Terrestrial Saline Aquifer Sequestration

Terrestrial saline aquifers are saline aquifers located on land; they are often made up of sedimentary rock and may be covered by a layer of relatively impermeable rock, called the caprock. Because the CO2 is less dense than the brine in terrestrial injection, some CO2 will rise up and become trapped by the cap-rock above. In addition, some CO2 will interact with minerals within the aquifer and become trapped. 

Injection of CO2 should be confined to depths of 500 m, the shallowest depth at which CO2 is super-critical, to 3000m, the depth below which effective storage decreases and price per unit of CO2 injected increases (Eccles et al, 2009). Efficiency of CO2 storage increases with density; density generally increases with depth, but temperatures rise as depth increases and pore space decreases as the rock becomes more compacted, resulting in decreased storage efficiency past certain depths (Intergovernmental Panel on Climate Change, 2008).

There are few national regulations specifically dealing with CO2 storage, but regulations dealing with oil and gas, groundwater, and the underground injection of fluids can, in many cases, be readily adapted and/or adopted.  Policy makers must still determine the classification of CO2 (as a waste, pollutant, or otherwise), different levels of jurisdiction (international, national, subnational), and the ownership of pore space (Intergovernmental Panel on Climate Change, 2008; Bachu, 2007).



Potential Storage Sites

Capacity Estimates:

Estimates of CO2 storage potentials in deep saline aquifers (including offshore) (IEA, 2008):

  (Gt CO2)
Alberta (Canada) 1000 - 4000
USA 900 - 3400
Europe 30 - 577
Worldwide 2000 - 20,000

(Bradshaw et al, 2007) (Bradshaw et al, 2007)

(Sharma et al, 2009)(Sharma et al, 2009)

Cost Estimates:

In 2005, the IPCC gave the following estimates for storage costs in saline aquifers, though prices have likely increased since then (IEA, 2008):

Location cost ($ per tonne CO2)
USA onshore 0.40 - 4.50
Europe onshore 1.90 - 6.20
Europe/North Sea 4.70 - 12
Australia onshore 0.20 - 5.10
Australia offshore 0.50 - 30

(Eccles et al, 2009) ( (Eccles et al, 2009) ("ton" refers to metric tonnes)