CO Capture and Storage - Energy and Climate: How to Achieve a Successful Energy Transition - page 112

contain resources of interest, so it has hardly been studied. A major
characterisation effort is required in order to qualify this type of aquifer
for geological storage.

Storage in unexploited coal seams

.

Storage in unexploited coal seams is based upon the capacity of coal to
adsorb CO 2 preferentially instead of the methane initially present. This
trapping mechanism also enables the recovery of methane, which can be
recovered in producing wells, and is a potentially attractive economic
benefit. The main difficulty associatedwith this storage solution is the low
permeability of this type of formation. As a result, it is not possible to
inject large quantities of CO 2 without multiplying the number of injecting
wells. Such a solution is limited to unexploited coal seams in order to avoid
any leakage of CO 2 through mining galleries.
Table 8.1 shows the potential CO 2 storage capacity for different
geological structures (IEA data). Although current estimates are hardly
precise, it appears that the potential storage capacity might be adequate
for dealing with the overall world CO 2 emissions.

Table 8.1 Potential storage capacity for different storage modes

Storage options Total capacity

Gt CO 2 Share of aggregate

emissions in 2050 (%)

Depleted oil and gas
reservoirs

920 45

Deep aquifers 400-10 000 20-500

Unexploited coal seams 40 2

A more precise evaluation of storage capacities worldwide is needed in
order to assess better the overall potential CO 2 storage capacity.

Industrial applications of CO 2 capture and storage

Carbon dioxide capture and storage (CCS) can be applied to all industrial
installations emitting large amounts of CO 2 .