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1.
Fuel consumption in fisheries is a primary concern because of its effects on the environment and the costs incurred by fishermen. Many studies have been conducted to reduce the fuel consumption in fishing operations. Fuel consumption due to fishing gear during a fishing operation is generally related to the hydrodynamic resistance on the gear. This means that fuel consumption is proportional to the drag created by the towing speed. Based on numerical methods, this study suggests a new approach to reduce fuel consumption in fisheries. The results of the simulation are in good agreement with those of model experiments. The total as well as partial resistance forces on the gear are calculated by simulation. The simulation results suggest improved materials and gear structure for reducing the hydrodynamic forces on the gear while maintaining gear performance. The method for assessing the gear performance involves measuring the height and width of the net mouth. Furthermore, this study investigates the efficiency of a low-energy trawl from an economic point of view. The findings of this study will be useful in reducing greenhouse gas (GHG) emissions in fishing operations, and thereby contribute toward lowering fishing costs by saving fuel.  相似文献   

2.
CO2 emissions from international shipping, which are currently unregulated, are predicted to rise dramatically if no regulations are implemented. International bunker fuel emissions have been excluded from the Kyoto Protocol; the UNFCCC conference in Copenhagen also failed to bring about clear directions on how to proceed with these emissions.  相似文献   

3.
For over 5000 years, humans have successfully harnessed the power of wind to transport people and goods across the world's oceans. This research expands on previous studies of the unique Flettner rotor propulsion system and the demonstrable success in reducing fuel consumption and carbon dioxide (CO2) emissions. Recent examples such as Enercon's E-ship 1 have proven seaworthy and economically viable along major shipping routes. The remote Pacific island countries (PICS), however, have the unique characteristics of retaining a remarkable seafaring heritage while remaining on the periphery of global commerce. With data obtained from a field study of Fiji's domestic shipping, this research analyzes the potential for implementing Flettner rotor systems to achieve more economically viable alternatives to the current situation. The findings show that with an incremental approach and the addition of a government fuel savings incentive, the Government Shipping Franchise Scheme (GSFS) subsidies could be significantly lowered for Fiji's ten uneconomical shipping routes. Four scenarios of 5%, 10%, 15%, and 25% fuel savings contrast the baseline data on one extreme with a zero-emissions scenario on the other. The most likely fuel savings scenario of between 10% and 15% results in a 20-year government savings of between 348,042 and 522,063 U.S. dollars and a 20-year cumulative reduction in CO2 emissions of between 2931 and 4396 t. The paper concludes that Flettner rotors show promising results in reducing fuel consumption and CO2 emissions and recommends future studies in collaboration with the Fiji government to develop practical strategies of implementation.  相似文献   

4.
Low carbon shipping research focuses on energy efficiency and mitigation measures related to operations and technology. However, reducing energy use and greenhouse gas emissions associated with a vessel’s material production receives limited attention. Material efficiency is defined as “providing material services with less material production and processing”. The current business model for ship building and breaking does not embrace fully material efficiency principles. Exploring a case study of a vessel's steel hull, this study applies a Life Cycle Assessment approach to determine the effectiveness of material efficiency to reduce CO2 emissions. When compared to Business as Usual, designing and manufacturing for 100% hull reuse provides an emissions reduction of 29% from 221,978 t CO2 to 158,285 t CO2; 50% reuse provides a 10% reduction (199,816 t CO2). From a technical and safety perspective there remain key barriers that need addressing: a vessel’s hull would require to be designed for dismantling to improve reuse; the operation and maintenance schedule must ensure the value of the steel is retained and; data must flow between key stakeholders on the quality of the steel. Despite these challenges, progressing material efficiency would require different business models that reach out and integrate the whole supply chain. There is a need for public and privately funded demonstration projects at a range of scales and markets, to provide investors the confidence that there is retained value in the steel hull when it reaches its end-of-life.  相似文献   

5.
The shipping sector is required to reduce fuel sulphur content to 0.1% in Emission Control Areas by 2015 and to 0.5% globally by 2020. Although this is demanding, a greater challenge for all sectors is climate change. However, the three options to comply with sulphur regulation do little to address this challenge. With a deep-seated change to the type of fuel burnt in marine engines, this should be seen as an opportunity to explore co-benefits of sulphur and carbon reduction – instead of taking a short-sighted approach to the problem. It is argued here that the upcoming sulphur regulations should be postponed and instead, a co-ordinated suite of regulations should be implemented that tackles cumulative CO2 emissions and localised SOx emissions in chorus. This would ensure that less developed, yet more radical, step-change forms of propulsion such as wind, battery and biofuels are introduced from the outset – reducing the risks of infrastructure lock-in and preventing the lock-out of technologies that can meaningfully reduce absolute emissions from the sector.  相似文献   

6.
Diesel engines are used widely as the power sources of coastal ships and international vessels primarily due to their high thermal efficiency, high fuel economy and durable performance. However, the gaseous and solid substances exhausted from diesel engines during the combustion process cause air pollution, in particular around harbor regions. In order to effectively reduce particulate matter and gaseous pollution emissions, a catalyzed particulate filter was equipped in the tail pipe of a marine diesel engine. The engine's performance and emission characteristics under various engine speeds and torques were measured using a computerized engine data control and acquisition system accompanied with an engine dynamometer. The effectiveness of installing a catalyzed particulate filter on the reduction of pollutant emissions was examined. The experimental results show that the exhaust gas temperature, carbon monoxide and smoke opacity were reduced significantly upon installation of the particulate filter. In particular, larger conversion of carbon monoxide to carbon dioxide — and thus larger CO2 and lower CO emissions — were observed for the marine diesel engine equipped with a catalyzed particulate filter and operated at higher engine speeds. This is presumably due to enhancement of the catalytic oxidation reaction that results from an exhaust gas with stronger stirring motion passing through the filter. The absorption of partial heating energy from the exhaust gas by the physical structure of the particulate filter resulted in a reduction in the exhaust gas temperature. The particulate matter could be burnt to a greater extent due to the effect of the catalyst coated on the surface of the particulate filter. Moreover, the fuel consumption rate was increased slightly while the excess oxygen emission was somewhat decreased with the particulate filter.  相似文献   

7.
Biodiesel, which is manufactured from vegetables oils, animal fats, or algae can be an excellent alternative fuel to petroleum diesel due to its superior fuel properties and lower pollutant emissions. In contrast, fishing-boat fuel generally has much poorer fuel properties and a high sulfur content that can reach several hundred times that of the premium diesel used in land-based vehicles. Pollutant emissions from fishing boats are known to be a significant source of air pollution in the global environment. This study examines the use of biodiesel to replace fishing-boat fuel A to reduce pollutant emissions from fishing boats. The incremental cost, reduction in emissions, and cost-benefit corresponding to various weight proportions of biodiesel to replace fishing-boat fuel A are evaluated. The results show that the annual consumption of fishing-boat fuel A by Taiwanese fishing boats amounts to 649,201 kiloliters (kl) and total emissions from burning the fuel is 958.93 tons per year. If all fishing-boat fuel A were replaced with biodiesel, then pollutant emissions would be decreased by 421.94 tons, or 44.0%. However, this would also result in a USD 144.45 million or 25.85% increase in fuel cost. This study also finds that a replacing 20 wt% of fishing-boat fuel A with biodiesel has the highest cost-benefit ratio, which implies a larger reduction in emissions with a lower fuel cost increase, and is the most suitable option for fishing boats in Taiwan.  相似文献   

8.
Degraded diesel oils are commonly used in marine power plants to conform to the demands of shipowners for fuel economy. The burning of these marine fuel oils, which frequently contain various extents of oxides of iron, silicon, calcium, vanadium and potassium, such as Na2SO4, Fe2O3, SiO2, CaO, V2O5, etc., are susceptible to form much more complex compounds of either gaseous or solid phases. The release of these emissions to the environment may cause atmospheric pollution and a health hazard to human beings. Emulsification of a fuel oil with water to produce a micro-water-particles-dispersed-in-oil (W/O) emulsion has been considered as one of the promising techniques to improve combustion characteristics of low-grade marine oils and in turn effectively help to reduce the release of air pollutants. Marine fuel oil A, which approximates ASTM No. 2D oil was used as the test oil and the surfactant Span 80 was used to promote the affinity and integrating force between the components of the emulsion. An emulsifying/homogenizing machine was employed to stir the emulsion mixture of the marine oil, distilled water, surfactant Span 80 and sodium sulfate (Na2SO4) powder of 300 ppm. The mechanically blended emulsion mixture was injected, atomized and burned in an oil-fired furnace using an automatic burner. Burning gas composition, burning efficiency and gas temperature were measured and analyzed. Compared to neat marine diesel oil, W/O emulsions had higher combustion efficiencies, higher concentrations of O2 and SO2, while gas temperatures were lowered and CO and NOx production was reduced. The addition of sodium sulfate decreased combustion efficiency and NOx concentration and increased O2, CO, and SO2 concentrations.  相似文献   

9.
In traditional naval architecture design methodologies optimization of the hull and propeller are done in two separate phases. This sequential approach can lead to designs that have sub-optimal fuel consumption and, thus, higher operational costs. This work presents a method to optimize the propeller–hull system simultaneously in order to design a vessel to have minimal fuel consumption. The optimization uses a probabilistic mission profile, propeller–hull interaction, and engine information to determine the coupled system with minimum fuel cost over its operational life. The design approach is tested on a KCS SIMMAN container ship using B-series propeller data and is shown to reduce fuel consumption compared to an optimized traditional design approach.  相似文献   

10.
The carbon to nitrogen (C:N) stoichiometry of phytoplankton production varied significantly during the spring–summer bloom in the North Water Polynya (NOW), from April through July 1998. The molar ratio of particulate organic carbon (POC) to nitrogen (PON) production by phytoplankton (ΔPOC:ΔPON) increased from 5.8 during April through early June to 8.9 in late June and July. The molar dissolved inorganic carbon (DIC) to nitrate+nitrite (NO3) drawdown ratio (ΔDIC: ΔNO3) increased from 6.7 in April and May, to 11.9 in June (no estimate for July because of ice melting). The discrepancy between ΔPOC:ΔPON and ΔDIC:ΔNO3 was likely due to dissolved organic carbon (DOC) production. Increased ΔPOC:ΔPON of phytoplankton and surface water ΔDIC:ΔNO3 throughout the phytoplankton blooms resulted from changes in physical properties of the upper water column, such as reduced thickness of the surface mixed layer that exposed phytoplankton to increased photosynthetically available radiation (PAR), accompanied by NO3 depletion. This is expected to have significant effects on the cycling of carbon (C) and nitrogen (N) in pelagic ecosystems, as the increased C:N ratio of organic matter decreases its quality as substrate for grazers and microbial communities. Based on ΔPOC:ΔPON, the ratio of POC to chlorophyll a (Chl) production (ΔPOC:ΔChl) and the relationship between Chl yields and NO3 depletion, we estimate that 71±17% and 46±20% of the depleted NO3 went to PON production in the euphotic zone over the polynya from April to early June, and late June to July, respectively. The remaining NO3 was likely channelled to dissolved organic nitrogen (DON) and heterotrophic bacteria, which were not returned to the dissolved inorganic nitrogen (DIN) pool through recycling during the course of the study. Hence, the autotrophic production of organic N and its recycling by the microbial food web were not coupled temporally.  相似文献   

11.
The influence that megalopolises have on the atmospheric composition on regional and global scales is the subject of intense investigations; however, data on the emissions of pollutants used for such investigations are often insufficiently reliable. In this work the possibilities for diagnosing long-term changes in nitrogen oxide emissions in megalopolises are investigated based on a combined use of data from satellite measurements and modeling of the tropospheric nitrogen dioxide content. Primary emphasis is placed on analyzing possible situations when emission changes are of a nonlinear character. The proposed methodology includes an original method for the nonlinear approximation of changes in a physical quantity from a noised time series of its measurements. Changes in NO x emissions are investigated in 12 megalopolises of Europe and the Middle East in the period from 1996 to 2008. Statistically significant changes in NO x emissions are detected in five megalopolises (Baghdad, Madrid, Milan, Moscow, and Paris). By using three megalopolises (Madrid, Milan, and Paris) as an example, it is shown that a nonlinear approximation of NO x emission changes agrees better with independent ground-based measurements than an analogous linear approximation.  相似文献   

12.
A new fuel consumption monitoring system was set up for research purpose in order to evaluate the energy performance of fishing vessels under different operating conditions. The system has been tested on two semi-pelagic pair trawlers in the Adriatic Sea with an engine power of around 900 kW, and with length overall of around 30 m. Both vessels work with a gear of similar design and size, the differences between the two vessels are in the propeller design and the hull material: the first with a controllable pitch propeller (CPP) and a metal hull, the second with a fixed pitch propeller (FPP) and a wooden hull. The fuel monitoring system conceived at CNR-ISMAR Ancona (Italy) consists of two mass flow sensors, one multichannel recorder and one GPS data logger. The working time duration, the vessel speed, the total fuel consumption and the instant fuel rate were logged by the system. A typical commercial round trip for a semi-pelagic trawler consists of several fishing operations (steaming, trawling sailing, etc.). Fuel consumption rate and vessel speed data were used to identify energy performance under different vessel-operating conditions. The highest fuel demands were during the trawling (130 l/h at 4.4 kn) and the steaming (100–130 l/h at 11 kn) phases. Fuel savings of up to 15% could be obtained by reducing the navigation speed of half a knot.  相似文献   

13.
This study indicates that environmental policy interventions significantly influence the innovation processes for reducing the emissions of marine engine technology. Several different types of interventions have been important and the effect is not directly proportional to the strength or spatial coverage of the intervention. Despite its relative weakness, the MARPOL rule on NOx emissions has contributed to technology development. We also show that the rise of environmental issues in other fields has had a marked effect on the development of the marine sector and that relatively local interventions can influence innovation even in an international sector like marine transport.  相似文献   

14.
Concentrations of nutrients (NO3, NO2, Si(OH)4, PO4 and dissolved inorganic carbon (DIC) were measured in a series of seawater samples collected over approximately 15 months in 2005 and 2006 by an automatic water sampler (Remote Access Sampler, RAS) in the Northwestern North Pacific. Seasonal variability and concentrations of NO3 + NO2 (NOx and Si(OH)4 were comparable to previous shipboard observations, although there were small errors associated with measurements of PO4 and DIC. Concentrations of these nutrients began to decrease in late April. After the end of June, NOx and Si(OH)4 decreased rapidly, with large fluctuations. After October, these nutrients increased again until late spring 2006. The ratio of the decrease of Si(OH)4 to that of NOx suggests that numbers of biogenic opal-producing creatures, such as diatoms, increased after the end of June. This conclusion was supported by a rapid increase in biogenic opal flux recorded in a sediment trap at 150 m. The relationship between NOx concentrations at the RAS depth of 35 m and NOx integrated over the upper 100 m was determined using previous shipboard hydrocast data. This relationship was used to estimate integrated mixed layer NOx concentration from RAS data. Estimated new production based on seasonal drawdown of integrated NOx averaged approximately 156 mg-C m−2day−1 annually, which agrees with previous estimates. Thus, an automatic seawater sampler that documents annual maximum and minimum nutrient concentrations and episodic events such as storms and spring blooms, which might be missed by an ordinary research vessel, will contribute to time-series observations of nutrients and, by extension, biological pump activity.  相似文献   

15.
The spring diatom bloom characterizes the plankton and nutrient dynamics in the Oyashio region, the westernmost part of the subarctic Pacific. Previous studies have shown that NO3 was not depleted during the spring bloom, and an increase in the consumption ratio of Si(OH)4 to NO3 (ΔSi(OH)4:ΔNO3) was observed as the spring bloom progressed. The increase in ΔSi(OH)4:ΔNO3 has been suggested to be caused by growth stresses of diatoms, e.g. light limitation by self-shading. In the present study, incubation experiments of sea-surface water from the Oyashio region under saturated irradiance showed that NO3 was depleted first and ΔSi(OH)4:ΔNO3 was more or less constant until the NO3 depletion occurred. The increase in ΔSi(OH)4:ΔNO3 was observed after the NO3 depletion had occurred in contrast with the field observation. This result of the increase in ΔSi(OH)4:ΔNO3 under saturated irradiance after NO3 depletion suggests that the in situ increase in ΔSi(OH)4:ΔNO3 before the NO3 depletion might be caused by light limitation for diatoms. Responses to a reduction in irradiance were examined using diatom species isolated from the Oyashio region. Variable responses to a reduced irradiance were observed for cell specific C, N, Si and chlorophyll a (Chl) contents. However, the examined diatom species showed similar tendencies for increases in Si:C and Si:N and decreases in C:Chl ratios with the reduction in irradiance. We conclude that light limitation changes the uptake ratio of nutrients and the elemental composition of diatoms and that light limitation is one of the factors influencing the physiology of diatoms and nutrient dynamics in the Oyashio region during the spring bloom.  相似文献   

16.
浒苔对NH+4-N与NO-3-N吸收的相互作用   总被引：1，自引：0，他引：1  
在国内首次研究了大型海洋绿潮藻浒苔(Ulva prolifera)对NH4+-N与NO 3--N两种氮源的选择吸收作用。结果表明:当两种氮源等浓度比例存在时,随着NH4+-N与NO3--N浓度升高,藻体对NH4+-N的吸收速率逐渐升高,而对NO3--N吸收受到抑制;当NO3--N和NH 4+-N高浓度比存在时,藻体对NH4-N的吸收速率随着NO3--N/NH4+-N比例的升高和NH4-N浓度的下降而降低;当NO3--N和NH4+-N低浓度比存在时,藻体对NH+4-N保持较高的吸收速率,而对NO3--N的吸收效率随着NO3--N浓度的降低而降低;浒苔具有同时利用水体中较高浓度的NH+4-N和NO3--N的能力,只有当NH4+-N或NO3--N浓度较低时,才以吸收相对应的氮源为主。这说明浒苔能够快速、大量地吸收水体中氮源,为爆发性增殖贮备物质条件。同时,即便两种氮源同时存在,浒苔对NH+4-N的吸收速率也远高于对NO3--N的吸收速率,因此,控制NH4+-N的大量输入仍是预防浒苔绿潮爆发的关键。  相似文献   

17.
This article addresses the present status of seafood-oriented environmental methods and analyses, and pinpoints areas for further development. A recent study of the CO2 emissions associated with the production of farmed salmon in Norway, following the life cycle from hatching to consumption, is presented. The study was initiated due to the increased focus on environmental impacts from food production among consumer organizations, retailers, and authorities. In general, several methods are being currently applied to measure environmental performance. Unfortunately, different methods provide quite different results. An additional challenge is that most of these methods were originally developed for land-based production. If assumptions about the performance of the seafood industry are established on the basis of incorrect information, consequences for both the management and the market level may not be desirable.  相似文献   

18.
This paper investigates the properties of thickness extension mode excited by lateral electric field on LiNbO3 by using the extended Christoffel--Bechmann method. It finds that the lateral field excitation coupling factor for a-mode (quasi-extensional mode) reaches its maximum value of 28% on X-cut LiNbO3. The characteristics of a lateral field excitation device made of X-cut LiNbO3 have been investigated and the lateral field excitation device is used for the design of a high frequency ultrasonic transducer. The time and frequency domain pulse/echo response of the LiNbO3 lateral field excitation ultrasonic transducer is analysed with the modified Krimholtz--Leedom--Matthae model and tested using traditional pulse/echo method. A LiNbO3 lateral field excitation ultrasonic transducer with the centre frequency of 33.44 MHz and the --6 dB bandwidth of 33.8% is acquired, which is in good agreement with the results of the Krimholtz--Leedom--Matthae model. Further analysis suggests that the LiNbO3 lateral field excitation device has great potential in the design of broadband high frequency ultrasonic transducers.  相似文献   

19.
Carbon capture and storage (CCS) is one method to reduce CO2 emissions to the atmosphere. As CCS has the greatest potential for greenhouse gas (GHG) emission reduction, it gains a wide currency in the developed countries. However, the technology for CCS does not spread at the international level especially to the developing countries like South China Sea states. As the CO2 storage period is quite long and potential environmental risks involved, fully deployed CCS projects need not only the technological support but the appropriate legal and regulatory regime to safeguard CCS operations. This article offers a survey of CCS projects in the South China Sea region and discusses the legal challenges associated with CCS activities in state practice.  相似文献   

20.
南海大鹏湾盐田海域骨条藻数量的多元分析   总被引：15，自引：3，他引：15  
１９９０年及１９９１年３月３０日－５月３０日，在南海大鹏湾盐田海域设点测定骨条藻数量及各环境要素，以逐步回归，主成分分析及判别分析的方法，分析该海区骨条藻数量与环境因子的关系。１９９０年４、５月与１９９１年４，５月骨条藻数量差异与该期间环境因子值差异显著有关；初步提出用三维主成分分析图及判别分析方程作为盐田海域骨条材料潮预报的方法。  相似文献   

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