Abstract: A method of producing a gaseous product, for instance gaseous oxygen in accordance with a cyclical demand pattern having high and low periods of demand. During periods of high demand, liquid is vaporized against condensing air which is in turn stored. During low demand periods, product is accumulated and previously stored liquid air is introduced into the column. During both high and low periods of demand liquid product is drawn to reduce the percentage variance in the required flow rate to the booster compressor used in producing the air to be liquefied. Preferably, during periods of high demand, a turbine used in generating refrigeration can be turned down to increase the amount of air available for condensation and with a reduction in production of liquid product.