Editing IPCC:AR6/SR15/Chapter-2 (section)

==== 2.4.2.3 Deployment of carbon capture and storage ====

<div id="section-2-4-2-3-block-1"></div>

Studies have shown the importance of CCS for deep mitigation pathways (Krey et al., 2014a; Kriegler et al., 2014b) <sup>[[#fn:r377|377]]</sup> , based on its multiple roles to limit fossil-fuel emissions in electricity generation, liquids production, and industry applications along with the projected ability to remove CO <sub>2</sub> from the atmosphere when combined with bioenergy. This remains a valid finding for those 1.5°C and 2°C pathways that do not radically reduce energy demand or do not offer carbon-neutral alternatives to liquids and gases that do not rely on bioenergy.

There is a wide range of CCS that is deployed across 1.5°C pathways (Figure 2.17). A few 1.5°C pathways with very low energy demand do not include CCS at all (Grubler et al., 2018) <sup>[[#fn:r378|378]]</sup> . For example, the ''LED'' pathway has no CCS, whereas other pathways, such as the S5 pathway, rely on a large amount of BECCS to get to net-zero carbon emissions. The cumulative fossil and biomass CO <sub>2</sub> stored through 2050 ranges from zero to 300 GtCO <sub>2</sub> across 1.5°C pathways with no or limited overshoot, with zero up to 140 GtCO <sub>2</sub> from biomass captured and stored. Some pathways have very low fossil-fuel use overall, and consequently little CCS applied to fossil fuels. In 1.5°C pathways where the 2050 coal use remains above 20 EJ yr <sup>−1</sup> in 2050, 33–100% is combined with CCS. While deployment of CCS for natural gas and coal vary widely across pathways, there is greater natural gas primary energy connected to CCS than coal primary energy connected to CCS in many pathways (Figure 2.17).

CCS combined with fossil-fuel use remains limited in some 1.5°C pathways (Rogelj et al., 2018) <sup>[[#fn:r379|379]]</sup> , as the limited 1.5°C carbon budget penalizes CCS if it is assumed to have incomplete capture rates or if fossil fuels are assumed to continue to have significant lifecycle GHG emissions (Pehl et al., 2017) <sup>[[#fn:r380|380]]</sup> . However, high capture rates are technically achievable now at higher cost, although efforts to date have focussed on reducing the costs of capture (IEAGHG, 2006; NETL, 2013) <sup>[[#fn:r381|381]]</sup> .

The quantity of CO <sub>2</sub> stored via CCS over this century in 1.5°C pathways with no or limited overshoot ranges from zero to more than 1,200 GtCO <sub>2</sub> , (Figure 2.17). The IPCC Special Report on Carbon Dioxide Capture and Storage (IPCC, 2005) <sup>[[#fn:r382|382]]</sup> found that that, worldwide, it is ''likely'' that there is a technical potential of at least about 2,000 GtCO <sub>2</sub> of storage capacity in geological formations. Furthermore, the IPCC (2005) <sup>[[#fn:r383|383]]</sup> recognized that there could be a much larger potential for geological storage in saline formations, but the upper limit estimates are uncertain due to lack of information and an agreed methodology. Since IPCC (2005) <sup>[[#fn:r384|384]]</sup> , understanding has improved and there have been detailed regional surveys of storage capacity (Vangkilde-Pedersen et al., 2009; Ogawa et al., 2011; Wei et al., 2013; Bentham et al., 2014; Riis and Halland, 2014; Warwick et al., 2014; NETL, 2015) <sup>[[#fn:r385|385]]</sup> and improvement and standardization of methodologies (e.g., Bachu et al. 2007a, b) <sup>[[#fn:r386|386]]</sup> . Dooley (2013) <sup>[[#fn:r387|387]]</sup> synthesized published literature on both the global geological storage resource as well as the potential demand for geologic storage in mitigation pathways, and found that the cumulative demand for CO <sub>2</sub> storage was small compared to a practical storage capacity estimate (as defined by Bachu et al., 2007a) <sup>[[#fn:r388|388]]</sup> of 3,900 GtCO <sub>2</sub> worldwide. Differences remain, however, in estimates of storage capacity due to, for example, the potential storage limitations of subsurface pressure build-up (Szulczewski et al., 2014) <sup>[[#fn:r389|389]]</sup> and assumptions on practices that could manage such issues (Bachu, 2015) <sup>[[#fn:r390|390]]</sup> . Kearns et al. (2017) <sup>[[#fn:r391|391]]</sup> constructed estimates of global storage capacity of 8,000 to 55,000 GtCO <sub>2</sub> (accounting for differences in detailed regional and local estimates), which is sufficient at a global level for this century, but found that at a regional level, robust demand for CO <sub>2</sub> storage exceeds their lower estimate of regional storage available for some regions. However, storage capacity is not solely determined by the geological setting, and Bachu (2015) <sup>[[#fn:r392|392]]</sup> describes storage engineering practices that could further extend storage capacity estimates. In summary, the storage capacity of all of these global estimates is larger than the cumulative CO <sub>2</sub> stored via CCS in 1.5°C pathways over this century.

There is uncertainty in the future deployment of CCS given the limited pace of current deployment, the evolution of CCS technology that would be associated with deployment, and the current lack of incentives for large-scale implementation of CCS (Bruckner et al., 2014; Clarke et al., 2014; Riahi et al., 2017) <sup>[[#fn:r393|393]]</sup> . Given the importance of CCS in most mitigation pathways and its current slow pace of improvement, the large-scale deployment of CCS as an option depends on the further development of the technology in the near term. Chapter 4 discusses how progress on CCS might be accelerated.

<div id="section-2-4-2-3-block-2"></div>

<span id="figure-2.17"></span>
<!-- START IMG -->
<!-- IMG TITLE -->
'''Figure 2.17'''

<span id="section-10"></span>
<!-- IMG CAPTION -->
CCS deployment in 1.5°C and 2°C pathways for (a) biomass, (b) coal and (c) natural gas (EJ of primary energy) and (d) the cumulative quantity of fossil (including from, e.g., cement production) and biomass  CO <sub>2</sub>  stored via CCS (in GtCO <sub>2</sub>  stored).
<!-- IMG FILE -->
[[File:cb4d3c78abee4a1910e8f532033e509f Figure-2.17-1024x674.jpg]]

TBox plots show median, interquartile range and full range of pathways in each temperature class. Pathway temperature classes (Table 2.1), illustrative pathway archetypes, and the IEA’s Faster Transition Scenario (IEA WEM) (OECD/IEA and IRENA, 2017) are indicated in the legend.

Original Creation for this Report using IAMC 1.5°C Scenario Data hosted by IIASA

<!-- END IMG -->
<span id="energy-end-use-sectors"></span>