Share of CCS in cumulative CO2 omissions reductions 20002100

Figure 8.5 Relationship between (1) the imputed share of CCS in total cumulative emissions reductions in per cent and (2) total cumulative CCS deployment in GtCO2 (2000-2100). The scatter plots depict values for individual TAR mitigation scenarios for the six SRES scenario groups. The vertical dashed lines show the average share of CCS in total emissions mitigation across the 450 to 750 ppmv stabilization scenarios, and the dashed horizontal lines illustrate the scenarios' average cumulative storage requirements across 450 to 750 ppmv stabilization.

at the stabilization of CO2 concentrations at 750 ppmv to 54% for 450 ppmv scenarios.13 However, the full uncertainty range of the set of TAR mitigation scenarios includes extremes on both the high and low sides, ranging from scenarios with zero CCS contributions to scenarios with CCS shares of more than 90% in total emissions abatement.

8.3.3.1 Cumulative CCS deployment

Top-down and bottom-up energy-economic models have been used to examine the likely total deployment of CCS technologies (expressed in GtC). These analyses reflect the fact that the future usage of CCS technologies is associated with large uncertainties. As illustrated by the IPCC-TAR mitigation scenarios, global cumulative CCS during the 21st century could range - depending on the future characteristics of the reference world (i.e., baselines) and the employed stabilization target

(450 to 750 ppmv) - from zero to more than 5500 GtCO2 (1500 GtC) (see Figure 8.6). The average cumulative CO2 storage (2000-2100) across the six scenario groups shown in Figure 8.6 ranges from 380 GtCO2 (103 GtC) in the 750 ppmv stabilization scenarios to 2160 GtCO2 (590 GtC) in the 450 ppmv scenarios (Table 8.5).14 However, it is important to note that the majority of the six individual TAR scenarios (from the 20th to the 80th percentile) tend to cluster in the range of 220-2200 GtCO2 (60600 GtC) for the four stabilization targets (450-750 ppmv).

The deployment of CCS in the TAR mitigation scenarios is comparable to results from similar scenario studies projecting storage of 576-1370 GtCO2 (157-374 GtC) for stabilization scenarios that span 450 to 750 ppmv (Edmonds et al., 2000) and storage of 370 to 1250 GtCO2 (100 to 340 GtC) for stabilization scenarios that span 450 to 650 ppmv (Dooley and Wise, 2003). Riahi et al. (2003) project 330-890 GtCO2 (90-243 GtC) of stored CO2 over the course of the current century for various

13 The range for CCS mitigation in the TAR mitigation scenarios is calculated on the basis of the cumulative emissions reductions from 1990 to 2100, and represents the average contribution for 450 and 750 ppmv scenarios across alternative modelling frameworks and SRES baseline scenarios. The full range across all scenarios for 450 ppmv is 20 to 95% and 0 to 68% for 750 ppmv scenarios respectively.

14 Note that Table 8.5 and Figure 8.6 show average values of CCS across alternative modelling frameworks used for the development of the TAR mitigation scenarios. The deployment of CCS over time, as well as cumulative CO2 storage in individual TAR mitigation scenarios, are illustrated in Figures 8.5 and 8.7.

Figure 8.6 Global cumulative CO2 storage (2000-2100) in the IPCC TAR mitigation scenarios for the six SRES scenario groups and CO2 stabilization levels between 450 and 750 ppmv. Values refer to averages across scenario results from different modelling teams. The contribution of CCS increases with the stringency of the stabilization target and differs considerably across the SRES scenario groups.

Figure 8.6 Global cumulative CO2 storage (2000-2100) in the IPCC TAR mitigation scenarios for the six SRES scenario groups and CO2 stabilization levels between 450 and 750 ppmv. Values refer to averages across scenario results from different modelling teams. The contribution of CCS increases with the stringency of the stabilization target and differs considerably across the SRES scenario groups.

550 ppmv stabilization cases. Fujii and Yamaji (1998) have also included ocean storage as an option. They calculate that, for a stabilization level of 550 ppmv, 920 GtCO2 (250 GtC) of the emissions reductions could be provided by the use of CCS technologies and that approximately one-third of this could be stored in the ocean. This demand for CO2 storage appears to be within global estimates of total CO2 storage capacity presented in Chapters 5 and 6.

8.3.3.2 Timing and deployment rate

Recently, two detailed studies of the cost of CO2 transport and storage costs have been completed for North America (Dooley et al, 2004a) and Western Europe (Wildenborg et al, 2004). These studies concur about the large potential of CO2 storage capacity in both regions. Well over 80% of the emissions from current CO2 point sources could be transported and stored in candidate geologic formations for less than 12-15 US$/tCO2 in North America and 25 US$/tCO2 in Western Europe. These studies are the first to define at a continental scale a 'CO2 storage supply curve', conducting a spatially detailed analysis in order to explore the relationship between the price of CO2

transport and storage and the cumulative amount of CO2 stored. Both studies conclude that, at least for these two regions, the CO2 storage supply curves are dominated by a very large single plateau (hundreds to thousands of gigatonnes of CO2), implying roughly constant costs for a wide range of storage capacity15. In other words, at a practical level, the cost of CO2 transport and storage in these regions will have a cap. These studies and a handful of others (see, for example, IEA GHG, 2002) have also shown that early (i.e., low cost) opportunities for CO2 capture and storage hinge upon a number of factors: an inexpensive (e.g., high-purity) source of CO2; a (potentially) active area of advanced hydrocarbon recovery (either EOR or ECBM); and the relatively close proximity of the CO2 point source to the candidate storage reservoir in order to minimize transportation costs. These bottom-up studies provide some of the most detailed insights into the graded CCS resources presently available, showing that the set of CCS opportunities likely to be encountered in the real world will be very heterogeneous. These

Table 8.5 Cumulative CO2 storage (2000 to 2100) in the IPCC TAR mitigation scenarios in GtCO2. CCS contributions for the world and for the four SRES regions are shown for four alternative stabilization targets (450, 550, 650, and 750 ppmv) and six SRES scenario groups. Values refer to averages across scenario results from different modelling teams.

Table 8.5 Cumulative CO2 storage (2000 to 2100) in the IPCC TAR mitigation scenarios in GtCO2. CCS contributions for the world and for the four SRES regions are shown for four alternative stabilization targets (450, 550, 650, and 750 ppmv) and six SRES scenario groups. Values refer to averages across scenario results from different modelling teams.

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