Large-Scale Geological Carbon Sequestration - Introduction to Carbon Capture and Sequestration - page 483

relatively large effort has gone into capacity assessment, one must treat
these estimates with caution; as with many calculations involving the
subsurface there is great uncertainty in the numbers.

Pyramid representations

Despite this large uncertainty inherent in large-scale prediction of capac-
ity, more accurate assessments can be made on smaller scales when
more site-specifi c information is available. By confi ning the assessment
to that subset of the region where storage is economical and conforms
to regulations and requirements, the derived capacity is naturally
smaller. These simple concepts are illustrated in Figure 10.3.4 by a
pyramid in which the large base represents both large uncertainty and
large storage volume associated with large-scale capacity assessment.
At the top of the pyramid, we have a particular site where characteriza-
tion data have been collected and evaluated. As smaller regions are
examined in more detail, both the uncertainty and the storage volume
estimates decrease.
In summary, the assessment of CO 2 storage capacity is an uncertain
endeavor, but broad agreement exists within the geological carbon
sequestration community that the large sedimentary basins of the world
contain enormous capacity for future CO 2 storage [10.35].

(a) (b)

Figure 10.3.3 DOE method to estimate storage volume
The DOE methodology (a) considers the entire formation thickness as storage volume,
e.g., by residual-phase trapping, whereas the CSLF methodology (b) considers only the
structural traps as storage volume. Figure adapted from Causebrook [10.32] .