © 2023 by Paul McKendrick. Excerpted with permission from Figure 1 Publishing. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.


March 1, 2023
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