Abstract: A method which allows the ejection of non-condensable gases, notably air, from a closed loop power generation process or heat pump system, is disclosed. A vessel in which a working fluid is absorbed or condensed can be separated from the power generation processes by valves. Residual gas comprising C02, non-condensable gas such as air, water and alkaline materials including amines may be compressed by raising the liquid level in said vessel. The concurrent pressure increase leads to the selective absorption of C02 by alkaline materials. In simpler embodiments, mainly air is removed from one- or two-component processes. Following the compression, non-condensable gas may be vented, optionally through a filter. The method is simple and economic as vacuum pumps may be omitted. The method is useful for any power generation and Rankine cycle, and particularly useful for the power generation process known as C3 or Carbon Carrier Cycle.