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Practical Magic

A defense of geoengineering

Fantasy or nightmare? If you look beyond extreme ideas such as space shades, there's much to like about this fast-evolving category of climate tech.


Klaus Lackner, director of Arizona State University's Center for Negative Carbon Emissions, developed the "mechanical tree" technology being commercialized by Silicon Kingdom.

How far should humans go to save Planet Earth?

That was my first question in early March, when a new book about geoengineering, "Hacking Planet Earth," authored by journalist Thomas Kostigen, landed on my desk. As a self-avowed technophile, I’m more than willing — some might say too willing — to embrace the idea that technological ingenuity might be able to give Mother Nature an assist as humankind grapples with the physical risks of global warming. For that reason, we need to reboot how we discuss geoengineering — a concept once described as "nasty but necessary."

In its purest sense, geoengineering refers to the deliberate manipulation of the environment to help thwart the effects of global warming.

Historically, the proposed examples have been pretty far out — including some in the literal sense, such as the mirrored "space shade" originally proposed back in 1989 that would deflect the sun’s rays. (Like the white, cool roof concept used for buildings only on steroids and in orbit.) Intriguing? Yes, but not immediately feasible.

Another pretty radical solar geoengineering idea, explored in the book, involves spraying the stratosphere with the same mission in mind: deflecting the sun. A plan to do just that, the Stratospheric Controlled Pertubation Experiment (which goes by the much more accessible acronym SCoPEx), is being spearheaded by Harvard University professor David Keith. The potential upside: The planet’s temperature could be cooled. The downside: The substances that would be sprayed into the atmosphere are composed mainly from sulfur, so essentially we’d be injecting pollutants at sky-high levels to control climate change. Not exactly an easy idea to sell.

Other controversial concepts you’ve doubtlessly heard about that are both a bit more real: work being done to stabilize the power ice caps by organizations such as Ice911 or a marine cloud brightening idea for cooling the oceans, which could help save the world’s dying coral reefs.

For some, ideas of this nature are equal parts fantasy and nightmare. It’s easy to see why the working title for Kostigen’s book was "Frankenplanet." But you also could argue that any climate tech solution that focuses on drawing down the overabundance of carbon dioxide causing global warming is part of the geoengineering movement.

Take the "mechanical trees" being developed by Arizona State University and Silicon Kingdom Holdings. The technology relies on wind to blow air through the system, capturing carbon dioxide with stacks of sorbent-filled disks that look like really high-pile shag carpeting (think of them as the leaves). Once absorbed and sequestered, the gas can be used for synthetic fuel or for applications in the food and beverage industry.

Mechanical trees, carbon capture

Each "tree" contains 12 columns of these devices, which can remove 1 metric ton of CO2 daily — a full-scale farm potentially could remove 3.8 million metric tons annually at a price of less than $100 per metric ton, according to Silicon Kingdom, which announced its intention to commercialize the technology in April 2019. An article about the technology in the March edition of Fortune (subscription required) suggested the trees could cost from $30,000 to $100,000 each.    

In late January, the National Oceanic and Atmospheric Administration received $4 million from Congress to study the SCoPex and marine cloud brightening approaches. But private-sector funding has been slower to materialize, according to Kostigen.

"What’s standing in the way has been a great degree of lethargy and people not taking it as seriously and as critically and as responsibly as possible, and I think that’s changing now," he told me in late March. (You can listen to my entire conversation with Kostigen on the GreenBiz 350 podcast.)

Obviously, that’s changing, especially for companies focused on developing carbon capture and removal technologies — research by the Carbon XPrize estimates that more than $2 billion has been poured into startups and not-so-startups in the sector, with high-profile entrepreneurs such as Microsoft co-founder Bill Gates leading the charge. The feds also seem interested: The Department of Energy in late March opened up $22 million more for research on direct air capture solutions. 

Many decry carbon capture technology as an easy out for the fossil fuels industry, one that gives them some cover for ongoing oil and gas extraction activities. That’s a legitimate concern, especially if it’s the only approach that continues to receive federal funding moving forward.  

But the fact remains: We’ll never reach the goals of the Paris Agreement without embracing solutions that undo at least some of the damage of industrial emissions. We need to think radically, and it would be foolish to overlook technologies and approaches that could help Mother Nature do her job.

This article first appeared in GreenBiz's weekly newsletter, VERGE Weekly, running Wednesdays. Subscribe here. Follow me on Twitter:@greentechlady.

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