CDR Methods

CDR methods

The umbrella term negative emission technologies (NET) describes different nature-based and technological methods to remove CO₂ from the atmosphere and store it long term (so-called carbon dioxide removal (CDR) methods). CDR methods include the targeted expansion of the storage capacity for carbon in plants and soils, the enrichment of recycled and carbon-storing building materials and their reuse, the capture of CO₂ by means of technical and chemical processes from the ambient air or from industrial processes, and the capture in long-term storage sites.

Thanks to innovative research projects and companies in the field of CDR methods, Switzerland is currently a leader in the development and application of some of these processes, such as the production of carbon-negative cement or the direct capture of carbon from the air. However, the further development, market introduction and scaling of these approaches face many challenges. On the one hand, it is difficult to acquire the necessary financial resources for research and development, to find implementation partners in industry and to obtain permits for test facilities. On the other hand, the further expansion of processes that are already marketable requires an expansion of the supply of renewable energies, the development of sustainable storage options and functioning logistics for biomass and carbon.

Last but not least, the public must be informed about the advantages, disadvantages and possible risks of the different processes, and a broad discourse about corresponding uncertainties and ambiguities must be initiated. In order to ensure a sustainable expansion of NET, this process should also include the political decision-makers who are responsible for ensuring a conducive political and legal framework in the future.

Currently, the expansion of the following CDR methods is being discussed:

Afforestation + Reforestation

Forest management measures that optimize and increase the CO₂ uptake of woodlands by expansion, protection or reforestation. A sustainable management ensures that the carbon is bound in the soil and living biomass of healthy forests for a long time. Further, this approach can include using wood for long-lived products or energy production in cascaded use.

Biochar + Soil Carbon Sequestration

Conversion of biomass (e.g. harvest residues) into mineral-rich charcoal at high temperatures and in the absence of oxygen (i.e. pyrolysis), making it resistant to decomposition. Allows to sink C in agricultural soils, with various co-benefits. This approach includes further agricultural practices that aim to increase the soil carbon content and thus uptake of CO₂ from the atmosphere. Biochar is also used outside agriculture. The production and storage of biochar is also called pyrogenic carbon capture and storage (PyCCS).

Direct Air Carbon Capture & Storage (DACCS or DAC+S)

Removal of CO₂ from ambient air through various chemical or engineering processes, e.g. adsorption, methanation or via hydroxide solutions (powered by residual heat or renewable energy). Captured CO₂ may then be stored long-term, e.g. by injecting it into depleted oil and gas fields or saline aquifers, or used in consumer goods and other applications.

Enhanced Weathering + Carbon Uptake in Cement

Application of minerals, such as rock powder, that naturally absorb CO₂ by chemical weathering, in terrestrial or aquatic systems. Depending on the used rock, nutrients are released and soil properties can be improved. This approach also includes enhanced CO₂ uptake in cement by means of concrete recycling technologies, e.g. the carbonation of crushed concrete materials, that allow long-term storage of captured CO₂ in built structures.

Bioenergy with Carbon Capture + Sequestration (BECCS)

Integration of carbon removal technologies in a wide range of industrial processes that convert biomass (i.e., put simply, carbon stored by/in plants) into products, such as fermentation, gasification or combustion. Carbon captured in e.g. combined heat and power plant, in biogas plants, the paper and pulp industry or during ethanol production may then be stored long-term.

Cultivation + Restoration of Wetlands

As a natural carbon sink, wetlands generate biomass that conserves carbon dioxide, e.g. through the formation of peat in raised bogs. Thus, cultivating and restoring wetlands, peatlands and coastal habitats have the potential to combine long-term carbon absorption and storage with nature conservation.

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Literature Focusing on Switzerland

Dossier Negative CO2-Emissionen
BAFU-Magazine “die umwelt” 2022

Overview and in-depth reports on current developments and actors in Switzerland

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Carbon Capture and Storage (CCS) and NET
Swiss Carbon Removal Platform (2022)

How they can gradually contribute to the long-term climate goal – CDR Swiss blog article on the Federal Council’s report

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The Role of Atmospheric CDR in Swiss Climate Policy
Risk Dialogue Foundation (2018)

This report summarizes the role of all relevant CDR approaches in Switzerland and their potential for the strategic goals set for 2050.

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Negative emissions: the main approaches
Federal Office for the Environment (2020)

A factsheet summarizing all relevant CDR approaches and the role they could play for Switzerland.

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Long-term climate strategy to 2050
Swiss Federal Council (2021)

The 2021 long-term climate strategy of Switzerland relies on a combination of steep reduction pathways with negative emissions to reach the Net Zero target.

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«Der Untergrund kann viel…»
BFE-Magazin (2021)

Interview with Gunter Siddiqi on the role of Switzerland’s underground for carbon capture and storage and geothermal power production.

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Negative CO2-Emissionen
Schweizer Bauer (2021)

News article on the role of CDR in Switzerland.

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Selected Research + Background Information

The ABC of Governance Principles for Carbon Dioxide Removal Policy
Honegger et al., 2022

Political science publication on the principles and rationale for laws and measures around CDR.

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Negative emissions—Part 1: Research landscape and synthesis
Minx et al. (2018)

Scientific review paper summarizing recent research on CDR and negative emissions technologies.

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Technologies and policies to decarbonize global industry: Review and assessment of mitigation drivers through 2070 
Rissmann et al. (2020)

Scientific review paper discussing a broad range of mitigation approaches based on recent research, including substituting low-carbon for high-carbon materials and carbon capture.

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Climate scientists: concept of net zero is a dangerous trap 
Dyke, Watson and Knorr (2021)

Critical opinion piece by climate scientists on the concept of ‘net zero’ – and the risks of betting on CDR for climate change mitigation.

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Global Warming of 1.5 °C 
Intergovernmental Panel on Climate Change (2018)

An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and the role of CDR for reaching the 1.5 °C target.

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Policy Brief: Negative Emissions
Mercator Research Institute on Global Commons and Climate Change (2016)

The 1.5°C target significantly reduces the carbon budget compared to the 2°C target. New technologies aim to remove already existing carbon dioxide from the atmosphere—but also entail serious risks.

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Net expectations: assessing the role of carbon dioxide removal in companies’ climate plans

Greenpeace UK (2021)

Detailed background information, assessments & recommendations for action on the topic of NET, in particular on the role of negative emissions in corporate climate plans. 

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