Saline Aquifer Storage Capacity Calculator
Saline formations -- deep underground rock layers saturated with brine too salty to drink -- are by far the largest potential CO2 storage resource, and estimating how much CO2 a given formation can hold is the first screening step for any geologic storage project. This calculator applies the standard DOE/NETL volumetric storage resource methodology: it converts reservoir area and net thickness into a bulk rock volume, applies porosity to get the pore space available, then applies a storage efficiency factor and CO2 density at reservoir conditions to convert that pore volume into a mass-based storage capacity in metric tons. It pairs naturally with our CO2 Storage/Sequestration Cost Calculator for the per-ton cost of injecting into a formation like this, and our CO2 Transport Cost Calculator for the cost of getting captured CO2 to the storage site.
The areal footprint of the saline formation being evaluated for CO2 storage.
The net thickness of porous, permeable rock actually available for CO2 storage within the formation -- not the full geologic formation thickness, which may include non-porous layers.
Typical saline sandstone reservoirs commonly have 15-30% porosity, representing the fraction of rock volume that is pore space capable of holding fluid.
DOE/NETL methodology typically uses a storage efficiency factor of roughly 0.5-5% for saline formations, reflecting that only a fraction of total pore volume can practically be filled with CO2 due to buoyancy, pressure limits, and incomplete sweep of the formation.
CO2 becomes a dense, supercritical fluid at typical storage depths below about 800 meters (2,600 feet), with density commonly estimated around 600-800 kg/m3 depending on exact pressure and temperature conditions.
reservoir area (acres) × 4,046.86 × net reservoir thickness (ft) × 0.3048
bulk reservoir volume (m3) × (porosity (%) ÷ 100)
(pore volume (m3) × (storage efficiency factor (%) ÷ 100) × CO2 density (kg/m3)) ÷ 1,000
This is a simplified planning-level volumetric estimate using the general DOE/NETL methodology framework. Actual storage capacity determination for a real project requires detailed geologic characterization, seismic surveys, and exploratory well data -- consult a qualified geologist or reservoir engineer for site-specific storage capacity assessment.
Results update live as you type. For planning and field-check estimates — always verify against applicable standards and equipment ratings.
How we calculate this →Storage efficiency factor is the single biggest lever in this calculation, and it's also the most conservative assumption by design -- even though the pore space in this example formation could theoretically hold far more, only about 2% of that pore volume is assumed practically usable for CO2 storage, due to buoyancy effects, pressure constraints, and the fact that injected CO2 never perfectly sweeps an entire formation. That conservative assumption still yields over 3.4 million metric tons of storage capacity in this example -- illustrating why large saline formations, even with cautious efficiency assumptions, can represent genuinely enormous CO2 storage resources.
How saline aquifer CO2 storage capacity is calculated
This calculator estimates the CO2 storage capacity of a saline aquifer formation in metric tons using the standard DOE/NETL volumetric storage resource methodology, which converts the physical dimensions and properties of a formation into a mass-based storage estimate through three sequential steps.
Bulk Reservoir Volume (m3) = Reservoir Area (acres) × 4,046.86 × Net Reservoir Thickness (ft) × 0.3048. Reservoir area in acres is converted to square meters by multiplying by 4,046.86 (the number of square meters in one acre), and net reservoir thickness in feet is converted to meters by multiplying by 0.3048; multiplying the resulting footprint area by the thickness gives the bulk rock volume of the porous, permeable portion of the formation. At the defaults (10,000 acres and 100 ft), that is 10,000 × 4,046.86 × 100 × 0.3048 = 1,233,085,128 m3.
Pore Volume (m3) = Bulk Reservoir Volume (m3) × (Porosity (%) ÷ 100). Porosity is the fraction of the bulk rock volume that is pore space capable of holding fluid, so multiplying the bulk volume by the porosity fraction gives the total connected pore volume available. At the defaults (1,233,085,128 m3 and 20% porosity), that is 1,233,085,128 × 0.20 = 246,617,026 m3.
CO2 Storage Capacity (metric tons) = (Pore Volume (m3) × (Storage Efficiency Factor (%) ÷ 100) × CO2 Density at Reservoir Conditions (kg/m3)) ÷ 1,000. Not all pore space can practically be filled with CO2, so the storage efficiency factor reduces the pore volume to the realistically usable fraction; multiplying by CO2 density converts that usable pore volume from a volume into a mass of CO2 (in kg), and dividing by 1,000 converts kilograms to metric tons. At the defaults (246,617,026 m3, 2% efficiency, and 700 kg/m3), that is (246,617,026 × 0.02 × 700) ÷ 1,000 = 3,452,638 metric tons.
Two notes on the model. First, the storage efficiency factor is the single most consequential and most uncertain input -- DOE/NETL methodology typically uses a range of roughly 0.5-5% for saline formations, reflecting that only a fraction of total pore volume can practically be filled with CO2 due to buoyancy effects (injected CO2 is buoyant relative to the brine it displaces and migrates toward the top of the formation), pressure constraints (injection is limited to avoid fracturing the cap rock), and incomplete sweep of the formation, so the editable field lets you substitute a formation-specific figure. Second, this calculator uses the general framework of the DOE/NETL volumetric method, which is appropriate for early-stage, planning-level screening; a full storage resource assessment for an actual project requires detailed subsurface data from seismic surveys and exploratory wells, dynamic reservoir simulation, and pressure/injectivity analysis that a simplified volumetric calculation cannot capture, so consult a qualified geologist or reservoir engineer for site-specific assessment. For the per-ton cost of injecting CO2 into a formation like this, see the CO2 Storage/Sequestration Cost Calculator; for the cost of transporting captured CO2 to the storage site, see the CO2 Transport Cost Calculator. Data sources: DOE/NETL volumetric CO2 storage resource methodology and storage efficiency factor ranges from U.S. Department of Energy National Energy Technology Laboratory (NETL) saline formation storage capacity assessment methodologies; porosity ranges for saline sandstone reservoirs from DOE and USGS geologic characterization studies; supercritical CO2 density ranges at storage-depth conditions from IPCC and NETL technical reports. Verification: with defaults (10,000 acres, 100 ft, 20% porosity, 2% efficiency, 700 kg/m3), Bulk Reservoir Volume = 1,233,085,128 m3, Pore Volume = 246,617,026 m3, CO2 Storage Capacity = 3,452,638 metric tons.