How scalable are our CDR solutions?

Executive Summary

The world’s carbon dioxide removal (CDR) policies are organized around the premise that a portfolio of solutions like direct air capture, enhanced rock weathering, ocean alkalinity enhancement and biochar can combine to reach 10 gigatons of annual CO2 removal capacity by around mid-century. Some studies have suggested this goal might be within reach given sufficient investment, technological progress and favorable conditions; other studies have cast doubt. For the most part, however, policymakers have been slowly developing and critiquing CDR strategies with this removal goal and timeline in mind; this has been the CDR community’s common truth.

But what if this truth is wrong and we end up needing more than 10 gigatons per year (Gt/y) of CDR, maybe even much more? If our net fossil fuel emissions remain high — which is a reasonable assumption (arguably more reasonable than assuming they will drop precipitously in coming years) — then stabilizing temperatures will require more CDR than we’re planning to deploy, and more than our current CDR portfolio can provide. A portfolio capable of reaching 10 Gt/y is not necessarily capable of reaching 60 or 100 Gt/y. Most of our solutions have limited physical removal potential, and several compete for the same finite resources, meaning their individual potentials cannot simply be added together. Indeed, evidence suggests that our current portfolio cannot grow significantly beyond 10 Gt/y without starting to rely primarily on direct air capture and ocean alkalinity enhancement, and these solutions will likely not be able to make a climate-relevant contribution to our CDR efforts for decades to come.

Also concerning is whether our current CDR solutions portfolio will be affordable, both at the 10 Gt/y scale and beyond if needed. Lawrence Livermore’s 2023 Roads to Removal report estimated the United States could remove one gigaton of CO2 annually for approximately $130 billion. Extrapolating this estimate — not as a forecast, but for perspective — 10 gigatons of annual removals might cost the world $1.3 trillion per year. Although technological progress may lower costs, many solutions will still require enormous investments in energy, infrastructure, and ongoing operations, and substantial economies of scale are far from assured. Sustaining expenditures of this magnitude would be difficult for most governments, and increasingly unrealistic if much higher levels of CDR are required.

Beyond physical capacity and cost, our current solutions also face substantial feasibility challenges involving permanence, verification, environmental impacts, regulation, and public acceptance. These obstacles may become more difficult as deployment expands, especially if removals must be sustained for generations. As well, we must move beyond the goal of merely stabilizing our temperatures and plan for how we will eventually restore them. Since even current levels of warming are causing ongoing damage to human civilization, restoring temperatures to safer levels within a reasonable period of time must become the new normal for CDR policy.

In order to ensure our CDR solutions keep pace with our carbon removal needs, we therefore need to reexamine both our portfolio and our approach to supporting it. This might involve accelerating improvements to existing CDR solutions; it might also mean developing approaches to deploy lower-yield solutions more broadly to make a larger contribution to our CDR efforts, or even searching for fundamentally new CDR approaches that are more scalable, effective and affordable. Scalability and the ability to sustain high removal rates for generations must become design priorities.

None of this is an argument for abandoning today’s CDR solutions. We need them, and continued investment and experimentation will hopefully substantially improve their performance. But trusting the ability of our present solutions portfolio to scale to 10 Gt/y is already a leap of faith; getting very far beyond this level will quite possibly be physically and financially impossible. We need to shift our focus from simply building a larger CDR industry to developing a solutions portfolio legitimately capable of meeting whatever CDR requirements the future may have in store.

This post has been republished with permission from the Vancouver Process website. Photo credits: Climeworks Mammoth site in Iceland. Photo courtesy of Climeworks.