A firefighting apparatus includes a reaction chamber, a CO2 tank fluidly connected to the reaction chamber, acid and carbonate tanks, acid and carbonate pumps, and a controller. The acid and carbonate pumps act to correspondingly regulate flow of acid from the acid tank and carbonate from the carbonate tank to the reaction chamber. Acid and carbonate react within the reaction chamber to produce CO2 gas which flows into the CO2 tank and liquid byproduct which is releasable through a reaction chamber outlet. A CO2 gas delivery valve is fluidly connected to a delivery outlet of the CO2 tank to regulate release of CO2 therefrom. The CO2 tank includes a pressure sensor for measuring a CO2 tank pressure. The controller is configured to control operation of the acid and carbonate pumps, and the CO2 gas delivery valve according to a user command signal, the CO2 tank pressure, or both.