A method of removing siloxanes from a gas that contains siloxanes and water, the method comprising: (a) expanding the gas to cool the gas and freeze at least some of the water in the gas; and (b) removing the siloxanes and frozen water from the expanded and cooled gas. The method may also include compressing the gas prior to expanding it. The step of expanding the gas may include expanding it through a turbine. The method may also include using an energy input mechanism to drive one or both of the compressor or turbine. The ice and siloxanes may be removed from the gas with a cyclonic separator.