The use of geothermal energy in co-generated heat and power production in Poland : a case study

The paper presents the results of energy and environmental evaluation of geothermal CHP plant. The variant of CHP plant based on Organic Rankine Cycle (ORC) has been taken into consideration as the most favorable for the geothermal conditions prevailing in Poland. The existing geothermal well located in the city of Konin in Greater Poland (Wielkopolska) voivodship has been chosen as the case study. The conceptual design of CHP plant has been proposed and evaluated from energy and environmental point of view. The non-renewable primary energy consumption has been chosen as energy performance criterion. In the case of environmental performance carbon dioxide emission has been taken as evaluation criterion. The analysis has been performed for different operating conditions and three working fluids. The best energy performance can be spotted for working fluid R123, for which the reduction varies between 15200 and 11900 MWh/a. The working fluid R134a has a worse energy performance, which allows for the reduction of fossil fuels energy consumption in the range of 15000 and 11700 MWh/a. The total reduction of CO2 emission is the highest for working fluid R123: 5300 to 4150 MgCO2/a, the medium one for working fluid R134a: 5200 to 4100 MgCO2/a and the lowest for working fluid R227: 5000 to 4050 MgCO2/a. It has been shown that the construction of geothermal CHP plants based on Organic Rankine Cycle can be reasonable solution in Polish conditions. It is important concerning the need of reduction of fossil fuels primary energy consumption and carbon dioxide emission.