The Geothermal Potential of CO2 Based Heat Pumps Used in an Abandoned Coal Mine

Abstract

Kazincbarcika is a small post-industrial town of about 28,000 inhabitants, located in Borsod-Abaúj-Zemplén county, in NE Hungary. It lies in the Sajó river valley, 20 km (12 mi) from the county capital, Miskolc. Kazincbarcika became economically more important around 1850, when its first coal mine opened. The Socialist era (1950-1970) further stressed the importance of coal mining, but after Hungary's mining industry collapsed in the 1980s, the city's mines were closed. Abandoned, the mine shafts eventually flooded, as the mine has a continuous water supply. The mine can produce 16-22 C* water at a rate of about 55 kg/s from a depth of about 200-300 m in the Miocene, 20-28 C* water at a rate of about 55 kg/s from a depth of 450 m in the Oligocene, and 18-20 C* water at a rate of about 50 kg/s from the abandoned Tervtáró (Radvánszky táró) shaft. The terrestrial heat flow is relatively high: 0.108 W/m2. The heat transfer surface is more than 150,000 m2. With CO2 based heat pumps, the abandoned mine's geothermal potential could help create a district heating system which would easily meet Kazincbarcika's heating and cooling demands.