Ocean-going Tankers Research Articles

Gaseous and particulate pollutant emissions from ocean-going tankers in the context of carbon reduction: Main engine, auxiliary engine, and auxiliary boiler

Ships are a major source of air pollution, which significantly impacts global health. In this study, the gaseous and particulate emissions from the main engine, auxiliary engine, and auxiliary boiler of a modern Tier Ⅲ large ocean-going vessel fueled with marine gas oil and heavy fuel oil have been investigated. Emissions of gaseous pollutants in the exhaust were measured online and particulate samples were collected to determine detailed physical and chemical properties. The results indicated that CO2 and NOx are the main gaseous pollutants, while organic carbon accounts for the majority of particulate pollutants for the three devices. The element carbon emissions of the auxiliary engine decreased with load increasing while those of the main engine maintained a level of approximately 0.062 g/kWh. The black carbon emissions of the main and auxiliary engine resulting from using marine gas oil were higher than heavy fuel oil. Consistent correlations among pollutants were observed for the engines. Finally, the measured value of element carbon cannot be utilized as a substitute for black carbon emissions due to the presence of light-absorbing organic carbon in organic carbon.

Numerical simulation of KVLCC2 self-propulsion with ducted propeller in head waves

In order to meet the Energy Efficiency Design Index (EEDI) requirements, consideration of reducing added power in waves is important for large tankers operating in ocean environments. In this study, the Reynolds-averaged Navier-Stokes (RANS) solver is employed in Computational Fluid Dynamics (CFD) method to simulate the self-propulsion of KVLCC2 model with a ducted KP458 propeller in head waves, especially for comparison with the non-ducted cases. Two methods are adopted for simulating the ducted propeller: the discretized propeller method and the improved body force ducted propeller method. The latter method incorporates an improved principle of momentum conservation to solve the advance speed of the ducted virtual disk precisely in real time, resulting in similar accuracy and higher efficiency compared to the former method. For some wavelengths, the ducted cases display higher propulsive efficiency and lower power than the non-ducted cases, especially under very short wavelength condition, where negative thrust deduction fraction is observed in the ducted case. With the increase of wave height, the effect of the duct becomes more pronounced, resulting in an increase in propulsive efficiency and a reduction in power, both of which can exceed 10%. Moreover, this research carefully analyzes the added values of self-propulsion factors in head waves, as well as flow fields, providing useful insights to inform the application of ducted propellers in ultra-large ocean-going tankers.

Waste heat recovery steam systems techno-economic and environmental investigation for ocean-going vessels considering actual operating profiles

Waste heat recovery steam systems is a proven technology for improving the ship power plant efficiency and reducing the ship environmental footprint, thus their usage can respond to the pressure for decarbonising the shipping operations. This study aims at investigating the techno-economic feasibility of various waste heat recovery steam systems whilst assessing their environmental impact for three ocean-going tanker vessels with their type spanning from Handymax size to very large crude carriers. Thermodynamic modelling of the investigated systems is employed for estimating the systems performance parameters including the generated electric power and fuel savings taking into account the vessels actual operating profiles and typical annual voyages characteristics. The systems net present value and the profitability index indicators are employed for assessing the systems economic feasibility, whereas the systems environmental impact is evaluated by using the achieved annual carbon dioxide emissions reduction. Two different nominal turbo-generator sizes matching the ship main engine full-load and part-load conditions are investigated, whereas a sensitivity analysis on the fuels prices is carried out to identify the marginal fuel price that renders the investment of each investigated system profitable. The derived results demonstrate that the single pressure waste heat recovery system sized for the ship engine part-load operation provides an attractive solution depending on the vessel type considering the technical, economic and environmental parameters. This study results in better insights on the impacts of the investigated energy efficiency improvement technologies for tanker ships, thus it can prove useful support for designing future sustainable ship power plants.

A Comparative Analysis of EEDI Versus Lifetime CO2 Emissions

The Energy Efficiency Design Index (EEDI) was introduced as a regulatory tool employed at the ship design phase to reduce the carbon dioxide (CO2) emissions and increase the vessel’s operational efficiency. Although it stimulated the greening of the shipping operations, its effectiveness is considerably criticised from various shipping industry stakeholders. The aim of this study is to investigate the EEDI effectiveness on accurately representing the environmental performance of the next-generation ships power plants for two representative ship types, in specific, an ocean-going tanker and a cruise ship. The performance of the optimal power plant solutions identified in previous studies is analysed according to the existing EEDI regulatory framework and compared with the lifetime CO2 emissions estimated based on an actual operating profile for each ship. The results indicate that the EEDI underestimates the effect of technologies for reducing carbon emissions in all the investigated cases. In this respect, it is concluded that EEDI is classified as a conservative metric, which however can be used as an approximation to compare alternative solutions early in the design phase.

OIL SPILL TRAJECTORY AND FATE FORECASTING, RESPONSE AND CLEANUP OPTIONS FOR A COASTAL ENVIRONMENT: A GREEN FIELD MODEL OFFSHORE INDONESIA

The environmental impacts of an oil spill and the attendant response applied for ecological restoration would mostly depend on the conditions of the spill, nature of the area, quantity and type of oil released, meteorological and climatological factors, as well as the effectiveness of response techniques. The Indonesian government and operators have been considering best ways of shielding the environment and their reputation from spill hazards, in cognizance of the region's high sensitivity and vulnerability. This paper thus undertakes a risk assessment for the potential environmental effects of possible spillage of medium light crude pumped to the Floating Storage and Offloading (FSO) terminal installed to handle production and bulk distribution of oil produced from a green oilfield offshore Indonesia. GNOME and ADIOS were deployed to forecast the trajectory and fate of oil spilled from the FSO during loading operations to ocean-going tankers, respectively. Key environmental data obtained from ESI maps were built into the models to yield desired results. The likely trajectory of oil released from the FSO as depicted by GNOME results for nine days after the spill and the contact probabilities show that 5,200 barrels of the oil would beach on the ninth day. Response efforts must thus be effected before this occurs. The results from ADIOS were captured for both winter and summer conditions; indicating that more spilled oil would remain after a 5-day period, if it occurs during winter, than would be obtained for a spill during summer. This implies less complicated cleanup operations in summer than in winter. However, since the oil is medium light, the lighter fractions would readily evaporate out, leaving behind heavier oily residues that may form tar balls with the submarine sediments and sink to the sea bottom or arrive at the beach, as shown by GNOME. Subsequent Net Environmental Benefits Analysis suggests that dispersants would not be a good response option due to their toxicity to the ecologically sensitive ecosystem. It is thus recommended to contain imminent spills using dykes and booms within a few hours of occurrence, before further dispersion and beaching. Subsequent in-situ burning would then enable all the hydrocarbons and most other contaminants present to burn off, thus protecting the shoreline and submarine resources. The study will guide spill responders and serve as a basis for future oil spill contingency plans (OSCPs) in the field and others within the Southeast Asian hydrocarbon provinces.

An interactive, computer-aided ship scheduling system

This paper is concerned with a fleet scheduling and inventory resupply problem faced by an international chemical operation. The firm uses a fleet of small ocean-going tankers to deliver bulk fluid to warehouses all over the world. The scheduling problem centers around decisions on routes, arrival/departure times, and inventory replenishment quantities. An interactive computer system was developed and implemented at the firm, and was successfully used to address daily scheduling issues as well as longer range planning problems. The purpose of this paper is to first present how the underlying decision problem was analyzed using both a network flow model and a mixed integer programming model, and then to describe the components of the decision support system developed to generate schedules. The use of the system in various decision making applications is also described.

LNG and world energy needs. Part 1: Gas liquefaction and world resources

The development of international trans-shipment of LNG will be reviewed, comparing the present achievement with the world potential. The scope for further development will be discussed together with the problems that delay it. Base-load liquefaction plants have already achieved a high level of efficiency and reliability, and the possibility of major improvement has become small. Present technical interest centres on the practicability of offshore liquefaction, including the problems of liquefaction on a floating barge, floating storage and flexible pipeline systems for LNG transfers. Land-based LNG storage systems have developed greatly, especially in Japan, where important strides have also been made in utilising the ‘cold’ available from re-evaporation. Whilst significant developments have been made with both above-ground and in-ground storage the present preferences appear to lie with a compromise solution involving an insulated tank partially submerged in the ground, the excavated earth being mounded around the tank up to the level of the tank top. There are now fleets of ocean-going tankers for LNG, and a few are laid-up awaiting charter. The largest has a capacity in excess of 130 000 m 3. Several different insulation systems are employed, the criteria being cost, evaporation losses and safety. Much attention is being devoted to the elimination of hazards which could arise with shipping accidents. Other uses of LNG are relevant to energy conservation on a smaller scale. These include peak-shaving plants, the enrichment of lean natural gas, satellite stations and diurnal storage.

The Trans-Alaska Pipeline Story

A group of seven oil companies has formed the Alyeska Pipeline Service Company to design, construct, operate and maintain the trans-Alaska pipeline system. The total pipeline will be approximately 789 miles long, some 641 miles of which will be across federal lands. The project will include pump stations, camp sites for use during construction, airfields for use during both construction and operation of the line, a communications system, and material sites for construction and access roads. The terminal site at Valdez will consist of a tank farm and dock facilities from which ocean-going tankers will transport crude oil to markets. A road will be built for access and the movement of equipment, materials, and personnel during pipeline construction activity, of approximately 373 miles in length. Of the approximately 586,000 sq miles of land in Alaska, the project will utilize about 0.01% of the total.

Trends in LACT Equipment Design and Application

Abstract During a relatively short period of six years, the method of lease automatic custody transfer (LACT) gained universal acceptance, and its use has grown from year to year at a very fast rate. This testifies to the value of the method to both the producing and the transportation branches of the industry. The design of LACT units has undergone considerable evolution during this period with the resulting simplification of the units and the consequent reduction in their investment and maintenance costs. The main economic advantage of LACT is the fact that it made possible the present accelerated trend toward consolidation of field oil-storage facilities, with the resulting substantial savings in operating costs. Particularly promising is the arrangement under which the untreated fluids from leases with different royalty accounts are metered and sampled at the individual leases, and are then commingled and brought to one central treating and LACT facility. While this arrangement at present is limited primarily to unitized fields or to cases where one company owns the whole field or a large portion of the field, there is no reason why it should not find its eventual application also in fields with diversified lease ownership through agreements between the operators for cooperative surface handling of oil. Introduction Few of the methods used in oilfield operations have gained such a universal acceptance in such a short period of time as the method of lease automatic custody transfer (LACT). The fact is even more remarkable when one considers the many interests which are involved in the transactions covered by this method. When the producer decides to introduce an innovation in the equipment he uses or in his operating practices, he is dealing with his own equipment and with oil which is under his exclusive custody. The same is true of the pipeline carrier when he decides to employ advanced methods in the operation of his system. However, at the point where the custody of oil is transferred from the producer to the pipeline (or to use a generally accepted although incorrect expression, where the oil is "sold" by the producer to the pipeline), there are many interests involved.The producer wants to be sure that he is paid for every barrel of oil which is transferred to the pipeline.The pipeline carrier wants to be assured that he receives the same amount of oil of the same quality as that which he will transfer to the buyer at the other end of his pipeline system.The royalty owner wants to be assured that he will receive his share of all the oil produced.The state regulatory bodies, if proration is involved, use transfer of custody records for a check on the compliance with lease-allowable restrictions.The tax authorities are using these records for determination of taxes. Because of this fact, there was a doubt in the minds of some (even among those who pioneered the LACT idea) regarding the acceptance of the method by the industry in place of the time-tested conventional methods of custody transfer. Actual facts exceeded all expectations. In a relatively short period of six years from the time the first official transfer of custody was made, the number of barrels of oil handled every day by LACT installations has been increasing at an extremely rapid rate, and all factors indicate that this trend will continue. This is the best proof that the basic idea of LACT is sound, and that it has benefited both the producing and the transportation branches of the oil industry. Definition of LACT and ACT A certain degree of misunderstanding seems to exist regarding the meaning of the expression, "lease automatic custody transfer". Even some of the oil companies using the method and some of the technical and trade publications refer to it sometimes as "ACT, automatic custody transfer". Because there is a basic difference between ACT and LACT and because the latter alone is the subject of this paper, it would be well to start with a clear definition of the method."ACT", automatic custody transfer, has been used for many years by the transportation, refining and marketing branches of the oil industry in transactions which did not involve the producer. For instance, the method has been and is being used for unattended transfer of custody of crude oil from one pipeline carrier to another, from pipeline carrier to the buyer, in loading of ocean-going tankers, in handling of products from refineries to the marketers and among the marketers. In contrast to this, "LACT" specifically covers the transfer of custody from the producer to the pipeline. JPT P. 1183^