Editing IPCC:AR6/WGIII/Chapter-6 (section)

==== 6.6.2.7 Carbon Dioxide Removal ====

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While CDR is likely necessary for net-zero energy systems, the scale and mix of strategies is unclear –nonetheless some combination of BECCS and DACCS are likely to be part of net-zero energy systems ( ''high confidence'' ). Studies indicate that energy-sector CDR may potentially remove 5–12 GtCO 2 annually globally in net-zero energy systems ( [[#Fuss--2018|Fuss et al. 2018]] ) (Figure 6.22; [[#6.7|Section 6.7]] ; Chapter 12). CDR is not intended as a replacement for emissions reduction, but rather as a complementary effort to offset residual emissions from sectors that are not decarbonised and from other low-carbon technologies such as fossil CCS ( [[#McLaren--2019|McLaren et al. 2019]] ; [[#Gaffney--2020|Gaffney et al. 2020]] ; [[#Iyer--2021|Iyer et al. 2021]] ).

CDR covers a broad set of methods and implementation options (Chapters 7 and 12). The two CDR methods most relevant to the energy sector are BECCS, which is used to produce energy carriers, and DACCS which is an energy user ( [[#Smith--2016|Smith et al. 2016]] ; [[#Singh--2021|Singh and Colosi 2021]] ). BECCS has value as an electricity generation technology, providing firm, dispatchable power to support electricity grids with large amounts of VRE sources, and reducing the reliance on other means to manage these grids, including electricity storage ( [[#Mac%20Dowell--2017|Mac Dowell et al. 2017]] ; [[#Bistline--2021a|Bistline and Blanford 2021a]] ). BECCS may also be used to produce liquid fuels or gaseous fuels, including hydrogen ( [[#6.4.2.6|Section 6.4.2.6]] ) ( [[#Muratori--2020b|Muratori et al. 2020b]] ). For instance, CO 2 from bio-refineries could be captured at &lt;USD45 tCO 2 –1 ( [[#Sanchez--2018|Sanchez et al. 2018]] ). Similarly, while CO 2 capture is expensive in the electricity sector, its integration with hydrogen via biomass gasification can be achieved at an incremental capital cost of 3–35% ( [[#Muratori--2020b|Muratori et al. 2020b]] ) ( [[#6.4|Section 6.4]] ). As with all uses of bioenergy, linkages to broad sustainability concerns may limit the viable development, as will the presence of high-quality geologic sinks in close proximity ( [[#Melara--2020|Melara et al. 2020]] ).

DACCS offers a modular approach to CDR ( [[#Creutzig--2019|Creutzig et al. 2019]] ), but it could be a significant consumer of energy. DAC could also interact with other elements of the energy systems as the captured CO 2 could be reused to produce low-carbon methanol and other fuels ( [[#Hoppe--2018|Hoppe et al. 2018]] ; [[#Realmonte--2019|Realmonte et al. 2019]] ; [[#Zhang--2020|Zhang and Fujimori 2020]] ). DACCS might also offer an alternative for use of excess electricity produced by variable renewables ( [[#Wohland--2018|Wohland et al. 2018]] ), though there are uncertainties about the economic performance of this integrated approach.

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