Sinking CO<sub>2</sub> in Supercritical Reservoirs
Francesco Parisio, Víctor Vilarrasa
Abstract
Abstract Geologic carbon storage is required for achieving negative CO 2 emissions to deal with the climate crisis. The classical concept of CO 2 storage consists in injecting CO 2 in geological formations at depths greater than 800 m, where CO 2 becomes a dense fluid, minimizing storage volume. Yet CO 2 has a density lower than the resident brine and tends to float, challenging the widespread deployment of geologic carbon storage. Here, we propose for the first time to store CO 2 in supercritical reservoirs to reduce the buoyancy‐driven leakage risk. Supercritical reservoirs are found at drilling‐reachable depth in volcanic areas, where high pressure ( p > 21.8 MPa) and temperature ( T > 374°C) imply CO 2 is denser than water. We estimate that a CO 2 storage capacity in the range of 50–500 Mt yr −1 could be achieved for every 100 injection wells. Carbon storage in supercritical reservoirs is an appealing alternative to the traditional approach.