LNG as cold heat source in OTEC systems

Arcuri, Natale; Bruno, Roberto; Bevilacqua, Piero

doi:10.1016/j.oceaneng.2015.05.030

Cited by 32 publications

(19 citation statements)

References 28 publications

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“…The seawater is used to promote the ammonia vaporization and the LNG to support its condensation. These cycles allow for an increment of the produced electric power by recovering the LNG exergy and, at the same time, guarantying the LNG regasification for the supply of the gas pipeline network [7]. An OTEC plant operating with ammonia presents temperature and pressure values that are strongly different from those of a traditional OTEC Rankine cycles; therefore, the ammonia was chosen because it seems a suitable working fluid on the basis of the real operative conditions.…”

Section: Natural Gas Direct Expansion Techniquementioning

confidence: 99%

“…If the condensation pressure is set to 10 kPa, in the ammonia turbo-expander a mechanical work of 346 kJ/kg is producible, by reaching at the end of the process a temperature of about 202 K, ever greater than the LNG temperature stored in the tanks located in the terminal. By supposing a pinch point temperature difference of 10 K in the involved heat exchangers, the other thermodynamic parameters can be determined imposing a pressure drop in the condenser and the vaporizer equal to 3 and 5%, respectively, of the nominal pressure and an efficiency equal to 85% for the pumps and the turbo-expander [7]. …”

Section: Natural Gas Direct Expansion Techniquementioning

confidence: 99%

“…The efficiency of the top cycle is determined by considering the produced electrical power and the released thermal power supplies of the bottom cycle to produce additional electric power and to preheat the LNG in the regasification process. The remaining heat required to complete the regasification could be provided by seawater [7]. Table 2.…”

Section: Advances In Natural Gas Emerging Technologiesmentioning

confidence: 99%

“…Starting from this value, the ammonia flow rate requested by the Rankine top cycle can be determined with an energy balance of the R717 condenser [7]. Regarding the points shown in Figure 6, the ammonia flow rate is equal to:…”

Section: Preliminary Sizing Evaluationsmentioning

confidence: 99%

“…The global efficiency of the two cycles in cascade considers the additional mechanical work produced by the direct expansion of the natural gas and the supplementary heats required to complete the ammonia vaporization and for the natural gas postheating [7]. Point 3 is representative of the gasification process supplied solely by the ammonia condensation heat; therefore, the thermal power required to complete the phase change in a dedicated heat exchanger can be determined with the following relation:…”

Section: Preliminary Sizing Evaluationsmentioning

confidence: 99%

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Energy Recovery from the LNG Regasification Process

Bruno¹,

Bevilacqua²,

Arcuri³

2017

Advances in Natural Gas Emerging Technologies

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The global request of natural gas (NG) is continuously increasing, consequently also the regasification of liquefied natural gas (LNG) is becoming a process largely employed. Liquefied natural gas at a temperature of around 113 K at atmospheric pressure has to be regasified for its transportation by pipeline. The regasification process makes the LNG exergy available for various applications, particularly for the production of electrical energy. Different possibilities to exploit the thermal energy released during regasification are available. New plant configurations whose functioning does not constrain the processes of the regasification terminal are proposed. A possible solution is LNG exploitation as a cold source for ocean thermal energy conversion (OTEC) power plants. Electric energy can be produced also by the exploitation of heat released from hot sources, for instance, the condensation heat of power plants by means of consecutive thermodynamic cycles. The rational use of the cold source (LNG) allows the increment of electrical production and growth of the thermodynamic efficiency, with corresponding environmental benefits.Keywords: LNG regasification, exergy analysis, OTEC systems, thermodynamic analysis, ammonia IntroductionThe natural gas (NG) can be converted in liquefied natural gas (LNG) in order to make easier its storage and transport. The exact composition of natural gas, and the LNG formed from it, varies according to its source and processing history; usually a percentage ranging from 85 to 95 is represented by pure methane. By cooling the natural gas to about 113 K (À160 C), it condenses into LNG, with a correspondent volume reduction factor of 600. In function of the © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.LNG ship capacity, the carried gas could be enough to heat almost 43,000 homes per year [1]. From an energy point of view, in fact, the LNG energy content is equal to about 50 MJ/kg, corresponding to 21.5 GJ/m 3 by considering that at 113 K, the mass is 430-450 kg m À3. Moreover, the regasified methane has a mass of about 0.71 kg m À3 in normal conditions, and its energy content is about 35 MJ/m 3 . LNG is usually transported by ship to dedicated terminals and then stored at atmospheric pressure in superinsulated tanks; successively, LNG is heated and converted into gaseous form in order to supply the pipeline system.From a historical point of view, the first regasification process operating with LNG began operation in 1917 in West Virginia, in order to produce stockpile helium as part of a research program. The first commercial plant, instead, was built in 1941 for peak-shaving purposes, by exploiting the stored liquefied natural gas as a strategic reservoir for future usage. The first LNG ship has left the Louisiana for the Unite...

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Section: Natural Gas Direct Expansion Techniquementioning

confidence: 99%

Section: Natural Gas Direct Expansion Techniquementioning

confidence: 99%

Section: Advances In Natural Gas Emerging Technologiesmentioning

confidence: 99%

Section: Preliminary Sizing Evaluationsmentioning

confidence: 99%

Section: Preliminary Sizing Evaluationsmentioning

confidence: 99%

See 3 more Smart Citations

Energy Recovery from the LNG Regasification Process

Bruno¹,

Bevilacqua²,

Arcuri³

2017

Advances in Natural Gas Emerging Technologies

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Reliability assessment of the ocean thermal energy conversion systems through Monte Carlo simulation considering outside temperature variation

Ghaedi,

Sedaghati,

Mahmoudian

et al. 2023

J Mar Sci Technol

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The ocean thermal energy conversion (OTEC) systems, as renewable energy-based power plants, have the potential to play a significant role in meeting future electricity demands due to the vast expanse of the world's oceans. These systems employ the temperature difference between surface ocean waters and deep ocean waters to drive a thermodynamic cycle and produce electricity. The temperature of deep ocean waters, approximately 1000 m below the surface, is approximately 4 °C, while surface ocean temperatures typically range between 20 and 30 °C. The generated power of OTEC systems is dependent on these temperature differences and may vary with changes in surface ocean temperatures. In this study, the main focus is to find the impact of temperature variation on the failure rates of OTEC system components and the generated power output of these plants. The findings indicate that as the demand for the power system increases, its reliability decreases. In order to improve the reliability of the power system, the integration of a new generation unit, such as the close cycle OTEC power plant under investigation, could be necessary. The findings also indicate the importance of considering temperature variation in the evaluation of the reliability of such types of power plants based on renewable energy.

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