The research is aimed to study the process of change in temperature mode dynamics for the Earth subsurface layer when heat is extracted with geothermal heat pump systems, reveal and disclose specifics of effect on the ecology caused by technologies using geothermal resources and give practical recommendations regarding further development of methods for designing heat pumps using low potential heat energy of soil based on the long-term forecast and efficacy assessment. Mathematical statistics and mathematical model methods were applied for assessment of economic and environmental effects. Methods based on principles of the theory of thermal conductivity, hydromechanics, theory of differential equations and mathematical analysis were applied for calculation of proposed systems and review of field observation findings. The authors had developed for research purposes an experimental geothermal heat pump system consisting of four structurally connected geothermal wells, each with installed U-shaped twin collectors of 200 m overall length, and a heat pump of 14 kW capacity with a heat energy battery for 300 L connected to the building heat-supply system. They also created a computer data archivation and visualisation system and devised a research procedure. The paper provides assessment of the effect caused by changes in the process operation mode of the heat pump system on the soil temperature near the geothermal well. As a result, the authors have found that the higher the intensity of heat energy extraction, the lower the soil temperature near the geothermal heat exchanger, in proportion to the load on the system. Moreover, it has been determined by experimental means that at critical loads on the geothermal heat exchanger the soil temperature is unable to keep up with regeneration and may reach negative values. The research also determined relation between inservice time and season of the system operation and temperature fluctuations of geothermal field. For example, it has been found by experimental means that the heat flow from the well is spread radially, from the well axis to its borders. Additionally, it has been proved that depending on the heat load value, the bed temperature is changed after the time of the first launch. For example, the geothermal field temperature has changed from the time of the first launch during 1-year operation by 0.5 °С in average. The research has proved that depending on the heat load value, under seasonal operation (heating only or cooling only) of the system, the soil temperature has decreased for five years by 2.5 °С and switched to quasi-steady state, meanwhile, stabilisation of the geothermal field in the state under 1-year operation (heating and cooling) occurred yet in the 2nd year of operation. In conclusion, the paper reasonably states that geothermal heat pump systems using vertical heat exchangers installed into the wells put no significant human-induced load on the environment. At the same time, still relevant are issues of scientific approach to development of the required configuration of the geothermal collector, methodology for its optimal placement and determination of efficacy depending on operation conditions.

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This article focuses on current issues of alternative geothermal heating development, by using low-potential thermal energy of upper aquifers by heat pumping technology. This type of heat supply is sustainable, does not require fossil fuel consumption and does not pollute the environment. In recent years, heat pumping technologies have become common. A lot of heating systems are implemented, using low potential energy in the air, open bodies of water or soil. Although, now, the heat of groundwater in upper aquifers is a more efficient and reliable source of energy for heat pumps. It was tested in this study. The purpose of this study is to impact assessment of the heat regime of the ground upper layers on efficiency of operation of heat pumping units, using groundwater of near-surface horizons. The factors founded, which form the natural heat mode within the studied area, also the correlation established between temperature changes in the horizon and the operation of the heat pump unit, based on the experimental heat pump unit, established by the Institute of Renewable Energy of the National Academy the Sciences of Ukraine. The article presents an experimental hydrothermal heat pump system developed and constructed at the Institute of Renewable Energy of the National Academy of Sciences of Ukraine, which consists of a heat pump and two wells through which water circulation from the underground horizon to the heat pump. The study describes the characteristics of measuring equipment installed on a hydrothermal heat pump system and described developed an interactive scheduling system based on the software product ESM (Engineering Systems Manager) using the programming language FBD (Function Block Diagram | Continuous Function Chart). This software product was used to create the visual system and archival data system that were obtained in the course of this work. The benefits of this study are that the experimental installation uses the thermal energy of groundwater of the Poltava-Kharkov aquifer as the primary energy source. The interval of the productive horizon is 32-57 m. The groundwater level in the horizon is set at about 40 m. In addition, the air temperature between the pipe space of the observation well and the groundwater temperature in the aquifer are monitored. The duration of regime observations was six months, the frequency of measurements – 5-15 seconds. The monitoring results indicate that despite the fact that the productive horizon is at a depth that significantly exceeds the usual depth of the neutral layer for the territory of Ukraine, the for- mation temperature is not stable and its amplitude is 2 oC. According to the authors, the increase in the depth of the surface of constant annual temperatures may be due to local features of the studied area, namely: increasing the absorption surface of solar radiation due to terrain, the presence of lateral heat inflow, the presence of water-saturated layers in the upper part. Consequently, based on the analysis of geological and hydrogeological conditions of the site, as well as technological processes occurring in the installation, the main factors that form the natural temperature of the upper layers of the earth are identified. As a result, the percentage of energy efficiency drop of the installation is calculated depending on the decrease in the temperature of the natural heat carrier in the aquifer. It is established that it is necessary to conduct additional research to assess the environmental impact of the use of aquifers for energy purposes and to ensure the optimal mode of operation of aquifers, which would be as close as possible to their natural regime.

In the bowels of the Earth and in the oceans of the World Ocean, there are practically unlimited resources of natural gas in the solid hydrate state, available to most countries of the world community. The development of gas hydrate deposits is based on the process of dissociation (separation), in which the gas hydrates break down into gas and water. In these technologies, three methods for the development of gas hydrate deposits are proposed: pressure reduction, heating and inhibitor input. Based on the systematized data, the above methods are suggested to be attributed to traditional methods, as the most studied and classical ones. It is proposed to identify a number of methods that imply the same results, but use other physical approaches and designate them as unconventional. 1. Decomposition of methane hydrates by nanoparticles. In this method, the use of nanoparticles commensurate with the gas hydrate cell (supplied as part of a hydrodynamic jet) is proposed for efficient and safe destruction of the gas hydrate. The application of nanotechnology provides effective and consistent study of the entire surface of the aquatic deposit of gas hydrates, with the necessary rate of their destruction and the production of planned volumes of methane. 2. Decomposition of methane hydrates by microorganisms (bacteria). In this process, in the process of the life of the bacteria, a gas must be released, replacing in the clathrate structure a molecule of methane per molecule of the given gas. In addition, the process must be controlled by the use of external factors that provide nutrition to the bacteria and at the same time, light, chemicals, electromagnetic radiation, etc. can be stopped at any time, which is absent in the natural conditions of formation of the gas hydrate.

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