Free Online CO2 Storage Capacity Calculator: Saline Aquifer Screening

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The volumetric screening formula: pore volume times CO2 density times a storage efficiency factor. Saline aquifer efficiency typically runs 1 to 4 percent of pore volume. Below about 800 m, CO2 is supercritical and dense enough to store efficiently; the tool warns if your depth is shallower.

How much CO2 a formation can hold

Carbon capture and storage lives or dies on a simple question: is there enough pore space, deep enough, to matter? The tool above answers it with the standard volumetric screening formula used by every storage atlas: area times net thickness times porosity gives pore volume, CO2 density at depth converts volume to mass, and a storage efficiency factor admits that only a small fraction of the pore space ever fills. The result comes out in megatonnes, alongside the project life at one megatonne per year and an emissions equivalence that makes the number legible.

Cross section of a CO2 storage site with an injector well placing a supercritical CO2 plume in a saline aquifer beneath a caprock seal, with the volumetric capacity formula alongside
Pore volume times CO2 density times an efficiency factor: the screening arithmetic that ranks storage sites.

This opens the CO2 Storage and Geothermal Suite in the bar above, the energy transition wing of the calculatgeek tool family.

The two numbers that carry the risk

  • Storage efficiency is the honest uncertainty: regional screening studies use 1 to 4 percent of pore volume for saline aquifers, and the difference between those bounds is a factor of four in capacity.
  • CO2 density depends on depth: below about 800 m the fluid is supercritical at 600 to 750 kg/m3, which is why the tool checks your depth and warns when a shallow site would store vapor instead.
  • Net thickness means reservoir that actually accepts CO2, after cutting shales and tight streaks, exactly like net pay in petroleum work.
  • Capacity is necessary but not sufficient: injectivity and seal integrity, covered by the plume tool in this suite, decide whether the capacity is usable.

What this tool is for

Ranking candidate formations, checking the arithmetic behind published storage atlases, and giving policy discussions a number instead of an adjective. Bankable capacity estimates add dynamic simulation and site-specific efficiency factors; every one of them starts from exactly this formula.

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