Unminable coalbeds are potentially large storage reservoirs for the sequestration of anthropogenic CO(2) and offer the benefit of enhanced methane production, which can offset some of the costs associated with CO(2) sequestration. The objective of this paper is to study the economic feasibility Of CO(2) sequestration in unminable coal seams in the Powder River Basin of Wyoming. Economic analyses Of CO(2) injection options are compared. Results show that injecting flue gas to recover methane from CBM fields is marginally economical; however, this method will not significantly contribute to the need to sequester large quantities Of CO(2) Separating CO(2) from flue gas and injecting it into the unminable coal zones of the Powder River Basin seam is currently uneconomical, but can effectively sequester over 86,000 tons (78,200 Mg) Of CO(2) per acre while recovering methane to offset costs. The cost to separate CO(2) from flue gas was identified as the major cost driver associated with CO(2) sequestration in unminable coal seams. Improvements in separations technology alone are unlikely to drive costs low enough for CO(2) sequestration in unminable coal seams in the Powder River Basin to become economically viable. Breakthroughs in separations technology could aid the economics, but in the Powder River Basin they cannot achieve the necessary cost reductions for breakeven economics without incentives. (C) 2008 Elsevier B.V. All rights reserved.