Deposits of geothermal water in Uniejów were discovered at the end of the 1970s. But not earlier than in the years 1990-1991 two bore holes were drilled making the extraction end use of geothermal water possible.
Geotermia Uniejów Sp. z o.o., officially a mining company was established in 1999. The main shareholder is the municipality of Uniejów (58.8%), while the remaining part belongs to the Provincial Fund for Environmental Protection and Water Management.
Renewable energy sources
Geotermia Uniejów is the first heating plant in Poland using only renewable energy sources: geothermal water and biomass. Currently, the total power of the heating plant is 7.4 MW of which 1.8 MW comes from the combustion of biomass and 3.2 MW of geothermal energy. In addition, there are oil boilers of 2.4 MW, but they have only a reserve function.
In Uniejów we use the doublet system consisting of a production well from which hot water and steam is extracted from the ground, a surface heat exchanger and a reinjection well which through which all cooled thermal water is pumped back to the aquifer. This system has several benefits. The reservoir pressure energy can be preserved, the deep circulation systems of the surroundings around the aquifer are not disturbed. As a result, obtaining energy is environmentally friendly and also reduces the risk of running out of underground resources..
In Uniejów there are two boreholes located about 1 kilometer from each other:
- PIG / AGH-1 – is located in the northern vicinity of Uniejów. This injection well was drilled in 1991 and its depth reaches 2,065 m.
- PIG / AGH-2 – is located in Uniejów, on a terrain belonging to the company. It is a production well from which water is extracted. It was drilled in 1990 and is 2,031 meters deep.
In Uniejów, the so called cascading geothermal technology is applied. After extraction to the surface, it is directed to heat exchangers, where it heats treated fresh water. With the help of pumps the water heats residential and public buildings as well as hotels. This is the first stage of geothermal water use. It is estimated that the number of recipients in single-family and apartment buildings is over 2000 people (about 70% of all town residents).
After cooling to 50ᴼC, geothermal water is directed to therapeutic and swimming pool facilities, where it is used for recreational and rehabilitation purposes. This is the second stage of water use. Due to the fact that the geothermal water is still warm (ca. 35ᴼC), during the winter it is used to heat the football pitch. This is the third stage of its use.
Composition and properties
The geothermal water deposits in Uniejów are located at a depth of about 1700-2250 meters below the surface of the earth. The outflowing water has a temperature of about 68-70ᴼC and mineralization of about 8g / l. Water flows out at a pressure of 2.6 atmospheres.
Uniejów’s thermal water is chloride-sodium mineral water with exceptional healing properties confirmed by required certificates. Due to its high temperature, it affects our body not only chemically, but also thermally.