Scrubbing the Sky: Inside the Race to Cool the Planet

by Paul McKendrick

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.

Drawing on interviews with stakeholders at the intersection of climate science, energy technology, and public policy, Paul McKendrick's investigation traces more than 20 years of technological development with direct air capture, from Biosphere 2; to multi-million dollar promises from Richard Branson, Bill Gates, and Elon Musk; to the opening of Orca, the world's largest commercial direct air capture facility, in Iceland in 2021.

The question of what will be necessary for direct air capture to reach a meaningful scale, and how much it will cost, has fueled intense scientific and political debate, and spurred a value chain that spans finance, industry, technology, policy, and academia.

McKendrick's clear and riveting prose presents the full story of this fascinating pursuit for the first time, inviting readers to learn more about this critical climate intervention option.

Genres: Nonfiction, Science

192 pages, Hardcover

Published March 7, 2023

Reviews

[Nicolas Levy · Rating 4 out of 5]

Scrubbing the Sky offers a rapid-fire tour through the world of carbon dioxide removal (CDR) - a suite of technologies and start-up companies that may become one of the largest assets of the 21st century. Paul McKendrick sets the scene with a notable conference in the early 2010s that convened many of the enthusiasts and skeptics of CDR. In retrospect, this seems like a key inflection point; although the consensus at the time seemed to be that CDR was too expensive to be considered a viable strategy to combat climate change, the ensuing decade has seen a wave of academic and financial interest.

From this point, McKendrick travels back in time to trace the evolution of CDR. This includes the memorable Biosphere experiment of the early 1990s, when NASA enclosed human volunteers in essentially a large greenhouse to mimic Mars's atmosphere (it later became an accidental experiment in CDR when scientists noticed a dangerous increase in CO2 concentrations). A key personality during this early phase was Klaus Lackner, an iconoclastic and creative scientist who did not shy away from clear-eyed calculations about how humanity could draw down CO2 concentrations.

This short book zooms through several ensuing technologies and start ups that are attempting to tackle the problem: from Thermostatic's large, ill-fated direct air capture facility in Mississippi, to Carbon Engineering's quest to learn from other industries in driving down the cost curve of the technology, to the Swiss team Climeworks, which has implemented the largest such facility yet. McKendrick also touches on other related strategies, including the oil and gas industry's role in carbon sequestration, a brief discussion of solar radiation management, and even the potential of seaweed kelp to sequester carbon.

Throughout the book, McKendrick is clear-eyed about how technology, economics, and policy intertwine. While not an overly technical book, he offers informative and clear explanations of different technological options for CDR, their merits and drawbacks, and importantly, their potential to scale to capture billions or even trillions of tonnes of CO2 in a cost effective manner. We also get to meet some of the interesting personalities driving this nascent industry - given the complex technical and economic challenges, these are all by definition innovative and creative thinkers.

While clearly meant as an introduction to the field (clocking in at 166 quick pages), my one gripe with this book is that McKendrick seems not to have seriously engaged with the critiques of CDR. The book does briefly acknowledge the issues of CDR costs, siting (where will we store trillions of tonnes, which is what will likely be needed to keep global temperatures within 1.5-2 C of warming?), and moral hazard (will this decrease the willingness to make hard emissions cuts?), but these issues could have been explored in richer detail. For example, the conference McKendrick cites in the introduction was based around a detailed report by the American Physical Society that raises many such concerns - but we don't learn any more about the main findings and methods of the report. A little more detail on this front could have really made this an integral, nuanced book for policymakers and other stakeholders seeking to get caught up to speed on what is likely to become a significant industry in the next two decades. As it is, Scrubbing the Sky is still a thought-provoking and fascinating fly-over of this emerging world.

[Amy · Rating 4 out of 5]

I struggle to find climate-related books these days that don’t actively damage my mental health. This book didn’t hide the facts, but indirectly offered a more hopeful message than most.
Through a series of prizes and projects, we get an overview of direct air capture: a technology to slow climate change by extracting ‘legacy’ CO2 from the air. The technical challenges in scaling up DAC are significant, but the social and economic challenges are in some ways even greater. It was both frustrating and hopeful to learn how much alternative fuels research was done during the 1970’s oil crisis - and once the crisis passed, we went straight back to business as usual. If you’re interested in the field but are not an expert, I’d recommend this one. It gave a good overview of other climate change mitigation strategies, as well.

[Robert Ronca · Rating 5 out of 5]

Paul McKendrick’s new book, Scrubbing the Sky, is extremely well researched and well written. He has made it easy to read for the layman as he has dispensed with mystifying jargon. Instead, he brings the chronicle of the direct air capture story to life as he weaves the names of iconic, world renowned personages and entities into his timeline. He highlights the evolution of their ideas, what motivated them and the levels of support they garnered from the scientific, business, and political communities. Scrubbing the Sky is an excellent read on the timely topic of direct air capture, which presents us with the difficult choices we must make if we are to stop greenhouse gas emissions and reverse the levels of CO2 in our atmosphere to save our planet. McKendrick’s synthesis of the direct air capture story, from its origins to the present, in a thought provoking, incisive and concise style, makes for an informative and enjoyable read.
Robert Ronca
Calgary, AB
February 21, 2023

[STEPHEN PLETKO!! · Rating 3 out of 5]

XXXXX

IT'S TIME TO TREAT THE SEWAGE IN THE SKY

XXXXX

"This book tells the story of a group of scientists, philanthropists, investors, and advocates who have resisted strong headwinds to provide us with what may become an invaluable intervention option [to climate change]."

The above quote (in italics) comes from this book by Paul McKendrick. He is a best-selling author. Prior to writing books, he worked in the energy sector.

This book examines a relatively new technology called Direct Air Capture (DAC). DAC removes carbon dioxide (CO2) directly from the air. This is not to be confused with carbon capture which captures CO2 from a point source (such as a smoke stack). The CO2 is then stored.

This book is largely about the people behind the development of DAC, rather than the scientific and engineering underpinnings of it.

One of the major themes of this book is that of technical innovation by competition.

Overall, I found this book to be thorough and detailed as well as very optimistic but their are problems with this book.

It takes a largely U.S.-centric approach to the development and prospects of DAC. There is no mention of DAC efforts in the EU, China, or India.

Barely mentioned is the requirement that captured CO2 will have to be stored in a depository that will not allow subsequent release of CO2 to the atmosphere.

Exactly when DAC is to be implemented is unclear. If we use it before we have switched to renewables, then there is no incentive to reduce CO2 emissions (which is bad). If we use it after we have switched completely to renewables, then DAC can be used to remove the CO2 emissions we have already put in the atmosphere since the Industrial Revolution (which is good).

These and related questions are left hanging, and leaves the reader wondering where all this leads too.

Finally, there are no illustrations in this book. I would have liked to have seen at least a diagram of how DAC happens, at least in theory.

In conclusion, this book is very optimistic about Direct Air Capture while ignoring problems with it.

XXXXX

(2023; introduction; 11 chapters; epilogue; main narrative 165 pages; notes; acknowledgments; index)

XXXXX

[Enid Wray · Rating 3 out of 5]

Very short, but very niche discussion - history, development and potential - for one very specific method of dealing with CO2 accumulations in the global atmosphere.

Interesting read.

[Alexandre Pittet · Rating 4 out of 5]

Comprehensive, engaging story of the Direct Air Capture