As recently as 2008 liquefied natural gas (LNG) import facilities were being constructed in the United States in order to help meet domestic demand. Within the past five years, the development of hydraulic fracturing has created a seismic shift in the energy landscape as companies are turning their focus to exporting LNG instead of importing it. Today, there are currently more than twenty liquefaction facilities awaiting regulatory approval to export domestic product to non-Free Trade Agreement nations. As of November 2013, regulators have approved export capacity of approximately 2,300 billion cubic feet per year, a figure which could rise dramatically over the next decade. Clearly the shale revolution, which has suppressed domestic natural gas prices relative to European and Asian markets, has created an intriguing arbitrage opportunity. The risks to LNG asset owners, however, are high. Long-term domestic and regional prices are uncertain, and capital expenditure costs require a heavy debt burden. We will examine two primary LNG contract structures with altering project financing considerations. The first is the merchant model, in which the LNG asset owner takes title to the supply. The second is the tolling model, in which the LNG asset owner does not take title to the supply. Each of these scenarios will be valued using a high debt, low equity capital structure and a medium debt, medium equity capital structure. Once we have determined the relative valuations of each scenario, sensitivity analysis and Monte Carlo methods will be applied to the outcomes in order to determine the optimal combination of contract structure and capital structure for both debt and equity holders. / text

Denna studie bestod i att undersöka situationen på marknaden angående framdriftsanläggningar för LNG-tankfartyg. Syftet med arbetet var att skapa en relevant bild av hur situationen ser ut idag och genom intervjuer ta reda på hur den kan komma att förändras. Genom en litteraturstudie undersöktes läget på marknaden och utifrån det kunde relevanta frågor utformas. Efter att frågorna hade utformats tog författarna kontakt med olika företag som var anknutna till marknaden för LNG-tankfartyg. Intervjuer med företagen genomfördes och dessa har gjort det möjligt att analysera hur läget kan komma att förändras. Studien har visat att det finns ett system, DFDE, som dominerar fartygsbeställningar i dagsläget. Det finns även nyare system som består av gasdrivna tvåtaktsmotorer som förväntas ta över en del av marknaden. Andra system såsom ånganläggningar och anläggningar med gasturbin finns tillgängliga men de ligger inte i fokus i dagsläget. / This study consisted of analysing the current situation on the market for propulsion systems for LNG-carriers. The purpose of the study was to create a relevant picture of what the situation looks like today and through interviews try to predict how the situation might come to change. By using already existing literature the authors reviewed the situation on the market as it is today and formed relevant questions. After the questions had been formed the authors contacted several companies associated with the LNG-carrier market. Interviews with these companies were carried out and it is through these interviews possible to analyse how the situation might come to change. The study has shown that there is one system that dominates the market for LNG-carrier propulsion, DFDE. There is however a new system, with dual-fuel two stroke engines that is expected to take over a part of the market in the near future. Other propulsion systems such as steam propulsion plant and a system with a gas turbine exist on the market but the interest in these systems is limited.

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This research study investigated a new conceptual design for a modular structural configuration incorporating storage for Liquefied Natural Gas (LNG) within the base of the platform structure. The structure, referred to as a modified gravity base concrete structure (MGBCS), was envisioned specifically to be constructed at a suitable site off the coast of Kuwait. Coastal offshore bathometric information, environmental data and existing data on onshore facilities were examined in the site selection portion of the study. A finite element model of the MGBCS was developed using an industry standard finite element code that allows preliminary sizes of structural models to meet appropriate design codes. A variety of parametric and design load scenarios were investigated. This research tackles some preliminary issues that are adequate for an initial evaluation of the proposed design concept. The proposed design concept needs a lot more scrutiny in order to be sufficiently developed as a concept where it can be confirmed as a truly viable concept and investment. It was confirmed that quartering sea conditions, waves approaching at a 45 degree angle, are the most critical scenarios for the terminal based on maximum values and ranges of shears and moments. In addition, there are several interesting issues in this concept that should be further looked at for this design to be further developed. The limitations of our study must be mitigated in future designs if the proposed design concept is to be carried to the implementation stage.

The increased demand for liquefied natural gas (LNG) has led to the construction of several new LNG terminals in the United States (US) and around the world. To ensure the safety of the public, consequence modeling is used to estimate the exclusion distances. The purpose of having these exclusion distances is to protect the public from being reached by flammable vapors during a release. For LNG industry, the exclusion zones are determined by the half lower flammability limits (half LFL, 2.5% V/V). Since LNG vapors are heavier‐than‐air when released into atmosphere, it goes through stages, negative, neutral and positive buoyant effect. In this process, it may reach the half LFL. The primary objective of this dissertation is to advance the status of LNG vapor dispersion modeling, especially for complex scenarios (i.e. including obstacle effects). The most used software, box models, cannot assess these complex scenarios. Box models simulate the vapor in a free‐obstacle environment. Due to the advancement in computing, this conservative approach has become questionable. New codes as computational fluid dynamics (CFD) have been proven viable and more efficient than box models. The use of such advance tool in consequence modeling requires the refinement of some of the parameters. In these dissertation, these parameters were identified and refine through a series of field tests at the Brayton Firefighter Training Field (BFTF) as part of the Texas A&M University System (TAMUS). A total of five tests contributed to this dissertation, which three of them were designed and executed by the LNG team of the Mary Kay O'Connor Process Safety Center (MKOPSC) and the financial support from BP Global SPU Gas (BP). The data collected were used as calibration for a commercial CFD code called CFX from ANSYS. Once the CFD code was tuned, it was used in a sensitivity analysis to assess the effects of parameters in the LFL distance and the concentration levels. The dissertation discusses also the validity range for the key parameters.

Liquefied Natural Gas (LNG) hazards include LNG flammable vapor dispersion and LNG pool fire thermal radiation. A large LNG pool fire emits high thermal radiation thus preventing fire fighters from approaching and extinguishing the fire. One of the strategies used in the LNG industry and recommended by federal regulation National Fire Protection Association (NFPA) 59A is to use expansion foam to suppress LNG vapors and to control LNG fire by reducing the fire size. In its application, expansion foam effectiveness heavily depends on application rate, generator location, and LNG containment pit design. Complicated phenomena involved and previous studies have not completely filled the gaps increases the needs for LNG field experiments involving expansion foam. In addition, alternative LNG vapor dispersion and pool fire suppression methodology, Foamglas® pool fire suppression (PFS), is investigated as well. This dissertation details the research and experiment development. Results regarding important phenomena are presented and discussed. Foamglas® PFS effectiveness is described. Recommendations for advancing current guidelines in LNG vapor dispersion and pool fire suppression methods are developed. The gaps are presented as the future work and recommendation on how to do the experiment better in the future. This will benefit LNG industries to enhance its safety system and to make LNG facilities safer.

Natural gas has been considered a clean energy which is more environmental friendly and with higher combustion efficiency. In Taiwan, most LNG was imported from abroad, with large amount of cold energy for application, despite the fact that it has been utilized for only 8% of total. In LNG cold energy utilization process, the change of exergy can be simulated with the second law of Thermodynamics as a means to analyze its energy efficiency. Especially, when the transportation distance is long, the optimal insulation thickness can then be calculated to justify its economic feasibility. In this study, thermoeconomics was applied to analyze the feasibility of LNG cold energy recovery, which warrants it as a powerful design tool in engineering applications.

Liquefied Natural Gas (LNG) is becoming an increasing factor in the U.S. natural gas market. For 30 years LNG imports into the U.S. have remained fairly flat. There are currently 18 permit applications being filed in the U.S. and another 10 permit applications being filed in Canada and Mexico for LNG import terminals. The EIA (Energy Information Agency) estimates by 2025 that LNG will make up 21% of the total U.S. Natural Gas Supply. This study developed a neural network approach to forecast LNG imports into the U.S. Various input variables were gathered, organized into groups based on similarity, and then a correlation matrix was generated to screen out redundant variables. Since a limited number of data points were available I used a restricted number of input variables. Based on this restriction, I grouped the input variables into four different scenarios and then generated a forecast for each scenario. These four different scenarios were the $/MMBTU model, natural gas energy consumption model, natural gas consumption model and the energy stack model. The standard neural network approach was also used to screen the input variables. First, a correlation matrix determined which variables had a high correlation with the output, U.S. LNG imports. The ten most correlated input variables were then put into correlation matrix to determine if there were any redundant variables. Due to the lack of data points only the five most highly correlated input variables were used in the neural network simulation. A number of interesting results were obtained from this study. The energy stack model and the consumption of natural gas forecasted a non-linear trend in U.S. LNG imports, compared to the linear trend forecasted by the EIA. The energy stack model and consumption of natural gas model predicted that in 2025 U.S. LNG imports will be about 6.5 TCF, while the other three models prediction is about three times as less. The energy stack model is the most realistic model due its non-linear trend, when the rapid increase of LNG imports is going to occur, and the quantity of U.S. LNG imports predicted in 2025.

This research study investigated a new conceptual design for a modular structural configuration incorporating storage for Liquefied Natural Gas (LNG) within the base of the platform structure. The structure, referred to as a modified gravity base concrete structure (MGBCS), was envisioned specifically to be constructed at a suitable site off the coast of Kuwait. Coastal offshore bathometric information, environmental data and existing data on onshore facilities were examined in the site selection portion of the study. A finite element model of the MGBCS was developed using an industry standard finite element code that allows preliminary sizes of structural models to meet appropriate design codes. A variety of parametric and design load scenarios were investigated. This research tackles some preliminary issues that are adequate for an initial evaluation of the proposed design concept. The proposed design concept needs a lot more scrutiny in order to be sufficiently developed as a concept where it can be confirmed as a truly viable concept and investment. It was confirmed that quartering sea conditions, waves approaching at a 45 degree angle, are the most critical scenarios for the terminal based on maximum values and ranges of shears and moments. In addition, there are several interesting issues in this concept that should be further looked at for this design to be further developed. The limitations of our study must be mitigated in future designs if the proposed design concept is to be carried to the implementation stage.

The coupling and interactions between ship motion and inner-tank sloshing are investigated by a potential-viscous hybrid method in time domain. For the time domain simulation of vessel motion, the hydrodynamic coefficients and wave forces are obtained by a potential-theory-based 3D diffraction/radiation panel program in frequency domain. Then, the corresponding simulations of motions in time domain are carried out using the convolution-integral method. The liquid sloshing in a tank is simulated in time domain by a Navier-Stokes solver. A finite difference method with SURF scheme, assuming a singlevalued free surface profile, is applied for the direct simulation of liquid sloshing. The computed sloshing forces and moments are then applied as external excitations to the ship motion. The calculated ship motion is in turn inputted as the excitation for liquid sloshing, which is repeated for the ensuing time steps. For comparison, linear inner-fluid motion was calculated using a 3D panel program and it is coupled with the vessel motion program in the frequency domain. The developed computer programs are applied to a barge-type FPSO hull equipped with two partially filled tanks. The time domain simulation results show reasonably good agreement when compared with MARIN's experimental results. The frequency domain results qualitatively reproduce the trend of coupling effects but the peaks are usually over-predicted. It is seen that the coupling effects on roll motions appreciably change with filling level. The most pronounced coupling effects on roll motions are the shift or split of peak frequencies. The pitch motions are much less influenced by the inner-fluid motion compared to roll motions. A developed program is also applied to a more realistic offloading configuration where a LNG-carrier is moored with a floating terminal in a side-by-side configuration. First, a hydrodynamic interaction problem between two bodies is solved successfully in frequency and time domain. A realistic mooring system, including fender, hawser, and simplified mooring system, is also developed to calculate the nonlinear behavior of two bodies in time domain simulation. Then, the LNG-carrier and sloshing problem are coupled in frequency and time domain, similar to the method in the MARIN-FPSO case. Sloshing effect on LNG-carrier motion is investigated with respect to different tank filling levels including various conditions such as gap distance between two bodies, selection of dolphin mooring system, and different cases of environmental conditions using wave, wind, and current.