Economic evaluation of different-scale gas-steam power plants including costs of decommissioning replaced units

The prospect of increasing energy efficiency and reducing power plant emissions (including CO2) results in an increased interest in technologies using natural gas. In addition, in view of the possibility of exploitation of shale gas deposits that could lead to a reduction in fuel costs, economic analyses of the construction of new gas-steam systems seem very interesting. An important factor affecting the profitability of new installations is the selection of the power output capacity of the planned units. This factor is also essential if the investor’s capital resources are rather limited. If it is impossible to introduce new units into the power generation system, it is important that the economic analysis should take account of the costs related to a premature decommissioning of power units. This paper presents an analysis of two gas-steam systems with a different power output capacity. The minimum selling prices of electricity are determined. For decommissioned power plants, the conditions (i.e. electricity costs) which make investments in new gas-steam systems equally profitable are defined.