Based on the models derived for the enrichment of mine ventilation air in methane via pressure swing adsorption (PSA) or, alternatively, membrane separation, total annual costs are analysed for a wide range of the operating parameters. For a twofold increase in CH4 concentration the cost of the membrane separation is by several percent higher than that of the PSA process. Also, the profit is assessed due to an increased heat production in a catalytic flow reversal reactor (CFRR).