Combined Geothermal and Gas District-Heating System, City of Oradea, Romania

Abstract

The City of Oradea, Romania, has a population of about 230,000 inhabitants. Almost 70% of the total heat demand, including industrial, is supplied by a classical East Europeantype district-heating system. The heat is supplied by two lowgrade, coal-fired co-generation power plants. The oldest distribution networks and substations, as well as one power plant, are 35 years old and require renovation or even reconstruction. The geothermal reservoir located under the city supplies at present 2.2% of the total heat demand. By generalizing the reinjection, the production can be increased to supply about 8% of the total heat demand, without any significant reservoir pressure or temperature decline over 25 years. Another potential energy source is natural gas, since a major gas-transport pipeline passes close to the city. Two possible scenarios are envisaged to replace low-grade coal with natural gas and geothermal energy as heat sources for Oradea. In one scenario, the geothermal energy supplies heat for culinary water heating and the base load for space heating in a limited number of substations, with peak load being produced by natural-gas-fired boilers. In the other scenario, the geothermal energy is only used for culinary water heating. In both scenarios, all substations are converted into heating plants with natural gas as the main energy source.