the periodic use pattern of the customer is to size the amine plant to meet the peak consumption rate of the customer and to vent the co 2 rich product stream during off times i e when co 2 is not required the method described above for producing gaseous product stream 9 is performed only during on times however this approach results in capital and operating costs that can be lowered still further with the alternative embodiment described hereinbelow this embodiment uses intermediate storage to help cope with the periodic use pattern of the customer while significantly reducing the cost penalty referring to fig3 the reference numerals that are common to fig3 and 1 indicate the same streams and components that they indicate in fig1 in fig3 gaseous purified stream 6 is conveyed to point 20 which can be a controllable valve or equivalent unit at point 20 stream 6 can be split into streams 11 and 12 stream 12 feeds into storage vessel 13 stream 14 emerges from vessel 13 and feeds into stream 11 to form stream 15 stream 8 feeds into stream 15 to form stream 9 fig3 represents an embodiment in which the gaseous purified stream from processor 5 can be stored in times when there is no need or when there is only a reduced need compared to the average need over time to produce a gaseous product stream 9 during those off times all or a portion of the purified gaseous stream is diverted into vessel 13 where the carbon dioxide can be.