Extraction of thermal energy from the ocean using gas hydrates (original) (raw)
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Mining of methane from deposits subaquatic gas hydrates using OTEС
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The article proposes to using Ocean Thermal Energy Conversion (OTEC) to increase the energy efficiency mining of methane from deposits subaquatic gas hydrates on the gas hydrate cycle (GHET), that will allow not to spend 10-15% of the extracted methane for power supply of a gas-producing complex (GPC). The circuit-technological solution GPC is described, according to which carbon dioxide is introduced into the gas hydrate layer to extract methane from gas hydrates. To improve the kinetics of the process of replacement of methane with carbon dioxide in gas hydrates, it is proposed do recirculation part of CO2. The scheme and cycle of gas-hydrate energy-technological installation GHET are given, which operates using OTEC and generates together with electricity for GPC, fresh water and cold. Based on the method proposed in this paper, a comparative thermodynamic analysis of installations using OTEC for Black Sea conditions was performed. by GHET and Anderson cycles and it is shown that...
A PRE-REVIEW STUDY OF OCEAN THERMAL ENERGY CONVERSION CYCLE WITH DIFFERENT WORKING FLUIDS
Malaysia has huge potential for developing Ocean Thermal Energy Conversion (OTEC) although it has not been established yet. The OTEC plant can be installed to operate between a heat source (surface seawater at 30°C and heat sinks (deep seawater at 1000m for 4°C). This ocean thermal energy is cheap and most importantly it is sustainable -as long as the sun keeps heating the ocean surface. The current best performance between all the OTEC cycles is that of Uehara Cycle which uses ammonia mixture as the working fluidhighly toxic. Therefore, the purpose of this paper is to explore the other potential friendly working fluids. The research is to improve performance of OTEC plant and at the same time the plant is operated using an environmentally safe working fluid. The results should lead to future development an OTEC plant at Malaysia.
Energies, 2010
A method is proposed that uses renewable solar energy to supply energy for the exploitation of marine gas hydrates using thermal stimulation. The system includes solar cells, which are installed on the platform and a distributor with electric heaters. The solar module is connected with electric heaters via an insulated cable, and provides power to the heaters. Simplified equations are given for the calculation of the power of the electric heaters and the solar battery array. Also, a case study for the Shenhu area is provided to illustrate the calculation of the capacity of electric power and the solar cell system under ideal conditions. It is shown that the exploitation of marine gas hydrates by solar energy is technically and economically feasible in typical marine areas and hydrate reservoirs such as the Shenhu area. This method may also be used as a good assistance for depressurization exploitation of marine gas hydrates in the future.
Electricity Generation by the Ocean Thermal Energy
Energy Procedia, 2011
With considering the increasing of global temperature, and also the concern of global climate change, many policy makers worldwide have been accepted the importance of reducing greenhouse gas emissions, in particular from the power industries. Energy resource use is one of the most important and Contentious issues of our time. The ocean provides a vast source of potential energy resources. Of the total solar radiation, oceans are the largest collectors, accumulating 250 billion barrels of oil equivalent, according to an estimate. This vast amount of solar energy absorbed in the oceans can be converted into electricity by a process known as Ocean Thermal Energy Conversion, popularly known as OTEC. OTEC makes use of the difference in temperatures of warm surface water (22-27 °C) and very cold water at a depth of 1 km (4-7 °C). an open-cycle plant based on creating a rising mixture of water and steam bubbles or "foam", which is separated at a height above sea-level, such that the water can be used to drive a turbine rotor. In closed-cycle OTEC, warm seawater heats a working fluid with a low boiling point, such as ammonia, and the ammonia vapor turns a turbine, which drives a generator. This paper discusses about the ocean energy, ocean thermal energy potential, ocean thermal energy conversion by the close, open and hybrid cycles, environmental impact and special conditions of these process.
Ocean Thermal Energy Conversion Primer INTRODUCTION
The vertical temperature distribution in the open ocean can be simplistically described as consisting of two layers separated by an interface. The upper layer is warmed by the sun and mixed to depths of about 100 m by wave motion. The bottom layer consists of colder water formed at high latitudes. The interface or thermocline is sometimes marked by an abrupt change in temperature but more often the change is gradual. The temperature difference between the upper (warm) and bottom (cold) layers ranges from 10 °C to 25 °C, with the higher values found in equatorial waters. This implies that there are two enormous reservoirs providing the heat source and the heat sink required for a heat engine. A practical application is found in a system (heat engine) designed to transform the thermal energy into electricity. This is referred to as OTEC for Ocean Thermal Energy Conversion.
A method of harvesting gas hydrates from marine sediments
Gas hydrates bind immense amounts of methane in marine sediments. If produced cost effectively, they can serve as a stable energy supply. No viable technologies for extracting gas hydrates from deep ocean deposits have been developed to date. Due to the shallow depths, low hydrate concentration, low permeability of the gas hydrate stability zone, lack of driving pressure and the slow melting process, low productivity is anticipated for gas production from gas hydrates in marine sediments. Therefore, only a large number of low cost wells can support an offshore production facility and pipeline transport to shore. The method of harvesting natural gas from sea floor gas hydrates presented in this paper is a combination of several new concepts including electrically adding heat inside hydrate rich sediments to release gas, using an overhead receiver to capture the gas, allowing gas to form hydrates again in the overhead receiver, and lifting produced hydrates to warm water to release and collect gas. This approach makes the best use of the nature of hydrates and the subsea pressure and temperature profiles. Consequently, it leads to a simple and open production system which is safe, economical, energy efficient, environmentally friendly, and without significant technical difficulties. Basic analyses and calculations on the feasibility and heat efficiency of the proposed method are presented and discussed.
Ocean thermal-energy conversion
Ocean thermal-energy conversion (OTEC) is a novel 'alternative' energy technology that has created much interest in a number of countries; namely, the USA, Japan, France, Sweden, Holland, India and, most recently, the UK. In particular, the first three of these have had programmes to develop the required technology. However, most interest has been centred in the USA, where the current hiatus in Federal funding provides a timely opportunity to assess progress. This paper offers a survey of the prevailing position there; outlining the outstanding technical and associated problems, and likely future developments. Non-US programmes are only mentioned to contrast them with the American position. At present, it does not appear tnai u m t plants win be commercially viable on a widespread basis even in the tropics. This is particularly true of the larger plants (400 MWe, MWe = megawatts of electrical energy, the final output of a power station) towards which the American programme is ultimately geared. There does seem to be a strong possibility that small OTEC plants, around 40 MWe or less, can be commercial in certain circumstances. This would be possible when one or, preferably, more of the following conditions are met: (i) where a land-based rather than 'at sea' plant is possible, (ii) where alternative energy supplies are at a premium, i.e. islands or regions without indigenous energy supplies, and (iii) where conditions are such that an OTEC plant could operate in conjunction with either or both an aquaculture or desalination plant.
Gas hydrates technologies in the joint concept of geoenergy usage
Roman Dychkovskyi, Mykola Tabachenko, Ksenia Zhadiaieva, Artur Dyczko, Edgar Cabana: E3S Web of Conferences 230 , 01023 (2021), 2021
The paper represents the analysis, which has helped to establishthe usage of gas hydrate technologies in the methane conversion. This gascould be obtained in different ways. Possibilities and sources for the gasobtaining have been demonstrated. Use of other environmentally friendlysources to support operation in such systems in terms of joint energycomplex 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 issolidified. Actually, in this case there is no necessity to build costlycompressor stations and pipelines for its transportation to consumers. Theapproach is extremely important for mining regions as it helps prolong theoperating period and working out of the abandoned and off-balance coalreserves. In this case, it is proposed to apply special gasification technologies tending to maximum methane recovery. The proposedsolutions give the possibility to define the trends of our further research.They will be highlighted in the following authors’ studies.
METHANE GAS HYDRATES OF THE BLACK SEA -ENVIRONMENTAL PROBLEM OR ENERGY SOURCE
The purpose of this paper is to substantiate the technological solution of equilibrium conditions in the system "methanewater phasehydrate-R-2M"; to reveal existing ecological problems of methane gas hydrate extraction from the Black Sea bottom; to determine whether gas hydrate deposits of Black Sea methane are an ecological problem or should be considered as an energy source, to explain the necessity of introduction of the effect of forced self-preservation of methane gas hydrates into development of gas hydrates from the sea bottom. Results. This article analyses current research on gas hydrates specifically in the Black Sea. It shows that the necessary conditions exist for the accumulation of gas hydrates in certain areas of the deep Black Sea (one of the most favourable regions among modern sea basins). This article discusses some ideas for the development of experimental studies of the metastable state of methane gas hydrates at negative temperatures: stability and mechanisms of decomposition. Despite the great variety of technological solutions and schemes of gas hydrates application proposed by the leading researchers in the world, they have been tested practically on a small number of laboratory and model installations, mainly for water desalination and concentration of water solutions, separation of two-component gas mixtures. In fact, there is no data to calculate the processes of formation and melting of ice-gas hydrate methane. The effect of self-preservation of methane gas hydrates deserves special attention. Scientific novelty. An attempt was made to substantiate the issue of whether gas hydrate deposits of methane in the Black Sea are an environmental problem or should they be considered as an additional source of energy and even as a "fuel of the future". The authors for the first time introduced the concept of "forced preservation (activation) effect of methane gas hydrates", which makes it possible to stabilize methane hydrate decomposition when the system is transferred from the area of hydrate stability to the area of thermodynamic parameters, thus significantly reducing the environmental problems of the Black Sea.