Geothermal project in Sered

Town of Sered is situated in Danube lowland on the right side of Vah river. From geological point of view it is clear that the town lies in the prospective area for geothermal energy utilization. There are six existing district heating system in the town, each with central boiler plant and two-pipe hot water distribution network connecting to apartment and puplic building in the surroundings. Based on most convenient parameters (heat output and locality), boiler plant K5 was chosen for geothermal energy usage.

Complete project documentation for building permission was elaborated in 2009 and geothermal well was drilled in the end of 2010. Currently, during the year 2011, the implementation of above ground technology is taking place. Investor and former operator of the geothermal project is company MBP Sered.

Geothermal energy form new well SEG-1 with depth of 1 800 m will be used for heat production in existing boiler plant K5. Geothermal water will be pumped by electric submersible pump with variable speed controller. Flow rate is 8 l/s and temperature 66°C. Water will be delivered via pre-insulated pipe to a separator, where the free gases will be released, and subsequently to a heat exchanger station situated in the area of the boiler plant. After the utilization of thermal energy in heat exchangers, geothermal water flows through plastic pipe into the recipient, Vah river. Length of supply pipeline is approx 330 m and of discharge pipeline 430 m.

Boiler plant K5 is central heat source supplying the heating hot water with design temperature gradient 90/70°, while the real value does not exceed 65/45°C. Primary two-pipe distribution network is connected to pressure dependent heat exchanger stations installed directly in supplied buildings (17 apartment buildings, 4 public buildings) with 960 apartments. Average annual heat production of K5 reaches approx. 39 000 GJ (10 833 MWh), while geothermal energy covers approx. 45%.

Two demountable plate heat exchangers made of titanium are installed in geothermal heat exchanger station, the first of which with 0,85 MW heat output for direct return heating water warming and the second with 0,4 MW for heat pump evaporator loop water warming. The heat pump´s maximal heating output in given conditions is 547 kW. Total heat output given into the system by geothermal energy and the heat pump is 1,4 MW.

Geothermal energy combined with the heat pump represents the base load heat source with the maximal working time throughout the year. The existing natural gas boilers are being used as a peak source or possibly as a backup source able to cover 100% of heat demand.

With respect to the parameters of geothermal resource and district heating system, it is impossible to completely replace natural gas usage. However, significant savings of such primary fossil fuel are being reached which of course positively impacts the economy of the heat plant operation. Environmental aspect in reducing CO2 emissions is also important. Geothermal energy, as one of the cleanest and most stable renewable energy resources, covers 45% of overall annual heat production of K5, while savings of 547 000 m3 of natural gas per year and CO2 emissions reduction of 1 078 ton per year are achieved.

The geothermal project in Sered together with recently implemented project in Sala demonstrate the economical and technical favorableness of reasonable and professionally solved geothermal projects, despites of lack of interest from the state.