In order to study CO2 capture from a gas mixture by hydrate crystallization, we conducted separation experiments using TBAB as an additive, which makes the hydrate crystallization condition milder. Based on experimental results, we did flowsheeting simulations to evaluate a realistic energetic costing and compare with other classical technologies (membranes, amines, etc.). We also estimated investment cost and production cost of the gas capture system for different kinds of blast furnaces. (c) 2006 Published by Elsevier Ltd.