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

==== 6.7.1.3 Technology Options to Offset Residual Emissions ====

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CDR technologies can offset emissions from sectors that are difficult to decarbonise ( [[#6.6|Section 6.6]] ), altering the timeline and character of energy sector transitions. A number of studies suggest that CDR is no longer a choice, but rather a necessity to limit warming to 1.5°C ( [[#Rogelj--2015a|Rogelj et al. 2015a]] ; [[#Detz--2018|Detz et al. 2018]] ; [[#Luderer--2018|Luderer et al. 2018]] ; [[#Strefler--2018|Strefler et al. 2018]] ; [[#van%20Vuuren--2018|van Vuuren et al. 2018]] ). The reliance on CDR varies across scenarios and is tightly linked to future energy demand and the rate of emission reductions in the next two decades: deeper near-term emissions reductions will reduce the need to rely on CDR to constrain cumulative CO 2 emissions. Some studies have argued that only with a transition to lower energy demands will it be possible to largely eliminate the need for engineered CDR options ( [[#Grubler--2018|Grubler et al. 2018]] ; [[#van%20Vuuren--2018|van Vuuren et al. 2018]] ). Overall, the amount of CDR will depend on CO 2 capture costs, lifestyle changes, reduction in non-CO 2 GHGs, and utilisation of zero-emission end-use fuels (Muratori et al. 2017; [[#van%20Vuuren--2018|van Vuuren et al. 2018]] ).

There is substantial uncertainty about the amount of CDR that might ultimately be deployed. In most scenarios that limit warming to 1.5°C, CDR deployment is fairly limited through 2030 at less than 1 GtCO 2 yr –1 . The key projected increase in CDR deployment (BECCS and DAC only) occurs between 2030 and 2050, with annual CDR in 2050 projected at 2.5–7.5 GtCO 2 yr –1 in 2050 (interquartile range) in scenarios limiting warming to 1.5°C (&gt;50%) with limited or no overshoot, and 0.7–1.4 GtCO 2 yr –1 in 2050 in scenarios limiting warming to 2°C (&gt;67%) with action starting in 2020. This characteristic of scenarios largely reflects substantial capacity addition of BECCS power plants. BECCS is also deployed in multiple ways across sectors. For instance, the contribution (interquartile range) of BECCS to electricity is 1–5% in 2050 in scenarios limiting warming to 1.5°C (&gt;50%) with no or limited overshoot, and 0–5% in scenarios that limit warming to 2°C (&gt;67%) with action starting in 2020. The contribution (interquartile range) of BECCS to liquid fuels is 9–21% in 2050 in scenarios limiting warming to 1.5°C (&gt;50%) with no or limited overshoot and 2–11% in scenarios that limit warming to 2°C (&gt;67%) with action starting in 2020. Large-scale deployment of CDR allows flexibility in timing of emissions reduction in hard-to-decarbonise sectors.

CDR will influence the potential fossil-related stranded assets (Box 6.13). Availability of low-cost CDR can help reduce premature retirement for some fossil fuel infrastructure. CDR can allow countries to reach net-zero emissions without phasing out all fossil fuels. Specific infrastructure could also be extended if it is used to burn biomass or other non-emitting sources. For example, existing coal-fired power plants, particularly those with CCS, could be co-fired with biomass ( [[#Woolf--2016|Woolf et al. 2016]] ; [[#Lu--2019|Lu et al. 2019]] ; [[#Pradhan--2021|Pradhan et al. 2021]] ). In many scenarios, energy sector CDR is deployed to such an extent that energy sector CO 2 emissions become negative in the second half of the century (Chapter 3).

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