Carbon Dioxide Removal (CDR) - An overview
Understanding Carbon Dioxide Removal (CDR)
Carbon dioxide removal (CDR) is a critical strategy to mitigate climate change by reducing the concentration of carbon dioxide (CO2) in the atmosphere. As greenhouse gas emissions continue to rise, CDR technologies are gaining prominence as a necessary tool to achieve climate stabilization goals.
CDR can be broadly categorized into two main types: technological and biological. Technological CDR involves the use of engineered systems to capture and store CO2, while biological CDR leverages natural processes to remove and sequester CO2.
Direct Air Capture (DAC)
A view of a computer-rendered image of Climeworks' Mammoth direct air capture plant
How it works: DAC systems use specialized filters or sorbents to capture CO2 directly from the atmosphere. The captured CO2 is then stored or used for various applications.
Links: Climeworks, Carbon Engineering, Global Thermostat, Carbon Clean, Carbfix, CarbonCure, CarbonQuest
Ocean Alkalization
The mesocosms are towed towards the pier by inflatables
How it works: Ocean alkalization involves adding alkaline substances, such as limestone or seawater, to the ocean to increase its carbonate alkalinity. This process can help counteract ocean acidification and enhance the ocean's ability to absorb CO2 from the atmosphere.
Links: SeaChange, Blue Carbon, Ocean Engineering, Ocean Solutions, Blue Ocean Carbon
Mineral Carbonation
Carbonaide's system cures concrete in a CO2-rich environment to capture the carbon, and does not require high-pressure injection or other additional steps.
How it works: Mineral carbonation involves reacting CO2 with minerals, such as olivine or basalt, to form stable carbonate minerals. These minerals can be stored underground or used as construction materials.
Links: CarbFix, Olivine, Carbon Mineralization, Green Concrete
Enhanced Weathering
How it works: Enhanced weathering involves accelerating the natural weathering process of silicate rocks by grinding them into fine particles and spreading them over large areas. The exposed surface area increases the rate at which the rocks react with atmospheric CO2.
Links: Enhanced Rock Weathering, Weathering Power, Silicate Weathering, Accelerated Weathering, Carbon Negative Rocks, Weathering Solutions, Climate Restoration, Natural Carbon Capture
Bioenergy with Carbon Capture and Storage (BECCS)
An aerial panorama view of Drax power station showing biomass storage tanks and carbon capture capabilities. Credit: Shutterstock – Clare Louise Jackson
How it works: BECCS involves growing biomass, such as trees or crops, capturing the CO2 released during biomass combustion, and storing it underground. This process can achieve negative emissions if the biomass is grown sustainably.
Links: Drax, Vattenfall, Sinopec, Engie, Ørsted, Bioenergy
Membrane Gas Separation
First-of-its-Kind Helium Purification Facility with Hybrid Membrane/PSA Technology
How it works: Membrane gas separation uses porous membranes to selectively separate CO2 from other gases in a mixture. This technology is often used in industrial settings to capture CO2 from flue gas.
Links: Sulzer, Siemens, Honeywell, Koch Membrane Systems, GE Water, Air Liquide, Praxair
Afforestation and Reforestation
How it works: Planting trees and restoring forests helps to sequester CO2 through photosynthesis.
Links: The Nature Conservancy, World Resources Institute, Terya.co, Rainforest Alliance, Arbonics, Arbor Day Foundation, Conservation International, Forest Stewardship Council, Trees for the Earth
Blue Carbon Ecosystems
How it works: Protecting and restoring coastal ecosystems, such as mangroves, seagrass meadows, and salt marshes, helps to sequester carbon in their sediments.
Links: The Nature Conservancy, NatureServe, Wetlands International, Blue Carbon Initiative, Conservation International, Ocean Conservancy, Coastal Restoration, Mangrove Alliance, Seagrass Conservation
Soil Carbon Sequestration
How it works: Implementing agricultural practices that improve soil health, such as cover cropping, no-till farming, and compost application, can help to increase soil carbon storage.
Links: Rodale Institute, Soil Health Institute, Kiss the Ground, Regenerative Agriculture, Carbon Farming Solutions, Soil Carbon Initiative, Healthy Soils, Soil Carbon Sequestration
Ocean Fertilization
How it works: Adding nutrients, such as iron, to the ocean can stimulate phytoplankton growth, which can absorb CO2 from the atmosphere. However, this practice is controversial due to potential environmental impacts.
Links: Ocean Iron Fertilization, Iron-Fertilization Experiments, Marine Geoengineering, Ocean Nutrient Addition, Ocean Carbon Management
Biochar Production
How it works: Biochar is a charcoal-like material produced from the pyrolysis of biomass. It can be added to soil to improve its structure and carbon storage capacity.
Links: Biochar International, Biochar Research Network, Biochar Solutions, Biochar Academy, Biochar Foundation, Biochar Producers, Biochar Projects
Forest Carbon Offset Projects
How it works: These projects protect and restore forests to capture and store carbon dioxide (Carbon Capture & Storage or CCS) and offset emissions from other activities.
Links: Tree.ly, Verra, Gold Standard, American Carbon Registry, Climate Action Reserve, Ecosphere Plus, Forest Carbon Credits
Ecosystem Restoration
How it works: Restoring degraded ecosystems, such as wetlands, grasslands, and forests, can help to increase their carbon storage capacity.
Links: NatureServe, Wetlands International, Ecological Restoration, Habitat Restoration, Biodiversity Conservation, Landscape Ecology
Conclusion
Carbon dioxide removal technologies offer a promising avenue for mitigating climate change. Both technological and biological approaches have the potential to make a significant contribution to reducing atmospheric CO2 levels. However, the effectiveness and scalability of these technologies will depend on a variety of factors, including technological advancements, economic viability, and policy support. As the world continues to address the challenges of climate change, CDR will likely play an increasingly important role in achieving a sustainable future.
