The Carbfix consortium has developed methods to capture CO2 from concentrated sources and ambient air and subsequent storage as minerals in basaltic rocks. Mineralisation is the safest way of storing carbon. Before injection via the Carbfix method, CO2 gas is dissolved in water. In the subsurface reservoir, the acidic CO2-charged water releases Ca, Mg and Fe from the basalt, that can combine with the CO2 to form stable carbonate minerals. In the talk we will define the temperature and pressure window for this storage method, which will affect the design of the injection equipment and thus the storage cost. For freshwater applications, the Carbfix method has been tested and applied from 20°C to 270°C. The upper temperature limit is defined by the reaction transforming Ca-carbonates and quartz to wollastonite. Low temperatures, 4°-20°C, slow down the rate of gas-water and water-rock interactions and have not yet been tested in the field. Bacteria activity could affect these processes at 4°-121°C. Seawater contains Ca and SO4, and when injected in areas with a high geothermal gradient, the temperature of injected seawater could rise past 150°C, resulting in anhydrite precipitation within the injection well, which could clog the well over time. Hence, the temperature window for CO2-charged seawater injections is narrower than that for freshwater, around 20°-150°. The pressure window is defined by the injection method and solubility of CO2 in water and seawater. If CO2 is dissolved at low pressure (e.g. 6 bar) in a scrubber on the surface, theoretical depth of a high injectivity well does not need to be deeper than 100 -200 m. If CO2 is dissolved within the injection well, the preferred gas pressure is around 25 bar at 25°C. This requires a minimum of 250 m water column above to point of gas release in the well, and a similar downhole distance of about 250 m for the kinetic driven dissolution of the down-going gas bubbles. Thus, the depth of the injection well has to be > 500 m. Once the gas bubbles are dissolved in the injection water, it is denser than the formation water, and has the tendency to sink. If the transmissivity of the well is good, there is no need to pressurize the injected water.