Pyrogenic carbon capture and storage (PyCCS) is a proposed

carbon sequestration Carbon sequestration is the process of storing carbon in a carbon pool. Carbon dioxide () is naturally captured from the atmosphere through biological, chemical, and physical processes. These changes can be accelerated through changes in lan ...

technology that can mitigate climate change while improving

soil fertility Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality.

. It is discussed as a promising technology for

greenhouse gas removal Carbon dioxide removal (CDR), also known as negative emissions, is a process in which carbon dioxide gas () is removed from the atmosphere and sequestered for long periods of time. Similarly, greenhouse gas removal (GGR) or negative greenh ...

.Constanze Werner et al. (2018): ''Biogeochemical potential of biomass pyrolysis systems for limiting global warming to 1.5° C.''

Environmental Research Letters ''Environmental Research Letters'' is a quarterly, peer-reviewed, open-access, scientific journal covering research on all aspects of environmental science. It is published by IOP Publishing. The editor-in-chief is Daniel Kammen (University of Cal ...

, 13(4), 044036.

Principle

The principle of PyCCS is that the

biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bio ...

(e.g. trees) removes CO₂ from the atmosphere during its growth via photosynthesis. This biomass is then harvested and pyrolyzed (see below), with a portion of the carbon dioxide bound in the biomass being captured in the ground, after being reduced to carbon and viscous compounds (

charcoal Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, ...

). The flammable gas mixture, which is the lightest fraction in pyrolysis, is collected and used as fuel; the carbon dioxide produced when combusting it is captured traditionally.

Technology

Pyrolysis in the context of carbon capture and storage has been described by Werner et al. (2018) as "the thermal treatment of biomass at 350 °C–900 °C in an oxygen-deficient atmosphere. Three main carbonaceous products are generated during this process, which can be stored subsequently in different ways to produce egative emissions a solid biochar as soil amendment, a pyrolytic liquid (bio-oil) pumped into depleted fossil oil repositories, and permanent-pyrogas (dominated by the combustible gases CO, H₂ and CH₄) that may be transferred as CO₂ to geological storages after combustion." In low-oxygen conditions, the thermal-chemical conversion of organic materials (including

) produces both volatiles, termed pyrolytic gases (pyrogases), as well as solid carbonaceous co-products, termed biochar. While the pyrogases mostly condense into liquid

bio-oil Pyrolysis oil, sometimes also known as bio-crude or bio-oil, is a synthetic fuel under investigation as substitute for petroleum. It is obtained by heating dried biomass without oxygen in a reactor at a temperature of about with subsequent co ...

, which may be used as an energy source, biochar has been proposed as a tool for sequestering carbon in soil. Once mixed into soil, biochar, which is less susceptible to remineralization into CO₂ and CH₄ than non-pyrogenic biomass, fragments into micro- and nano-particles which can be transported to deeper soil horizons, groundwater, or other compartments that further protect it from degradation. Multiple studies have demonstrated that pyrogenic carbon is stable over centennial timescales.

References

{{Reflist, 2 Carbon dioxide removal