Road to Removal: A blueprint for yanking billions of tons of CO2 out of our atmosphere

It'll also cost billions, but perhaps a price worth paying?

Let's say that you and your political leaders are committed to reducing the effects of the "greenhouse gasses" such as carbon dioxide (CO2) and methane (CH4) that are indisputably toasting our Earth.

In this perfect world, you and your political gros fromages are also firmly committed to "decarbonization" — that is, reducing the amount of greenhouse gasses produced by energy, transportation, industry, agriculture, and other critical economic sectors.

Good for you. But there's one big ol' problem. As Jennifer Pett-Ridge of the US's Lawrence Livermore National Laboratory (LLNL) explained during her presentation at the annual meeting of the American Geophysical Union in San Francisco (covered previously here and here):

We can decarbonize and decarbonize and decarbonize, and we're still not going to be be able to do enough.

As a hirsute hippie lounging in AGU23's host city might have said during 1967's Summer of Love, "Bummer, man."

But it's true. Any sober analysis of how to reduce greenhouse gas emissions enough to reach the stated goal of a mere 1.5°C of global warming by 2050 acknowledges that decarbonization alone will not be sufficient to reach and then sustain that benchmark. What's needed beyond mere decarbonization is a concerted effort to suck CO2 out of the sky in a process called "carbon capture, utilization, and sequestration" (CCUS).

The amount of CO2 needed to be removed from the atmosphere is not trivial. In 2021 the US Department of Energy launched its Carbon Negative Shot, part of its set of Energy Earthshots initiatives, which established a goal of identifying and scaling technologies that could remove at least a billion metric tons of CO2 from the atmosphere per year at an average cost of under $100 per metric ton removed.

To be sure, one billion metric tons is a lot of CO2, but it's only a small fraction of the 36.8 billion metric tons that we earthlings pumped into the atmosphere last year. But it's important to note that even if we, as Pett-Ridge said, "decarbonize and decarbonize and decarbonize," we'll never get that annual emissions figure down to zero, seeing as how there are some industries — think air travel and agriculture, for example — that will be fiendishly difficult if not impossible to fully decarbonize.

So even after decades of radical decarbonization, we're still going to have to deal with at least that minimum of one billion metric tons per year of CO2 that we will need to slurp from the troposphere. What to do?

Well, the other week, Pett-Ridge and her team, centered at LLNL but drawing from expertise across the US, released a thorough study of how we might accomplish that in America, in a report titled, "Roads to Removal," which explores in hundreds of pages of excruciating detail a county-by county analysis of American opportunities — a "smörgåsbord of options," as she put it — for removing CO2 from the atmosphere. We're talking over 3,000 American counties. We're talking one serious smörgåsbord.

The downloadable tome focuses on four main classes of techniques to suck current and future carbon dioxide from the atmosphere, and how well-suited each US county is suited to accomplish them:

  • Increasing forests and improving forest-management practices
  • Improving soil management on croplands
  • Capturing CO2 in biomass, then converting it into new products or permanently sequestering it
  • Capturing CO2 directly from the air using "direct air capture" hardware powered by renewable energy

According to Pett-Ridge, the first two of those methods, what she calls "ecological solutions," could remove 100 million metric tons of CO2 today — if employed. But the remaining 900 million tons? She admits that to get rid of them will require substantial investments in the development of direct air capture and biomass conversion technologies, which, she freely admits, "… is going to take a massive amount of financial investment."

Of those two technologies in need of investment, Pett-Ridge was particularly bullish about biomass carbon removal and storage, or BiCRS, which is pronounced like one's petty arguments with one's significant other. "We have a lot of waste," she said. "We have a lot of biomass that's just pure municipal solid waste, agricultural residues, that we burn, that we let decompose. We could do useful things with that material." What contribution to the 900 million missing metric tons could BiCRS contribute? Pett-Ridge estimates up to a full 800 million metric tons, "But obviously we'd need to build facilities to process that biomass and capture carbon while doing so," she admitted.

The LLNL group estimates that the ongoing cost of all four classes of techniques when up and running would be somewhere in the range of $130 billion per year beginning in 2050. That may sound like a lot — well, it is a lot — but Pett-Ridge reminded her audience that it's about one half of one per cent of America's current Gross Domestic Product (GDP). "We think it's on the order of what we spend on food waste and trucking garbage around," she said.

In addition to the techniques meticulously detailed in Roads to Removal, the team also noted that there are also what Pett-Ridge described as "roads not traveled" — decarbonization technologies and techniques that include enhanced weathering of silicate rocks, peatland and coastal wetland restoration, enhancing ocean alkalinity, and "fertilizing" the ocean with iron, nitrogen, and phosphorus. As is likely true with each and every scientific study you may have encountered, one conclusion is: "Much more research needs to be done."

There's no getting around the fact that a trip down the Road to Removal will be an expensive one. But with the rapid increase in costly droughts and wildfires, plus the increasing billions of dollars lost annually due to extreme weather events that robust attribution science proves are exacerbated by global warming, perhaps it's a journey we can't afford not to take. ®

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