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Carbon Dioxide Removal - Knowledge Hub was developed as part of the Horizon2020-ERC project GENIE. Visit the project page for more information.
Carbon dioxide removal (CDR) refers to human activities that capture CO2 from the atmosphere and store it durable in geological, land or ocean reservoirs, or in products. This includes human enhancement of natural removal processes, but excludes natural uptake not caused directly by human activities. CDR technologies vary in terms of their state of development, durability, costs, benefits and side-effects.
Afforestation and reforestation consists of restoring areas where trees have been cut down or degraded (reforestation) or planting trees where there were previously none (afforestation). Trees remove CO2 from the atmosphere during their growth and store it in living biomass.
Bioenergy with carbon capture and storage consists of converting biomass (e.g. farmed bioenergy crops, forests, residual biomass or industrial organic waste) into energy (usually through burning), capturing the resulting CO2 and storing it underground in geological reservoirs. The bioenergy needs to be provided at zero or low carbon emissions (i.e. as much additional CO2 needs to be sequestered when growing the feedstock as is released during conversion). Because CO2 is captured during the biomass growth and subsequently stored underground, BECCS leads to a removal of CO2 from the atmosphere.
Biochar is created via the pyrolysis of biomass (i.e. the degrading biomass with heat in the absence of oxygen). Biochar is added to soils, increasing carbon stocks and holding carbon for hundreds to thousands of years.
Blue carbon refers to the restoration of coastal wetlands, salt marshes, seagrass meadows and mangrove forests. These ecosystems capture and store CO2 in living biomass, as well as in marine sediments.
Direct air carbon capture and storage uses chemical processes to absorb CO2 from the atmosphere. The CO2 is then stored underground in geological reservoirs.
Enhanced weathering artificially stimulates the natural process of rock decomposition to increase the natural absorption of CO2 by mineral rocks (carbonate, silicate). Crushed rocks are spread on fields, the increased surface area speeds up the natural weathering process). The reaction stores the CO2 in mineral form.
Ocean alkalinisation consists of spreading mineral rocks (carbonate, silicate) in the ocean, which naturally absorb and store CO2 in mineral form via weathering processes.
Ocean fertilisation consists of adding otherwise limited nutrients (iron or nitrogen) to upper ocean waters in order to increase biological production. The availability of nutrients stimulates phytoplankton growth, therefore increasing CO2 sequestration. As they die, plankton sink to the deep ocean and permanently sequester the CO2.
Peatland restoration consists of restoring and re-wetting peatland ecosystems. These ecosystems capture and store CO2 in living biomass, which are then accumulated over a long period of time in stable or slowly decomposing peat layers.
Soil carbon sequestration refers to the increase in soil organic carbon content that occurs from land management changes such as modern farming methods, grassland restoration and creation of wetlands. The additional CO2 sequestered remains in the soil if adequately managed.