The Prospects of Thermal Water Exploration in Ukraine

Abstract

The total resources of geothermal energy in Ukraine up to the depth of 10 km are estimated at 1022 J, which significantly exceeds the reserves of fossil fuel sources. Nevertheless, geothermal exploration in each specific case requires comprehensive thermodynamic and feasibility studies taking into account local geological, hydrogeological conditions, and depth ranges. To facilitate such kind of studies an analysis has been made for Ukraine’s territory with the identification of aquifers that can be potentially used including the Transcarpathian trough, the Volyn-Podil’ska plate, the Dnipro-Donets depression, and Black Sea coast area. Regarding high thermal water mineralization a geo-technological scheme has been justified for environmentally safe exploration that suggests a closed cycle including (i) pumping out water to the surface, (ii) heat extraction, and (iii) re-injection of water into the aquifer. A mathematical model developed to evaluate the geo-circulation system effectiveness for various conditions allows predicting the changes in water temperature during circulation, power consumption, and heat capacity. Besides, the model enables optimizing the system performance depending on pumped water temperature. We assessed the effectiveness of geothermal heat extraction with the geo-circulation system in terms of profitability and net the present value (NPV). According to the estimations made for aquifers in Ukraine the geo-circulation system can be operated with the positive NPV in many regions of the country depending on the aquifer depth, heat flux, and groundwater flow. The obtained results correlate to the world standards of rational exploitation of geothermal energy.