Economic analysis of a supercritical coal-fired CHP plant integrated with an absorption carbon capture installation

Energy investments in Poland currently are focused on a supercritical coal-fired unit technology. These units in the future are to be integrated with the carbon capture and storage (CCS) installations, which according to assumptions allow achieving a significant reduction of this greenhouse gas emissions into the atmosphere. A significant share of energy market in Poland constitute coal-fired combined heat and power (CHP) plants based on blocks, of which electrical power does not exceed the level of 135 MW. The integration of these units with CCS installation can be economically inefficient. On the other hand, the lack of such integration enhances the investment risk due to the possibility the high price of CO2 emission allowances in the near future. Mentioned factors and additional favorable conditions for development of cogeneration allow to think about investing in a large supercritical CHP plants. In the case of plants with extraction-condensing steam turbine the major problem is choosing of a method of integration of the unit with CCS installation. Here, particularly the choice of a separation method is important. The most suitable methods for the CHP plants are those methods which for separation process require the electric energy. Unfortunately, technologies based on these methods, such as membrane or cryogenic technologies are in the research process and their commercial implementation are not expected in the near future. Separation technology which is closest to commercialization is a technology that uses the chemical absorption method. Realization of separation process requires the large amount of heat supply to a stripper column. In the case of power plants in solutions proposed by the designers the heat source is steam bleed from the steam turbine. Unfortunately, in the case of CHP plants steam which potentially can be used for the process of desorption is used for production of useful heat. For a supply with steam of both district heating heat exchanger and desorption column, building of a much larger block is required. In the paper the results of economical analysis aimed at comparing the three cases of CHP plants integrated and not integrated with the CCS installations are shown. The same structure of steam cycle and numerical assumptions for all variants are adopted. The first solution is a CHP plant without integration with CCS installation, second solution is CHP plant integrated with CCS installation and third solution is CHP plant integrated with CCS but additional in relation to second case with useful use of heat recovered within CCS installation. For evaluation of respective solutions two indicators, i.e the break-even price of electricity and emission avoidance cost were used.