This paper examines the use of geothermal water to replenish network water losses in the largest Polish geothermal heating system. The geothermal installation capacity (under artesian conditions) is 670 m³/h. The total power of the geothermal water source is 15.4 MW, and it is assisted by peak load boilers. The total capacity of the heating plant is 80.5 MW, and energy output amounts to 324 TJ/year. The system serves ca. 1,500 customers and includes ca. 95 km of district heating distribution network (Fig. 2). Distribution network water losses amount to ca. 6,600 m³/year. The water used to replenish the losses is currently treated using ion exchange water softeners and vacuum degasifiers. It is suggested that the missing water be replaced with treated geothermal water; following treatment, this water must meet the requirements set forth in the water quality standards for heating systems (PN-85/C-04601 – Table 1).
The treatment uses membrane processes within the framework of a double hybrid arrangement, including ultrafiltration and reverse osmosis. Artesian pressure is used to a certain extent during treatment, which makes it possible to reduce the power required for the distribution pump, decreasing electrical power consumption. Thus, the requirements set forth in the standards have been met and the treated geothermal water can be used to replenish network water losses in the district heating system following pH adjustment and degassing.