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根据海洋温差能转换(OTEC)工艺过程的特点,分析了海洋温差能开发对海洋生态环境的特殊影响。认为大流量吸排水形成的大尺度水团在海洋中的重新分布,致使厂址周边海水的层化结构和环流结构以及海水盐度、溶解氧和营养水平等参数发生变化,进而对海洋环境造成很大改变,形成了OTEC技术特殊的环境影响方式。还着重分析了羽状流对初级生产力的影响,以及卷载和冲击对海洋生物的影响,分析归纳了海洋温差能开发生态环境影响的关键评价因子,对下一步的研究重点提出了建议。为未来开展洋温差能开发以及全面评价海洋温差能开发造成的生态环境影响提供技术参考。 相似文献
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Shelf-mounted Ocean Thermal Energy Conversion (OTEC) plants require installation of cold-water pipes (CWP) on slopes of40deg to depths of 1000 m. In addition, tower platforms containing OTEC power systems may be located on lesser sloped terrain near shore and exposed to special environmental loading problems affecting foundation design. Shelf-mounted installations require careful attention to site selection and geotechnical considerations for foundation integrity on sloped surfaces. This paper primarily discusses research associated with cold-water pipe and foundation installations on steep slopes, although research continues on tower platforms located on the shelf. At least five nations are in various stages of development of OTEC systems for island applications. Each of their systems is either shelf mounted or land based and requires that a large diameter cold-water pipe be installed on a steep slope to provide cold water from 1000-m depths. In addition to the installation and deployment of the large cold-water pipe, the most significant problem is the design and installation of suitable foundations that will last for several decades. To date there is very little experience in the offshore industry for large installations on steep slopes. A major scale-model research project is underway on the slopes of the island of Hawaii. A section of pipe 2.4 m in diameter and 24 m long was installed using combination concrete foundations and joints. The pipe and foundations are fully instrumented to measure environmental loading forces due principally to currents and waves. Environmental measurements will also be taken in the test area. The measurement data will be used to validate available analytical models for subsequent use in aiding industry in providing more cost-effective designs for OTEC pipes and foundations. 相似文献
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To minimize cold water pipe lengths, the most favorable land or fixed platform based Ocean Thermal Energy Conversions (OTEC) sites have subbottom slopes greater than 5°. Observations at OTEC sites in Hawaii indicate that turbidity currents of an impulsive or episodic nature can occur with frontal speeds of several meters per second. Such speeds and the attendant potential for sediment transport and abrasion along routes containing OTEC installations indicate that the pertinent features of these flows are an important design criteria for OTEC or any other steep-slope marine installation. To satisfy this need, models of oceanic turbidity flows and similar flows have been examined. The model that addresses OTEC steep-slope conditions most succinctly was developed originally by Hopfinger and Tochon-Danguy (1977) for snow avalanches on land. This two-dimensional avalanche model is used to estimate the speed and growth characteristics of potential turbidity currents downslope for various postulated marine conditions of initial flow density, height, volume, and length at slopes from 5 to 60°. The areas of additional research required to increase reliability of the analyses are in the initiation and initial development of a turbidity plume, the mechanisms of sediment entrainment to and loss from the plume, and three-dimensional in addition to two-dimensional studies. 相似文献
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Chih Wu 《Ocean Engineering》1987,14(4)
Maximum power and efficiency at the maximum power of an irreversible OTEC heat engine are treated. When time is explicitly considered in the energy exchanges between the heat engine and its surroundings, it is found that there is a bound on the efficiency of the real OTEC heat engine at the maximum power condition. This bound can guide the evaluation of existing OTEC systems or influence design of future OTEC heat engines. 相似文献
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Fiber reinforced polymer composite deck panels are effectively used in the construction of offshore structures such as pontoons, floating docks, oil drilling platforms, ocean thermal energy conversion (OTEC) systems and harbor structures due to their excellent corrosion and fatigue resistance, high strength to weight ratio and stiffness to weight ratio and less maintenance cost. The main objective of this investigation is to study the load–deflection behavior of glass fiber reinforced polymer (GFRP) composite deck panels under static loading. Three prototype GFRP composite deck panels each with a size of 3000 mm×1000 mm×300 mm were fabricated using hand lay-up process and tested under a factored load of AASHTO HS20/IRC Class A wheeled vehicle. The deck panels were analyzed using the standard FE software, ANSYS. Maximum deflection and strain at factored load, and flexural and shear rigidities were calculated in the FE analysis and compared with the experimental data, and also with the specifications given by the Ohio Department of Transportation (ODOT), USA. From this study, it is concluded that the fabricated GFRP deck panels satisfied the performance criteria specified by ODOT and can be used in berthing structures, bridges in coastal regions, offshore oil platforms, OTEC systems and also in seismic prone areas. 相似文献
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海洋温差能资源时空分布特征分析和总量估算是其开发利用及选址、设计的基础工作。本文通过研究海洋温度场的变化特征,结合信息熵理论,应用高斯分布函数,建立了一种新的海洋温差能资源评估算法,即海洋温差熵(ocean temperature differences entropy, OTDE)算法,提出了表征温差时空变异特征的海洋温差熵作为评估参数,并结合中国南海海域开展了温差在不同时间尺度和空间范围上不确定性变化的定量研究。结果表明:中国南海榆亚暗沙、黄岩岛附近海域的海洋温差时空分布较稳定、资源可预测性强,是海洋温差能开发建址的理想区域,可为今后南海温差能资源评估及电站选址提供技术参考。 相似文献
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反渗透膜技术于20世纪60年代取得突破性进展,促使反渗透海水淡化在近50年间高速发展,淡化产能自20世纪90年代起激增.海水反渗透(SWRO)淡化已成为目前投资最省、成本最低的利用海水制备饮用水的过程.文中主要对海水反渗透淡化的发展状况进行了介绍,如膜和组件的改进,关键设备高压泵和能量回收装置效率的提高,多种工艺过程的不断发展,包括预处理和后处理的新工艺,以及对环境的影响和相应对策等.反渗透技术的发展也推动了其他膜分离技术的进步,并扩展其应用领域.预计在不久的将来,膜技术在海水淡化和水再利用、扩大和保护水资源、循环经济、清洁生产、改造传统产业、节能减排及提高人民生活水平等方面发挥的作用会越来越显著. 相似文献
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Owen M. Griffin 《Ocean Engineering》1981,8(2):129-209
Vortex-excited oscillations of marine structures result in reduced fatigue life, large hydrodynamic forces and induced stresses, and sometimes lead to structural damage and to destructive failures. The cold water pipe of an Ocean Thermal Energy Conversion (OTEC) plant is nominally a bluff, flexible cylinder with a large aspect ratio (L/D = length/diameter), and is likely to be susceptible to resonant vortex-excited oscillations. The objective of this paper is to survey recent results pertaining to the vortex-excited oscillations of structures in general and to consider the application of these findings to the design of the OTEC cold water pipe. Practical design calculations are given as examples throughout the various sections of the report.This paper is limited in scope to the problems of vortex shedding from bluff, flexible structures in steady currents and the resulting vortex-excited oscillations. The effects of flow non-uniformities, surface roughness of the cylinder, and inclination to the incident flow are considered in addition to the case of a smooth cylinder in a uniform stream. Emphasis is placed upon design procedures, hydrodynamic coefficients applicable in practice, and the specification of structural response parameters relevant to the OTEC cold water pipe. There are important problems associated with the shedding of vortices from cylinders in waves and from the combined action of waves and currents, but these complex fluid/structure interactions are not considered in this paper. 相似文献
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Grard C. Nihous 《Ocean Engineering》2007,34(17-18):2210-2221
An interhemispheric box model of the Atlantic thermohaline circulation (THC) is modified by replacing the tropical box with two vertically resolved sub-domains. Seawater flows from large-scale ocean thermal energy conversion (OTEC) are allowed in one of the tropical sub-domains. Under present conditions and standardized OTEC operations, steady-state net power production density would reach a maximum of about 80 kW/km2 (corresponding to 1.8 TW) with a cold seawater withdrawal per unit area of about 14 m/yr. This maximum reflects the impact of large OTEC flows on the oceanic thermal structure, although the THC would not be significantly affected. It is larger than a recently suggested worldwide value of the order of 30 kW/km2 because of the relative strength of the Atlantic THC. Under asymmetric high-latitude warming scenarios potentially representative of current climatic trends, a substantial weakening or a reversal of the THC are possible. In the former case, recoverable OTEC resources could practically vanish. In the latter case, the emergence of a stronger reverse THC eventually could boost OTEC resources. Such events are hypothetical and would unfold over centuries, but the mere possibility of their occurrence challenges the accepted notion that OTEC resources are forever renewable. 相似文献
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“薄散弱”油藏由于其油层薄、砂体小、分布零散、天然能量弱,采用定向井难以经济有效开发;采用水平井开发虽可提高单井初期产量,但由于地层能量不足,产量递减快,无法从根本上解决采收率低的问题;注水开发虽能解决地层能量不足问题,但海上注水要增加设备、平台空间及平台重量,相应地增加开发成本,加上其储量规模小,经济效益难以保证.以X油田H4油藏为例,在储层精细描述的基础上,提出并实践了多底多分支水平井技术与地层自流注水技术,实现了“薄散弱”油藏的经济有效开发,并取得了较好的开发效果.其实践成果对类似难动用储量的经济有效开发具有借鉴和参考意义. 相似文献
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海洋温差发电有机朗肯循环工质选择 总被引：3，自引：0，他引：3
为了筛选出适宜于海洋温差热力发电有机朗肯循环的工质.采用PR状态方程计算11种低沸点有机流体工质在闭式海洋温差有机朗肯循环中的热力性能.结果表明,随着工质临界温度升高,循环热效率总体呈上升趋势.正丁烷具有较高的循环热效率,其蒸发压力较低、凝汽压力比较适中,比较适合用作海洋温差发电有机朗肯循环的工质. 相似文献
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Chih Wu 《Ocean Engineering》1990,17(3)
The specific power of a simple irreversible closed-cycle OTEC power plant is analyzed and optimized. The plant uses a working fluid such as ammonia to produce power. Specific power is the net output per unit total heat exchanger surface area. Net output generated by the working fluid is obtained in terms of the rate of heat added to the working fluid from the warm surface ocean water, less the rate of heat removed from the working fluid to the cold deep ocean water. A time factor is added to iimulate the heat exchanges between the OTEC plant and its surroundings. A mathematical expression is derived for the specific power output of the irreversible OTEC heat engine. It is found that there is a bound on the specific power output. This bound provides the basis for a practical engineering effort towards maximizing the per unit time and per unit total heat exchanger area production of work in power plants whose heat transfer area is constrained by economic consideration. 相似文献
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This paper reviews the major challenges involved in reliable electric power delivery to remote deep water enhanced oil recovery (EOR) systems. As the oil well matures, top side based booster systems are not economical, and hence, subsea based booster systems are required. Such EOR processes require subsea systems to be operated at varying power and voltage levels, and this requires establishing subsea power stations with long tiebacks from the shore. Subsea stations carry out safe voltage step-down, distribution and conversion of electrical power in the order of mega watts. Breakdowns in subsea based EOR systems lead to huge production losses, and system retrieval for repair and maintenance is very costly and time consuming, and therefore systems need to be highly reliable. This paper describes the technical challenges involved in subsea variable speed motor drives, long step out power transmission, subsea energy storage requirements for safe start up and emergency shutdown, thermal and humidity management inside pressure rated enclosures, fault localization, pressure tolerant electronics and bio-fouling. Emerging advancements in electrical, power electronic, power transmission, energy storage and packaging technologies are reviewed, giving the confidence that the present technical maturity would be able to drive the development of reliable subsea based EOR systems. 相似文献
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Moving to open ocean locations will require the aquaculture industry to fundamentally change the way it develops installations due to increased environmental loads and longer distances from shore. With reference to the same technical issues faced by the oil producing offshore industry, technical and engineering challenges that are likely to face the aquaculture industry are identified with an emphasis on conditions off the east coast of Canada. Requirements are discussed with a view toward identifying areas where the aquaculture industry can borrow technology from the oil industry and areas where the Canadian aquaculture industry faces challenges unique to itself. 相似文献
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An investigation has been made of available data on the saturation state of seawater with respect to calcium carbonate and its possible significance for scale formation on Ocean Thermal Energy Conversion (OTEC) heat exchangers. Pertinent oceanographic data is lacking at or near potential OTEC sites for the calculation of the degree of saturation of seawater with respect to calcium carbonate. Consequently, only “extrapolated” saturation values can be used. These indicate that near surface seawater is probably supersaturated, with respect to the calcium carbonate phases calcite and aragonite, at all potential OTEC sites. The deep seawater that would be brought to the surface at the potential Atlantic Ocean sites is also likely to be supersaturated with respect to calcium carbonate. The deep seawater at the potential Pacific Ocean sites may be slightly undersaturated.The fact that OTEC heat exchangers will be operating in seawater, which is supersaturated with respect to calcium carbonate, means that if nucleation of calcite or aragonite occurs on the heat exchanger surfaces, significant growth rates of calcium carbonate scale may be expected. The potential for calcium carbonate nucleation is highest at cathodic metal surface locations, which are produced as the result of aluminum corrosion in seawater. Consequently, corrosion and scale formation may be closely related. What the possible effects of biofouling may be on this process are not known. 相似文献
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Timothy S. Collett Myung W. LeeWarren F. Agena John J. MillerKristen A. Lewis Margarita V. ZyrianovaRay Boswell Tanya L. Inks 《Marine and Petroleum Geology》2011,28(2):279-294
In the 1960s Russian scientists made what was then a bold assertion that gas hydrates should occur in abundance in nature. Since this early start, the scientific foundation has been built for the realization that gas hydrates are a global phenomenon, occurring in permafrost regions of the arctic and in deep water portions of most continental margins worldwide. In 1995, the U.S. Geological Survey made the first systematic assessment of the in-place natural gas hydrate resources of the United States. That study suggested that the amount of gas in the gas hydrate accumulations of northern Alaska probably exceeds the volume of known conventional gas resources on the North Slope. Researchers have long speculated that gas hydrates could eventually become a producible energy resource, yet technical and economic hurdles have historically made gas hydrate development a distant goal. This view began to change in recent years with the realization that this unconventional resource could be developed with existing conventional oil and gas production technology. One of the most significant developments was the completion of the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well on the Alaska North Slope, which along with the Mallik project in Canada, have for the first time allowed the rational assessment of gas hydrate production technology and concepts. Almost 40 years of gas hydrate research in northern Alaska has confirmed the occurrence of at least two large gas hydrate accumulations on the North Slope. We have also seen in Alaska the first ever assessment of how much gas could be technically recovered from gas hydrates. However, significant technical concerns need to be further resolved in order to assess the ultimate impact of gas hydrate energy resource development in northern Alaska. 相似文献
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Jonny Hesthammer Aristofanis Stefatos Mikhail Boulaenko Alexander Vereshagin Peter Gelting Torolf Wedberg Gregor Maxwell 《Marine and Petroleum Geology》2010
The use of the controlled source electromagnetic (CSEM) method as a risk reduction tool in marine hydrocarbon exploration is gaining increased acceptance in the oil industry. This is related to the ability to map resistivity contrasts in the sub-surface and thus aid the detection of hydrocarbons which are typically more resistive than surrounding rocks. Whereas acoustic (seismic) energy allows for mapping sub-surface structures that may contain hydrocarbons, electromagnetic (EM) energy can often say something about the fluids contained within the structures. Numerous successful CSEM case stories have been published over the past several years. However, there are also quite a few stories about “failure”-cases, although not well documented in the literature. Such “failure”-cases may reflect the lack of understanding of the CSEM technology and how CSEM data can act as a value driver. In order to understand this, it is necessary to handle uncertainties and decisions associated with the technology, These include geological uncertainties, noise models, survey designs, forward modelling parameters, inversion/migration parameters and pre-processing of real data. A proper handling of these uncertainties and decisions will aid in defining and constraining the chance of geologic success and geologic-success-case net present value for prospects prior to drilling wells. As such, the CSEM technology has a significant potential to increase exploration efficiency, if applied correctly. 相似文献