Abstract: Hydrogen is produced by electrolysis of water using electricity generated from a renewable energy source such as wind and/or solar radiation, compressed in a multistage compression system and consumed in at least one downstream process. Supply of hydrogen to the downstream process(es) fluctuates with demand and/or the availability of the renewable energy source. In order to accommodate such fluctuations, excess hydrogen is stored during periods when production of hydrogen exceeds that required by the downstream process(es) so that, during periods when demand exceeds production, hydrogen is removed from storage and, after suitable pressure reduction, fed to the downstream process(es) via a stage of the multistage compression system.

Abstract: According to an embodiment, a method of operating an oxy/fuel system and an oxy/fuel system circulate a support gas in the combustion system prior to activating at least one burner, produce the combustion fluid including CO2, wherein a level of the CO2 in the combustion fluid increases as a function of time, and continue production of the combustion fluid to exceed a predetermined level of the CO2 in the combustion fluid, for a period of time, the predetermined level being sufficient to permit the CO2 to be purified by a CO2 purification unit.

Abstract: SO2 and/or NOx are removed from gaseous CO2 at elevated pressure(s) in the presence of molecular oxygen and water and, when SO2 is to be removed, NOx, to convert SO2 to sulfuric acid and/or NOx to nitric acid. The sulfuric acid and/or nitric acid is/are then removed from the gaseous carbon dioxide to produce SO2-free, NOx-lean carbon dioxide gas. The invention has particular application in the removal of SO2 and/or NOx from carbon dioxide flue gas produced in an oxyfuel combustion process, for example, in a pulverized coal fired power station.