Sciences, Publics, Politics: Carbon Removal Is No Quick Fix
For nearly half a century, the Drax power station in Yorkshire, England, was the country’s largest coal-powered electricity generator and a giant source of heat-trapping carbon dioxide pollution. But in recent months, Drax has transitioned from coal to burning wood pellets as engineers test methods for efficiently capturing the carbon dioxide produced and burying it underground, in an effort to create “negative emissions.”
Among the pathways that the Intergovernmental Panel on Climate Change (IPCC) has identified for achieving the temperature targets stipulated by the 2015 United Nations’ Paris Agreement, only a handful rely exclusively on efforts to reduce or “mitigate” greenhouse gas emissions. The majority of climate strategies, instead, require the massive deployment of carbon removal and storage methods, also referred to as “negative emissions technologies,” designed to clean up existing carbon dioxide in the atmosphere.
Approximately 20%–40% of annual greenhouse gas emissions today come from sources, such as agriculture and transportation, that will be exceedingly difficult to eliminate. Theoretically, one advantage of pursuing carbon removal strategies is that reducing the climate impacts of these and other tough-to-decarbonize sectors does not require that human-caused emissions cease all together, but that the net total of emissions is less than or equal to the amount captured and stored by natural and human-made “sinks.”
Although a range of carbon removal methods exist, most IPCC scenarios anticipate the building of thousands of bioenergy and carbon capture and storage (BECCS) plants similar to England’s Drax installation.Yet BECCS as a technology remains at the preliminary research and assessment stage, with a great deal of uncertainty regarding technical feasibility, cost, risks, and social acceptability. Other carbon removal methods such as direct air capture, reforestation, and soil sequestration face similarly formidable challenges. Because of their speculative nature, relying on carbon removal to accomplish the goals of the Paris Agreement is a “trick that comes perilously close to magical thinking,” writes The Economist.
Still, carbon removal options remain politically appealing. The scientific models relied on by the IPCC to estimate pathways for meeting Paris Agreement goals assume that the discounted costs of negative emissions technologies will eventually be less than the current cost of relying on existing fossil fuel mitigation options. The enthusiasm for carbon removal also reflects a tendency to favor “techno-fixes” as a means to bypass difficult politics. If it is too contentious and costly to rapidly transition away from fossil fuels, why not invent new technologies and methods (always “just around the corner” or “in the near future”) that sidestep contentious debate?
Overlooked in this line of thinking is that the pursuit of planet-wide carbon removal will likely introduce its own set of intractable controversies. As I argue in a new report by the Institute for Carbon Removal Law and Policy, building a vast industrial negative emissions infrastructure that competes with agricultural production and poses threats to land rights and local ways of life is a strategy guaranteed to produce more politics, not less. All-too-familiar clashes are likely to surface, over the proper role of markets versus government, international governance versus national autonomy, fairness and equity, and the balancing of benefits against precaution in the face of risks, uncertainty, and costs.
Making risky bets
Following the 2015 Paris summit, the United Nations invited the IPCC to assess hypothetical pathways for achieving the end-of-the-century goal of holding global warming to two degrees Centigrade (2°C) above preindustrial levels and to strive for a 1.5°C limit. The resulting IPCC special report, Global Warming of 1.5°C, released in 2018, relied on research that used integrated assessment models to estimate these pathways, blending scientific understanding of the Earth system with a variety of societal factors related to population growth, the economy, human behavior, and energy use.
BECCS features so heavily in these models because its estimated cost is low relative to other anticipated options and because modelers are still developing methods for representing direct air capture and other carbon removal methods in their projections. But to meet the optimistic assumptions that underpin the models, some estimates find that biomass for fuel would need to be grown across 740 million to 1 trillion acres of land—a combined area larger than India, encompassing 40% of current global cropland.
To facilitate this historically unprecedented shift in land use, and to prevent food shortages, most IPCC scenarios also assume technological breakthroughs that enable vast improvements in agricultural yield, major reductions in food waste, and the mass adoption of plant-based diets. Critics justifiably argue that these assumptions are not only unrealistic but risky. Nor do the IPCC scenarios account for the implications of BECCS in the real world: to date, there remains little analysis of the transportation challenges related to the rapid scale-up of bioenergy, which either needs to be grown, burned, and sequestered near major cities and industries, or transported long distances, a process that is both costly and carbon-polluting. At the Drax plant in England, for example, wood pellets are transported from the United States by truck, train, and ship.
The imaginary technology of BECCS, the climate scientists Kevin Anderson and Glen Peters warn, provides a false sense of complacency. Incorporating BECCS into climate policy maintains the illusion that countries remain committed to the temperature targets established in the Paris Agreement, even as these countries remain dependent on fossil fuels. Maintaining this fiction, Anderson and Peters assert, is far more politically appealing than pursuing the much more contentious route of enacting policies aimed at rapid and deep cuts in emissions. The risk of a moral hazard is high: the massive deployment of BECCS may eventually be possible, but it will take decades to know for sure. If the challenges prove too great, “future generations may be stuck with substantial climate change impacts, large mitigation costs, and unacceptable trade-offs,” the climate scientists Chris Field and Katharine Mach write.
Looming land wars
Direct air capture with carbon storage (DACCS) is a second carbon removal option that has received significant attention. Researchers at Carbon Engineering, a Canadian firm that operates a small-scale, pilot carbon dioxide capture plant in British Columbia, estimated in a 2018 study that their patented process would be able to pull carbon dioxide out of the air at a cost between US$94 and $232 per ton of carbon dioxide, depending on the details of implementation and assumptions about financing and energy costs.
This broad estimate, if plausible, is a major advance over previous projections that had priced the cost of various schemes between US$640 and $819 per ton of carbon dioxide. But establishing a market for carbon capture still depends on implementing carbon pricing policies. Such measures face strong opposition across all countries, no matter their announced commitment to reducing emissions. “There is no way we are beating oil from the ground in a head-to-head competition without regulation,” says Harvard University’s David Keith, who founded Carbon Engineering with financing from Microsoft cofounder Bill Gates.
Opinion surveys conducted in various countries reveal that most people are mostly unaware of various carbon capture technologies, but voice reservations when asked their opinion, perceiving the technology as “unnatural” and “risky.” Providing more information about carbon capture tends to strengthen, rather than lessen, opposition. In locations where trials have taken place to capture and store carbon from fossil fuel power plants, the projects have been met with opposition by local activists, suggesting that future debates over the large-scale deployment of DACCS may play out in similar ways.
Public opinion is also likely to vary by the proposed uses of direct air capture. In 2019, Occidental Petroleum and Chevron invested in Carbon Engineering, with plans to build a full-scale DACCS plant in Texas to provide carbon dioxide for enhanced oil recovery. In this process, carbon dioxide extracted from the atmosphere is injected into oil fields to scrape out more oil than possible using conventional methods. Several environmental groups strongly oppose the use of DACCS on behalf of enhanced oil recovery, arguing that it “greenwashes” fossil fuel development as “carbon neutral.”
At the local level, opposition is likely to be especially intense given the unprecedented amount of land needed to operate a full-scale plant. For example, in the “liquid solvent system” design for direct air capture, the array of “contactors” that capture air from the atmosphere must be arranged around a centralized regeneration facility where the air is heated, filtered, and compressed, producing carbon dioxide to be repurposed, transported, sequestered, or all three. Powering such a system, like all DACCS designs, necessitates a dedicated source of electricity generation with the most likely option a natural gas plant combined with solar or wind generation or both.
Given these requirements, a 2019 National Academies of Sciences, Engineering, and Medicine report estimated that a liquid solvent system plant capable of capturing one million tons of carbon dioxide per year would need to be between 14,500 and 25,500 acres in size, or roughly 22–40 square miles, a gargantuan tract that at the low-end is 433 times larger than the average natural gas plant in the United States. Deploying just 100 liquid solvent system-designed plants would take up a landmass equal to or greater than the size of Delaware. (And this would absorb only a fraction of the 36 billion tons of carbon dioxide currently emitted into the atmosphere annually.) For the alternatively designed “solid sorbent system” DACCS plants, the report estimated a land footprint of 500 to 2,450 acres, or roughly 0.8–3.8 square miles, which is still 17–81 times larger than today’s average natural gas plant.
A third set of prominent carbon dioxide removal methods, known collectively as terrestrial carbon removal and sequestration, have for years received attention for their possible climate benefits. These so-called natural climate solutions include reforestation, the restocking of existing forests and woodlands; afforestation, the planting of new forests where none previously existed; and soil sequestration through more sustainable agricultural practices.
Yet success in the decades-long efforts to promote the widespread adoption of sustainable forestry and agricultural practices has proved elusive, despite the well-financed efforts of international conservation groups in regions such as the Amazon and South Asia. The storage of carbon dioxide through these methods would also compete directly with the demand for land needed by DACCS and BECCS. Natural climate solutions are also not guaranteed to be permanent; wildfires, logging, land use changes, and other damage to ecosystems release heat-trapping pollution back into the atmosphere.
The IPCC has performed an “important legitimating function for the speculative technology of BECCs,” write the sociologists Silke Beck and Martin Mahony. The IPCC pulled carbon removal technology “into the political world, making previously unthinkable notions … mainstream and acceptable.” But technical feasibility was given priority over questions of the societal desirability of various carbon removal methods. As a consequence, scientific claims made by the IPCC about the future have become political interventions, shaping the potentially irreversible path of policy decisions.
“In less than a decade, negative emissions went from an afterthought to being absolutely essential to international climate policy,” the political scientist Roger Pielke Jr. recently observed in Issues. “No government had actually debated the merits of BECCS, there were no citizen consultations, and very little money was being devoted to research, development, or deployment of negative emissions technologies. Yet there it was at the center of international climate policy.”
Given the perceived urgency of climate change, carbon removal methods have been talked about only in the most ambitious of schemes, rather than in a more useful frame of “right-sized” approaches. “Many candidate [carbon removal] technologies have the potential to be the foundation for strong enterprises, capturing many millions of tons of carbon dioxide per year, in locations where each approach makes sense technically and economically, with a favorable mix of co-benefits and side effects,” the climate scientists Field and Mach noted. “It is at much larger scales”—billions of tons of carbon dioxide per year—“that the technologies warrant concern.”
Grandiose thinking about carbon removal must be replaced by a constant questioning process that draws on a plurality of perspectives. How, for example, should research and innovation take place? What might be the unintended consequences of a technology? Who gets to decide on the deployment of carbon removal technologies and who is responsible for addressing the problems they create? Which values, interpretations, and worldviews matter? Will carbon removal technologies be deployed to benefit the public interest or on behalf of special interests? How should this conversation, and the disagreements that ensue, be structured? What are the principles and criteria that should apply?
Numerous social science studies demonstrate that on complex decisions, such as those involving negative emissions technologies, individuals (including experts) are likely to make poorer decisions and think less productively if conventional wisdom is defended to the exclusion of dissenting voices. In contrast, exposure to dissent, even when such counterarguments prove to be wrong, tends to broaden thinking, leading individuals to think in more open ways, in multiple directions, and in consideration of a greater diversity of options, recognizing flaws and weaknesses in positions. Facilitating constructive disagreement around carbon removal strategies will depend on institutions and funders making a sustained commitment to the intellectuals and journalists capable of exposing faulty assumptions and expanding the range of options.