Gas hydrates technologies in the joint concept of geoenergy usage

. The paper represents the analysis, which has helped to establish the usage of gas hydrate technologies in the methane conversion. This gas could be obtained in different ways. Possibilities and sources for the gas obtaining have been demonstrated. Use of other environmentally friendly sources to support operation in such systems in terms of joint energy complex has been considered. The necessary kinetic connections to provide operational sustainability of all the constituents have been given. The approach helps evaluate quantitatively the priority of its physicochemical transformations to obtain gas hydrates artificially. It is possible to transport methane at considerable distances when it is solidified. Actually, in this case there is no necessity to build costly compressor stations and pipelines for its transportation to consumers. The approach is extremely important for mining regions as it helps prolong the operating period and working out of the abandoned and off-balance coal reserves. In this case, it is proposed to apply special gasification technologies tending to maximum methane recovery. The proposed solutions give the possibility to define the trends of our further research. They will be highlighted in the following authors’ studies.


Introduction
The improved social responsibility should change drastically the approaches of subsurface use as well as extraction of various minerals. The development of power sources, which will provide formation of hi-tech production, has to be environmentally friendly as much as possible [1][2][3][4]. Moreover, social aspects of functioning of the urbanized territories, within which minerals are mined, should also be involved [5,6]. Practically any human activity results in the emission of greenhouse gases [7,8], accumulation of wastes on the daily surface as result of mining activity [9][10][11][12]. Great attention is paid to the utilization of carbon dioxide [13][14][15][16].
The paper is aimed at analyzing the emission sources of methane, being another greenhouse gas, and identifying the possibilities of its further transformation into solid state for its further industrial use. These are gas hydrates technologies that make it possible to solve the stated problems [27][28][29][30][31].
CH 4 catching and transforming into another aggregate state makes it possible to solve the problem of its adsorption and transportation at long distances with further industrial use. Such an approach allows considering treatment of that energy gas in the innovative way with the formulation of a unified system of its obtaining from different sources of human activity. Final objective of the research is to develop a concept of joint system for extraction, adsorption, transformation, and transportation of methane with the help of gas hydrate technologies with its following industrial use.

Development of joint technologies for the geoenergy usage based on gas hydrates transformation
At all times, progress of human civilization has been followed by the increased production and consumption of power resources. According to the technological improvement, that makes us search for solution for all the mining-accompanied problems along with the solution of economic, ecological, and social issues [22,32,33].
Unfortunately, professional reorientation of miners is rather a complex and long-term process. It results in the increased social tension in mining regions [34,35]. In increasing frequency, we face a problem of human consciousness manipulation with the help of modern Information Technology); moreover, instability and dissatisfaction of certain population layers may also be used to solve certain political problems. There are examples when miners have been involved in the sanctioned suppression of democratic expression of a social opinion. Disrupting manifestations in Romania at the time of the end socialist ideology in the Central and Eastern Europe with the help of miners is one of the latest and brightest examples.
The problem, being considered by the paper, involves both engineering aspects to form technical and technological provision of fuel and energy systems as well as political and social economic-ecological aspects able to model political situation and stability both in certain states and in regions on the whole. The research is aimed at reorienting the miners' activities taking into consideration the mentioned problems of creating new jobs by implementing gas hydrate technologies in mining and post-mining operations.
In our previous studies attention was paid to different cogeneration technologies conducted with the mining enterprises operation [24,30,[36][37][38][39]. The specialized literature [37,[40][41][42][43][44] pays attention to the application of joint technological plants which means the usage of different renewable. Traditional energy sources with the consideration of the environmental management are fully described in the references [45][46][47]. This paper means the possibility of introduction the innovative technological issue of gas hydrates transforming with zero energy using.

Alternative coal power sector and other sectors for gas hydrates energy supplying
Development of such a production together with traditional coal power sector should be based upon wasteless methods helping solve both economic and social problems. First, it concerns environmental protection. The fact is of principal importance while selecting a strategy to form complex production focusing the science on the development of engineering solutions aimed at the progress of business links, using the waste as a primary raw source, rather than on the decreased waste production within the isolated technological cycle. The production development will be of interbranch integration nature of a complex, combined (i.e. cogenerative), and wasteless mining energy-chemical manufacture with the use of raw materials in terms of maximum implementation of the produced waste for economic circulation.
Ukrainian mining industry has several more alternatives of operation schedules concerning cogeneration of energy carriers. In addition to the mentioned well coal gasification, combined with steam and electricity generation and thermal energy accumulation, they are as follows: methane extraction and use in the process of gas-coal and shale deposit development; thermal energy generation in the process of geothermal deposit mining; use of low-potential heat of rocks of the Earth, water, and air; use of gasturbine engines for traditional generating facilities; and use of thermal pumps to utilize lowpotential heat of mine water, artesian water, ventilation emissions, thermal water during compressor cooling etc.
In addition to gas turbines, gas powered engines can also be used in cogeneration schemes for electric generator drive [48,49]. Lower oxygen content in combustion products is the engine feature since air excess coefficient is not more than 2.0-2.2. Examples of the efficient application of cogeneration plants in the industrialized countries mean that up to now they are still among the most promising and resultative ways to improve the efficiency of fuel use in the context of power industry. Modern world cogeneration plants have expensive automatic process control systems (APCSs) making it possible to optimize processes of power generation as well as control the plants remotely. APCSs can also combine several plants into one power object which prolongs their operation period and reduces fuel consumption drastically.
Unfortunately, only several cogeneration plants operate in Ukraine. However, possibilities for their wide implementation are unique. In our country, a system of centralized heating, basing upon powerful TPPs and boiler houses, functions. Thousands of heating (water heating mainly) tanks, which capacity is from several to hundreds of megawatts (maximum capacity is 100-150 MW) are mounted in municipal boiler houses. They can be updated with simultaneous secondary structures and application of power generating thermal engines.
It is the most expedient idea to use heat pumps for objects with low thermodynamic potential. In this case, basic and time-constant area of underground low-potential heat extraction is formed with the help of different use of heat exchangers [50][51][52][53][54]. Definitely a special attention must be paid for chose the materials for pumps design [55][56][57].
Hence, the basic advantage of HP-plant to compare with heat generation with the use of traditional boilers is as follows: the heat pumps make it possible to produce similar heat amount just using 2/3 of extra low-temperature potential, and 1/3 of electric energy consumed by the HP plant compressor [58,59]. Fig. 1 explains difference between heat supply by the heat pumps and the available energy sources. As it is seen, heat pump plants with the use of renewable energy sources are the most efficient ones. Taking into consideration the world tendency as for crude oil and gas price escalation, efficiency of the systems will experience constant increase. Hence, production of such heat pumps with different working capacities and corresponding energy characteristics is one of the topical tasks [23, 41,[60][61][62].
The carried out calculations show that extra capital charges for heat pump plants will be paid back during 4-8 years. In this context, annual electrical energy savings will be UAH 85 thousand, if HP plants are applied. Variable capacity of wind power plant as well as current and voltage oscillations follow from the fact. SWPPs are of significant material intensity since their strength should provide impulse impacts of wind flow. Moreover, they uglify landscape, make noise, and provoke electromagnetic interference for TV and radio channels.
The authors believe that perspective progress of wind power sector may result from its use at mining enterprises. Arrangement of WPPs in mine workings of near wellbore area improves their operation conditions substantially. Mine ventilation flow involves significant reserve of constant kinetic energy; moreover, it is powerful source of rotation of underground wind power plants (UWPPs). Besides, velocity and direction are constant. Thus, wind wheels rotate regularly with no fluctuations and current or voltage oscillations. Hence, reliable highefficient and cheap resource for electric power generation is obtained in mines transiting currently from their mining and other production processes to radically new functions. After their shutting down, they become enterprises of environmentally friendly wind power [63][64][65].

Thermal energy sector
To revive intrastratal pressure of geothermal deposit in summer, it is foreseen to add solar (helio) plants to operation. Systems with air-water heat pumps should be applied for hot water supply when the weather is grey. Solar collectors are mounted on the overhangs located at 3.5-4.2 m height over the ground. Photoelectric 1 kW transformers are planned for electric power supply of circulating pumps of the solar plant. Ventilation flow, leaving mines, subways, and other underground structures, contains much extra thermal energy as for the environment. In terms of large mines, such a potential is 9.1·10 4 МW·h/year. The energy is lost irrevocably when mine ventilation flow is discharged to the atmosphere.
Apart from that, mine atmosphere contains enough methane. Nowadays, it can be also a source of additional energy raw material. Gas hydrate technologies help solve quite successfully a problem of gas solidification with its further long-distance transportation [66]. As a result, a problem arises concerning the creation of a complex system for the methane formation and use in terms of the closed ecological, energy-saving, and hydrating complex.

Development and application of the energy-saving hydrating complex
The basis may help develop innovative industry, i.e. thermochemical energy, making it possible to reduce dependence upon the imported crude oil and natural gas. The industry will develop construction and operation of fuel and energy complex on the basis of gas hydrate technologies which will involve use of methane from different sources including gasification of coal seams relying upon the progressive combined technology, and modern interbranch form of production management with complex processing of raw materials as well as complete waste utilization (Fig. 2). The gas, discharged from gas turbine (СО 2 ), does not get to the atmosphere. It is directed to underground gas generator. While interacting with hot coal, the gas is decomposed into combustible gases СО 2 + С = 2СО + О 2 . As it is understood, the waste (СО 2 ) may be profitable, if it is used to generate combustible gas applied by consumers.
Production integration, being one of the key tendencies to organize thermochemical manufacturing of synthetic hydrocarbons, makes it possible to form certain wasteless enterprises on the basis of: -complexes generating artificial gas, i.e. energy carrier and synthesis gas (СО + Н 2 ) based upon UWCG with utilization of solid and smoke waste of power technological production; -gas hydrate conversion for the natural gas substitute; -complexes of organic synthesis of fuel products and chemical substances; -gas and steam turbine plants generating electric energy and thermal energy; -pilot plants to produce hydrogen, resin, carbon, polymers, fertilizers, feed proteins etc. Thermochemical energetics may be qualified as environmentally friendly technologies (i.e. ecotechnologies) in terms of which production processes follow the principles of nature functioning: closeness, gradation, and complexity. In this context, all the interactions function jointly. It will help liquidate hard and dangerous work of miners, save nature from waste, level down morbidity rate, and improve wildlife health. The energetics is aimed at radical thinking alternations while solving environmental problems falling into the progress of geoenergetics: hazardous industries (i.e. mines, open casts, coal-preparation plants, thermal power stations, nuclear power stations etc.) should not be reconstructed with billions of expenses; it is more expedient to develop environmentally friendly activities on the basis of underground coal gasification which will provide stability and health of the environment [30,67,68]. Coal seam gasification is aimed at harmonious interaction between community and nature, human and environment as well as environmental improvement. A concept of waste control has also varied: waste prevention or utilization as raw material rather than its neutralization. Use of gas hydrate technologies in this cycle makes it possible to widen considerably the application range of methane from different energy sources.

Conclusions
National economy should rely upon the available proper sources (i.e. thermal energetics and nuclear energetics) as well as upon broad development of alternative energy sources. Moreover, it is important thing to combine them into cogeneration systems to provide their stable operation. Specific attention should be paid to the progress of radical methods of coal processing right in site (i.e. underground gasification and surface gasification). Use of gas hydrate technologies, in terms of which methane obtained from different sources is solidified, proposes new approaches to the formation of innovative possibilities while creating energy sources.
The paper represents the analysis aimed at determining the use of gas hydrate technologies during transformation of methane obtained by different methods. That approach helps prolong the operating period of mines with depleted residuals or the ones being under closure. The proposed technologies of generator gas extraction by anaerobic digesting of organic substances in methane-tanks as well as other approaches to the combined formation of new energy systems allow reorienting the mine operation. That approach is of prime importance for rather depressed mining regions as it helps solve the problem of social strain. Formation of joint energy and chemical production makes it possible both to improve economic expediency and prevent negative environmental impacts on the surface and underground mine environment. The proposed tendencies allow outlining related problems to be highlighted in further studies carried out by the authors.