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Technological Carbon Removal in the United States

The purpose of this working paper is to explore the potential for technological carbon removal in the United States, identify needs likely to arise on the pathway to large-scale deployment, and consider ways to begin addressing those needs. This working paper is part of a World Resources Institute (WRI) publication series CarbonShot: Creat­ing Options for Carbon Removal at Scale in the United States. The series presents findings from a WRI-led assessment of needs for scaling candidate carbon removal approaches and technologies in the United States. This paper focuses on the technological options, including bioenergy with carbon capture and storage (BECCS), direct air capture with storage (DACS) and frontier technologies. It concludes by describing a series of near-term policy ideas that could help begin to address these needs in the United States.

Key Findings

Executive Summary

Highlights

  • The ambitious emissions reduction measures modeled in most global emissions pathways are not enough to achieve the Paris Agreement targets for limiting temperature rise. In these pathways, it is also necessary to undertake efforts to remove carbon dioxide (CO2) from the atmosphere at the gigaton scale—billions of metric tons per year globally.
  • This paper explores candidate technological approaches for carbon removal in the United States, including bioenergy with carbon capture and storage (BECCS); direct air capture and storage (DACS); and several frontier technologies, including biochar, plant selection or engineering, enhanced weathering, and seawater capture.
  • Deploying each of these technologies at a large scale will require addressing a set of key needs related to technological maturity and cost reduction, enabling infrastructure and markets, and better understanding of climate benefits and ancillary effects. Ultimately, all carbon removal technologies will depend on sustained public support, including funding.
  • This paper illustrates policy ideas that could begin to address these needs and create an environment that helps accelerate the development and deployment of promising technologies and the surfacing of new ones.

Background

Heightened abatement of greenhouse gas (GHG) emissions is needed to achieve the goals of the Paris Agreement and limit warming to well below 2˚C, with efforts to limit warming to 1.5˚C, to avoid the most dangerous climate impacts. Furthermore, most scientific estimates show that to keep these goals within reach, the global emissions trajectory must not only reach net-zero1 by the second half of this century but also continue downward into net-negative emissions. Global climate models therefore illustrate the need to pursue both aggressive emissions reductions and significant deployment of carbon removal.2 They rely upon carbon removal approaches to offset the last remaining GHG-emitting activities that are too challenging or expensive to eliminate, and to compensate for any temporary overshoot of temperature goals.

Carbon removal is the process of removing CO2 from the atmosphere and storing it. It is distinct both from solar radiation management, which seeks to reflect incoming sunlight to reduce warming rather than remove carbon from the atmosphere, and from carbon capture and storage (CCS) from point sources of emissions such as fossil-fueled power plants or industrial facilities. Approaches to carbon removal traverse a spectrum from land management approaches to technological options, including carbon management in agricultural soils, forests, and agroforestry; BECCS3; DACS; and frontier technologies such as biochar, plant breeding or engineering,4 enhanced weathering, and seawater capture. The intention of carbon removal is to store CO2 in plants, soils, and oceans, as well as nonbiologically in geological formations and products (e.g., building materials), augmenting the net transfer of carbon from the atmosphere that naturally takes place as part of the carbon cycle (Minx et al. 2018). In some cases, storage is permanent; in others the CO2 may return to the atmosphere over time.

Carbon removal is intended to help address global warming by reducing atmospheric concentrations of the primary greenhouse gas, CO2, accelerating or augmenting the net transfer of CO2 from the atmosphere.

To-date, a gap exists between the need for rapid emis­sions reductions to stabilize the climate at the tempera­ture targets established in the Paris Agreement and the availability of cost-effective measures that can provide those reductions (UNEP 2017). Advancements in carbon removal can help close that gap. However, each carbon removal approach available today faces its own challenges, potential pitfalls, and limitations. The full potential of each remains uncertain. Given this uncertainty, a portfolio of approaches and technologies could yield greater oppor­tunities for achieving large-scale carbon removal (Minx et al. 2018; Fuss et al. 2018).

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