Review of Lefebvre, et al., Biomass residue to carbon dioxide removal: quantifying the global impact of biochar

Literature Review Series

Authored by Wil Burns, Co-Director, Institute for Carbon Removal Law & Policy, American University

To date, the vast majority of purchases of durable carbon dioxide removal have been for biochar, a process that can transform biogenic carbon dioxide into a far more stable form via the process of pyrolysis. Pyrolysis is a thermal process that, in the absence of oxygen, can deconstruct bio-polymers into, among other things, biochar, a charcoal-like substance that can securely store carbon for hundreds to thousands of years when applied to soil. Conversion of biomass to biochar can sequester 50% of initial carbon, compared to 3% associated with burning, or less than 10-20% after 5-10 years from biological decomposition.

Image Credit: Lefebvre, et al. The above image is a graphical abstract.

A number of studies in recent years have suggested that biochar potential could be much greater in the future, perhaps in the range of 3.5 GtCO2/yr., or up to 350 Gt during this century. However, to date, studies have focused on global or regional aggregate estimates. In a recently published study, researchers led by David Lefebvre of the University of British Columbia sought to extend these analyses by assessing the potential of biochar sequestration in each of 155 countries. The study restricts itself to the assessment of sequestration potential associated with biomass residue feedstocks in the contexts of agriculture, forestry wood residues, animal manure, and wastewater biosolids. The study also presumes that 30% of residues are left in the fields in the interest of maintaining long-term soil health.

Among the conclusions of the study are the following:

  • Four countries, all characterized by large populations, land areas, and agricultural sectors have the greatest potential, including:
    • China: 468 Mt CO2e/yr.
    • United States: 398 Mt CO2e/yr.
    • Brazil: 303 Mt CO2e/yr.
    • India: 225 Mt CO2e/yr.
  • North America and South America are characterized by a large number of countries with biochar sequestration potential of 25 Mt CO2e/yr., with bands of relatively low potential across North Africa into the Middle East, with low potential in portions of Europe and southern Africa.
  • 28 countries have the potential to sequester more than 10% of their CO2 emissions with biochar, with the largest number in Europe
  • The “conservative approach” of the study (including assessment of only recalcitrant carbon with permanence factors based on national averages) yielded an estimated carbon dioxide removal potential of 6.23% of total greenhouse gas emissions of the 155 countries in the study.

Notably, the researchers observed that its estimates didn’t take into account a number of potentially compelling co-benefits, such as potentially reducing emissions of methane and nitrous oxide, enhancement of crop yields and displacement of fossil fuels. Any effort to assess the potential costs and benefits of biochar deployment in individual countries, as well as globally, will require a more granular assessment of these factors, suggesting one potential research tributary flowing from this study.

Overall, this study could prove extremely helpful in helping to operationalize biochar programs nationally, and regionally, moving forward. It suggests that biochar could play an important role in the carbon dioxide removal portfolio of many countries.

Carbon Removal Meets Environmental Justice: A Fellow’s Perspective

Authored by Jake Ferrell, Carbon Justice Fellow at the National Wildlife  Federation

Set up in their on-site warehouse, company leadership gathered perhaps fifty people, myself included, around a large presentation screen to show what went into building and deploying their climate-saving direct air capture (DAC) technology. They presented their aims, a polished pitch: DAC modules widely deployed with low-costs, at commercial scale, and located in the desert somewhere so it wouldn’t bother anyone. A hand shot up – had they considered the environmental justice (EJ) dimensions of their projects? Doubts were voiced that projects would, in reality, be located so far away from communities, let alone sensitive wildlife and ecosystems. The question was shouted, barely audible in the cacophonous mechanical environment. “We didn’t think about that yet,” company leadership replied. “We’ve been focused on the engineering of building a DAC plant.”

A group of people pose for a photo inside a building.









The Carbon Removal Justice Fellows meet with members of the Senate Budget Committee on Capitol Hill. Photo credit: Jake Ferrell

The Carbon Removal Justice Fellowship was created to center equity and justice considerations in carbon removal policy. National Wildlife Federation partnered with American University’s Institute for Carbon Removal Law & Policy to co-run the program. The fellowship’s creators saw an opportunity to gather a diverse group of talented people to meet at the intersections of environmental justice and carbon removal in order to facilitate important conversations on how to avoid this industry becoming another harmful iteration of the status quo. The fellowship’s inaugural cohort was made up of folks working in environmental law, community advocacy for frontline communities, clean water, decarbonizing heavy industry, carbon removal social science, and more.

What is Carbon Dioxide Removal?

Carbon dioxide removal (CDR) is a strategy whereby CO2 is removed directly from the ambient air and sequestered in a form that prevents it from re-entering the atmosphere. CDR addresses the climate crisis by targeting excess atmospheric CO2, a result of societal industrialization. Examples of CDR range from natural solutions like reforestation to more technological processes like DAC.

Several people sit on couches and various seats in an office.

Fellows meet with representative offices on Capitol Hill. Photo credit: Jake Ferrell

Centering Environmental Justice in Carbon Dioxide Removal

The potential benefits of CDR include the prospect of addressing legacy emissions, and the ability to make room for self-determined development in places that might require steel, concrete, or other emissions-generating industries during the energy transition. The growing CDR industry, however, still has a series of challenges to grapple with regarding its energy demands, water use, climate-relevant scalability, economic cost, and transportation of CO2 from capture to sequestration sites. Additionally, this sector cannot afford to ignore the country’s long-standing legacy of racist pollution, siting injustices, and undelivered promises. Projects and communities are always inextricably intertwined, both economically and environmentally, so projects need to incorporate environmental justice considerations such as self-determination, informed consent, and mutual respect from the early planning stages of a project.

But environmental justice is more than listed principles – it is an active and variable movement with many facets, so it is vital that as the carbon removal sector experiences rapid growth, justice, conservation, and labor voices claim a seat at the table to be heard. Thus far, many active EJ organizations have been understandably critical of CDR conversations that do not appear to take seriously the social implications and historical legacies of adding more industrial projects in their communities. There is a risk that carbon removal provides an excuse for mitigation deterrence, or the postponing of society’s necessary transition away from fossil fuels. Many in the Carbon Removal Justice Fellowship carried forward this skeptical EJ ethos into conversations in the CDR space.

Urging the Industry to Consider its Impacts

The eleven Fellows managed to visit Washington, D.C., New York, NY, Laramie, WY, and Denver, CO within a packed 15 days in July. We talked to folks at organizations like the BlueGreen Alliance, Carbon180, Carbon Business Council, US Department of Energy, WE ACT for Environmental Justice, and World Resources Institute to name a few. The Fellows also spent two days engaging in CDR conversations on Capitol Hill. In my view, our purpose – the red thread guiding us through our manifold meetings – was to hold space, to parse through some of the complex issues at the intersections of EJ and CDR, and to challenge existing perceptions. In this last aspect we were especially successful, and success in this instance often meant tension and uncomfortable exchanges. But tension is often necessary for progress, and many participants across the program appreciated our candor.

Some of the Fellows’ recurring questions from the duration of the program include: What does it mean to center environmental justice in relation to carbon removal? What does it look like for a project to get enthusiastic consent from a community? How are a project’s community benefits determined, and who gets to make those decisions? What does an A+ on a project’s environmental justice and community benefits scorecard look like? How do we move from well-intentioned plans to legally enforceable agreements? Who is accountable to whom, and where does the buck stop?

While historic policy related to carbon removal has been passed and big announcements like the $1.2 billion dollars for DOE’s DAC Hubs continue to roll out, the Carbon Removal Justice Fellows will continue to wrestle with these questions and others in the weeks and months to come. Those two weeks in the July heat mark the beginning of our ongoing engagement with carbon removal and environmental justice.

A group of people pose for a photo outside.

Photo credit: Jake Ferrell

Such an impactful group could not have come together without Dr. Simone H. Stewart and Shannon Heyck-Williams at the National Wildlife Federation, and Dr. Simon Nicholson and Jenn Brown at the Institute for Carbon Removal Law and Policy at American University, most of whom participated alongside the cohort during the fellowship.