Pontoon Type Research Articles

Volatile organic compounds (VOCs) emissions from internal floating-roof tank in oil depots in Beijing: Influencing factors and emission reduction strategies analysis

The internal floating-roof tank is the main type of storage tank for refined oil products. The volatile organic compounds (VOCs) emission from the internal floating-roof tank plays a dominant role in the unorganized emission source of the oil depot. In this study, we selected six typical oil depots in Beijing to investigate VOC emission characteristics from the tank top vent hole using infrared imaging technology and flame ionization detector (FID). The results reveal that infrared thermal imager is efficient in quickly identifying the emission level of the tank discharge point. The ambient temperature and wind speed have a direct effect on sealing loss, the turnover can greatly influence the wall hanging loss, and the concentration of VOCs emitted from the tank top vent hole is negatively correlated with liquid height. Furthermore, the influence of accessories type of the internal floating-roof tank on the concentration of VOCs emission from the top vent hole is also studied when other parameters remain unchanged, and find the floating deck type and sealing mode have a significant influence on their VOCs emissions, of which the combination of pontoon type floating deck and secondary seal are effective in controlling the concentration of VOCs emitted from the tank top vent hole. Finally, based on our experimental results, several feasible emission reduction strategies are proposed in terms of source prevention and process control in order to achieve the fine management of the whole process. This paper provides important technical support and policy thoughts for VOCs emission control during oil storage.

Development of compliant modular floating photovoltaic farm for coastal conditions

Floating photovoltaic (PV) farms can be constructed in coastal marine conditions for the abundant ocean space compared to reservoirs. New challenges may arise when extending existing designs of reservoir floating PV farms to coastal regions because of the complex environmental conditions, especially for the pontoon type floating PV systems. This study presents the methodologies for the design and verification of such floating PV farms based on the practical example of one of the world's largest nearshore floating photovoltaic farms off Woodlands in Singapore. This 5 MW pilot project aims to move floating PV farms from inland water to nearshore regions for future larger-scale deployments. The innovative floating system is adapted from the successful modular floating PV development at Tengeh Reservoir and improved to withstand harsher marine environmental conditions. This study comprehensively introduces various aspects of the development of the nearshore floating modular PV farm, including its design, verification via full-scale experimental testing and numerical studies, construction, and power generation performances. The floating PV system comprises standardized floating modules made of high-density polyethylene (HDPE) that support PV panels or operational and maintenance work. A compliant design allows the floating system to follow wave motion. A verification study was conducted through full-scale experimental tests and numerical simulations based on a representative subsystem of the floating PV farm, focusing on its hydrodynamic performance. Finally, this study presents and discuss the on-site operational energy production performance. This study may serve as a reference for developing large-scale floating PV farms in coastal marine conditions.

Assessment of floating solar photovoltaic potential in India’s existing hydropower reservoirs

The hydropower share of the Indian electrical sector has declined significantly over time, and a greater reliance on the complementation of thermoelectric power plants to meet energy demand. This issue has led to an increase in greenhouse gas emissions, which has exacerbated climate change and altered rainfall regimes in numerous sections of the country, as well as increased potential evapotranspiration. Installing floating solar photovoltaic (FSPV) plants in existing hydropower reservoirs would increase the hydropower share and reduce evaporation losses. FSPV is also assisting the country in meeting the net-zero carbon emission target and India's rapidly rising population's current and future energy needs. Using very accurate water surface data from the country's 117 hydroelectric reservoirs, this study presents a comprehensive analysis of the potential of FSPV installations in Indian hydropower reservoirs. In addition to electricity generation, CO2 savings and evaporation savings are calculated. The additional hydropower generated, as well as the number of people who could be able to benefit due to these water savings, are also estimated at reservoir level for four different scenarios considering pontoon type of floating structure. The results show that with total coverage of less than 4% area of hydroelectric reservoirs, existing hydropower plants can double their installed power capacity and increase their electricity output by 52%, producing an additional 66.56 TWh per year. In this case, water savings could total 837 million m3/year, resulting in a 1.566 TWh of additional annual hydroelectricity generation.

Review of Installation Status and Major Environmental Issues of Floating Photovoltaic Power Plants (FPVs)

Objectives : After investigation of types, characteristics, and domestic and overseas installation cases of floating photovoltaic power plants (FPVs), both power generation capacity and coverage ratio of the FPVs were analyzed, and the major environmental issues impacting on water quality and aquatic ecosystem were reviewed.Methods : Both information and data of the FPVs extracted from existing literature and provided by the FPVs installation companies were statistically analyzed.Results and Discussion : FPVs divided into three types such as pontoon type, frame type, and solar tracking type are installed in various ways by country and region. As of the second half of 2018, the global power generation capacity of FPVs is 1.3 GWp, and FPVs have been intensively installed in China, Japan, Korea, Taiwan, and UK. While the pontoon type has been mainly installed in other countries except Korea, the frame type was mainly installed in Korea. Among various water resources, FPVs installed in agricultural water resources have various power generation capacity and coverage ratio whereas FPVs installed in industrial, rainwater storage, and other water resources have relatively high power generation capacity and coverage ratio. Compared to FPVs installed in other water resources, FPVs installed in drinking water resources have relatively low power generation capacity and coverage ratio. After reviewing the major environmental issues related to FPVs (i.e., leaching of hazardous substances, deterioration of water quality and aquatic ecosystem, changes in water temperature and illumination, and disturbance of aquatic ecosystem), the impacts of the FPVs on water environment are found to be insignificant, and the positive effects (i.e., mitigation of green tide and restoration of the aquatic ecosystem) are confirmed.Conclusions : Although the impacts of the FPVs on water environment (water quality and aquatic ecosystem) are found to be insignificant, additional experiments reflecting extreme conditions and long-term continuous monitoring of water quality and aquatic ecosystem in terms of coverage ratio, array and type of FPVs are required.

Scattering of gravity waves by a pontoon type breakwater with a series of pervious and impervious skirt walls

ABSTRACT The scattering of surface gravity waves by a skirt wall breakwater is analysed in two dimensions under the assumption of small-amplitude wave theory. The oscillatory wave past the porous skirt walls is assumed to follow Darcy’s law. The boundary value problem is solved using multi-domain boundary element method to obtain the numerical results for the different number of porous skirt walls, relative pontoon width, relative submergence and different porosity of the skirt walls. The study reveals that an increase in the number of skirt walls from one to four can reduce the wave transmission by 61% but at the expense of an increase in horizontal wave force by 90% and decrease in the vertical force by 31%. A minimum of two-skirt walls is needed for reducing wave transmission. Skirt wall porosity of 0.40 is recommended for field applications considering the trade-off between the wave transmission and wave forces.

Hydroelastic analysis of a truss pontoon Mobile Offshore Base

Very Large Floating Structures (VLFS) are one among the solution to pursue an environmentally friendly and sustainable technology in birthing land from the sea. VLFS are extra-large in size and mostly extra-long in span. VLFS may be classified into two broad categories, namely the pontoon type and semi-submersible type. The pontoon-type VLFS is a flat box structure floating on the sea surface and suitable in regions with lower sea state. The semi-submersible VLFS has a deck raised above the sea level and supported by columns which are connected to submerged pontoons and are subjected to less wave forces. These structures are very flexible compared to other kinds of offshore structures, and its elastic deformations are more important than their rigid body motions. This paper presents hydroelastic analysis carried out on an innovative VLFS called truss pontoon Mobile Offshore Base (MOB) platform concept proposed by Srinivasan and Sundaravadivelu (2013). The truss pontoon MOB is modelled and hydroelastic analysis is carried out using HYDRAN-XR for regular 0 waves heading angle. Results are presented for variation of added mass and damping coefficients, diffraction and wave excitation forces, RAOs for translational, rotation and deformational modes and vertical displacement at salient sections with respect to wave periods.

Observation Class ROV のテザーケーブル運動の推定

A technique for motion estimation of a tether cable of an observation class ROV is proposed in this paper. A simulation procedure based on the lumped mass method is adopted for the motion and shape estimation of the cable. Deployment of the tether cable from a starting point is approximately treated locating the mass points at the starting point. These mass points are deployed and follow the leading part of the cable. The simulation results are compared with results from tank experiments and the validity of the simulation technique is confirmed. Examples of path planning for the inspection of a pontoon type floating structure is also shown.

Efficient computation of cross-spectral densities in the stochastic modelling of waves and wave loads

A new method is presented for efficient calculation of auto- and cross-spectral densities in the stochastic modelling of ocean waves and wave loads. As part of the short-term response analyses, the method may contribute to more efficient long-term response prediction. Specifically the cross-spectral densities of the first order wave excitation forces are considered, but the method is straightforwardly generalized to other cross-spectral densities, e.g. for wave elevation, wave kinematics or second order loads. The method can be used with any choice of directional spreading function, but special attention is given to the commonly used cos-2s type directional distribution. In addition to the development of the new method, the traditional method using the trapezoidal rule for numerical quadrature is improved by developing an adaptive way of choosing the number of integration points. The accuracy of the adaptive method and the new method is investigated, revealing rapid convergence for both methods. However, the new method appears more robust as it avoids so-called spurious hat errors. When applied to two different pontoon type floating bridges the adaptive method and the new method both achieve a great improvement in computational effort compared to the traditional trapezoidal rule method. When the dimensions of the floating bridge increase, i.e. the number of pontoons and their relative distances increase, the new method is superior with respect to computation time.

IMPACT OF FISH AGGREGATING DEVICE ON SUSTAINABLE CAPTURE FISHERIES

The use of rumpon, a type of Fish Aggregating Device (FAD), has been traditional in Indonesia, particularly in eastern Indonesia waters since time immemorial (Reuter 1938; Nasution et al. 1986; Monintja 1976). The traditional tuna fishermen in Mamuju waters in the Province of South Celebes have used rumpons for a long time, although there is no record when the device was first used (Nasution et al. 1986). Any structure designed or made to attract free schooling fishes: rumpon (Indonesia), tendak (West Java), uncang (Sumatera), rompong (Sulawesi), payaos (Philippines). Local fishermen claimed that they learned how to construct the rumpon from their ancestors, but did not apply the device extensively until 1985 because of the low profitability of catching the swift swimming fishes. The use of rumpon for fishing activities has improved the effectiveness and efficiency of several fishing gear. However, the fast growing of rumpon utilization has raised a great concern on the sustainability of the fish resources. The rumpon management for responsible fisheries should consider the aspects of biology, location, environment, fishing gear, social and economic. The existing condition of rumpon has not fully understood and its usage in a responsible manner further elaboration also needed. For that purpose, the information of the past and present situation of rumpon in Indonesia will be important for further management. The main data were collected and compiled from various references, annual report of the Directorate General of Fisheries and research report of Central Research Institute for Fisheries. Additional data were made available from local fisheries agencies or related institutions. Structure of the rumpon installed in the Provinces of North Sumatera, West Sumatra, Lampung, West Java, East Java, North Celebes, Central Celebes, South Celebes, maluku and Papua are given in detail. There are 2 types of rumpon : the deep sea rumpon and shallow water rumpon. The differences among the rumpons in those areas are mostly found in material of mooring line, shape and material of float and structure of the attracting components. The mooring line is mostly made of polyethylene of 12-25 mm in diameter or nylon of 5-10 mm in diameter. There are wide variations of shape of floats. Generally they are divide into pontoon type or box shape made of steel and raft type made of bamboos. Attractors are made of coconut leaves, nipah leaves and pinag leaves. Some attractors are attached to the mooring line and the others are hung down from the float. They are operated in wide range of water depth from 20 to 1500 m. The fishing ground conditions, bottom topography and bottom configuration are among the factors considered for the rumpon design and construction. The differences in construction are mainly due to the rumpon location, target species in each area and the fishing gear applied. Keywords : fish aggregating device, rumpon, sustainable fisheries, Indonesia

Response analysis and optimum configuration of a modular floating structure with flexible connectors

In the present paper, a numerical analysis framework evaluating the connectors’ internal loads of a modular Pontoon type Floating Structure (PFS) as well as for identifying the PFS's optimum configuration under the action of regular waves is developed and presented. The PFS consists of flexible floating modules (pontoons) connected with flexible connectors in longitudinal and/or transverse directions. The numerical analysis framework includes: (a) a frequency domain ‘wet’ hydroelastic analysis for computing the PFS's ‘wet’ hydroelastic response and the connectors’ internal loads and (b) a genetic algorithms based optimization process for identifying the optimum configuration of the PFS considering predefined performance criteria. Different configurations of the PFS under the action of normal and oblique waves are taken into account, considering different number and layout of modules (grid type) and different values of the connectors’ rotational stiffness. The effect of the connector's rotational stiffness and the grid type of the PFS on the hydroelastic response and on the connectors’ internal loads is analyzed. For specific wave field characteristics, the optimum design configuration of the PFS is identified through the aforementioned optimization process in terms of performance criteria related to: (a) the vertical hydroelastic response at any predefined point of the deck of the PFS and (b) the internal loads of the PFS's connectors. The results obtained demonstrate the complex relationship between the internal loads of the connectors and the hydroelastic response of the examined PFS configurations with the connectors’ rotational stiffness and the PFS's grid type as well as with the excitation. They also demonstrate the applicability of the developed numerical analysis framework in order to properly direct the PFS's design towards a most preferable optimum configuration.

Analytical study on hydrodynamic motions and structural behaviors of hybrid floating structure

In this study, a hybrid floating structure with cylinder was introduced to reduce the hydrodynamic motions of the pontoon type. The hybrid floating structure is composed of cylinders and semi-opened side sections to penetrate the wave impact energy. In order to exactly investigate the hydrodynamic motions and structural behavior of the hybrid floating structure under the wave loadings, integrated analysis of hydrodynamic and structural behavior were carried out on the hybrid floating structure. Firstly, the hydrodynamic analyses were performed on the hybrid and pontoon models. Then, the wave-induced hydrodynamic pressures resulting from hydrodynamic analysis were directly mapped to the structural analysis model. And, finally, the structural analyses were carried out on the hybrid and pontoon models. As a result of this study, it was learned that the hybrid model of this study was showed to have more favorable hydrodynamic motions than the pontoon model. The surge motion was indicated even smaller motion at all over wave periods from 4.0 to 10.0 sec, and the heave and pitch motions indicated smaller motions beyond its wave period of 6.5 sec. However, the hybrid model was shown more unfavorable structural behavior than the pontoon model. High concentrated stress occurred at the bottom slab of the bow and stern part where the cylinder wall was connected to the bottom slab. Also, the hybrid model behaved with the elastic body motion due to weak stiffness of floating body and caused a large stress variation at the pure slab section between the cylinder walls. Hence, in order to overcome these problems, some alternatives which could be easily obtained from the simple modification of structural details were proposed.

Novel offshore application of photovoltaics in comparison to conventional marine renewable energy technologies

An original proposal for the deployment of photovoltaic (PV) systems in offshore environments is presented in this paper. Crystalline PV panels are considered where they are deployed on pontoon type structures and there are six case study examples precedent practise of such deployments in lakes and reservoirs (but not seas). The authors put forward an alternative based on flexible thin film PV that floats directly on the waterline. The paper then concentrates on the techno-economic appraisal of offshore PV systems in comparison to conventional marine renewable energy technologies. The difficulties of comparing offshore technology projects developed in various countries, using different currencies and in different years are overcome so that such comparisons are made on an equitable basis. The discounted cost of electricity generated by each scheme is determined, including capital expenditure (CAPEX) and yearly operation and maintenance (O&M) costs.Actual wind, tidal (current turbines and barrages) and wave projects were considered in the analysis alongside crystalline and thin film PV. Thin film PV was found to be economically competitive with offshore wind energy projects for latitudes ranging from 45°N to 45°S. The specific yield, assessed in terms of GWh/km2 was higher for thin film PV than for wind, wave and tidal barrage systems. In addition the specific installed capacity, expressed in MW/km2 was also higher than the other conventional technologies considered (excluding tidal current turbines).

Wave Induced Hydraulic Pressure by Wave Conditions of Pontoon Typed Floating Structures

In this study, in order to verify wave induced buoyancy effects by wave conditions of wave height and period, experimental studies were conducted to the floating structures of pontoon type. A series of small-scale tests with various wave cases were performed to the pontoon models. Two small-scale pontoon models having different bottom details were fabricated and tested under the five different wave cases. Six hydraulic pressure gauges were attached on the bottom of pontoon models and wave induced hydraulic pressure was measured during the tests. Finally, hydraulic pressure subjected to the bottom of pontoon models were compared with each other. As the results of this study, it was found that wave induced hydraulic pressures at bottom were dependent on the wave period as well as wave height, and waffled bottom shape hardly influenced on wave induced hydraulic pressure.

MPS法を用いた津波中の浮体による衝突力に関する研究

The present paper describes the application of the moving particle semi-implicit method to a prediction of collision forces on water-front facilities induced by floating vessels washed onto the apron by tsunami. Effectiveness of the application is verified. Solitary waves are applied to simulated tsunamis in numerical simulation and to the model experiments. A pontoon type floating body is applied to floating structures in numerical simulations using the MPS method. The present calculation results are compared with the experimental results and the applicability of MPS method is discussed. Further, after being washed onto the wharf by tsunami, the characteristics of collision force on water-front facilities induced by the floating bodies are discussed.

Research on floating wind turbines: a literature survey

This article presents a literature survey of research and development on floating wind turbines. The various, proposed conceptual designs for floating platforms used for floating wind turbines are described and the working principles of these various floater concepts are outlined. This is followed by an overview of the research work that has been undertaken pertaining to floating wind turbine technology by several research institutes and the academic community. The research work undertaken to date is reviewed categorically according to the proposed floater concept (spar-buoy type, TLP type, semi-submersible type, pontoon type and others) as per sections 3–7. Based on the research work undertaken thus far, recommendations for future work are suggested.

A comparative study of the biomass-based and individual-based models of blue mussels

The performance of a biomass-based model is compared with that of an individual-based model for a blue mussel Mytilus galloprovincialis. The mathematical models are developed to predict the environmental impacts of blue mussels, which adhere to the surface of coastal artificial structures and vary the surrounding material cycle with their feeding and respiratory activities. The existing biomass-based model is based on Scope for Growth (SFG) concept and allometric relations between body size and physiological rates. One problem of this approach is that it does not discriminate between fed and starved mussels in the mussel bed. However, mussels are usually attached to each other in several layers, with subsequent competition for food among them. Hence, some of the mussels are shoved to the inner layer of the mussel bed and must be starved due to their unfavorable position. They continue living by consuming the reserved materials little by little by means of standard respiration, therefore they does not contribute much to food ingestion and oxygen consumption rates of the mussel bed. In the present study, an individual-based model is developed to describe the dynamics of mussels as controlled by Competition for Space and Food (CSF) availability. The model consists of a physiological growth submodel based on Dynamic Energy Budget (DEB) concept and a competition submodel. Both the biomass-based and individual-based models are applied to the mussels growing on the artificial substrata suspended from the top of a pontoon type floating platform anchored in the head of Tokyo Bay in Japan. Then the observed results of growth and oxygen consumption rate of mussels are compared with the predicted results by means of both models. Consequently, the performance of the biomass-based model is sufficient when the mussel bed forms mono layer, however the performance of the individual-based model is better in the case when the mussel bed has several layers.

ポンツーン型浮体の波浪中弾性応答解析へのＨａｍｉｌｔｏｎ−Ｄｉｒｉｃｈｌｅｔ原理の適用（第２報：任意平面形状浮体への適用）

Many analytical methods have been proposed to calculate hydroelastic responses of a very large pontoon type structure in waves.In relation to the elastic response of such pontoon type structure in waves, Isshiki and Nagata proposed the Modified Hamilton-Dirichlet's Principle 2, which is expressed only using the velocity potential. It is the variational principles related to motions of the elastic floating plate on a water surface.In this study, in order to calculate the wave-induced responses of an elastic floating plate in waves, a new method was proposed which uses the Modified Hamilton-Dirichlet's Principle 2and the eigenfunction expansion method for fluid motion. The velocity potentials in fluid regions with and without the plate are expanded by eigenfunctions in vertical mode which satisfy the governing equations and free-surface conditions, taking into account the presence of the plate in the same manner as Kim and Ertekin. In this method, Modified Hamilton-Dirichlet's Principle 2 is finally reduced to a variational equation which corresponds to boundary conditions on the plate's edge. The formulation of proposed method is applicable for the floating plate of arbitrary plan geometry.Calculated results of two kinds of rectangular and L-shaped floating plate in an open sea are compared with experimental results.Good agreement is found between computed and experimental results.

폰툰형 부체구조물과 몰수평판에 작용하는 라디에이션 유체력에 관한 연구 : 몰수평판에 의한 유체력 간섭 영향

초대형 부체구조물은 파랑중 유탄성 변형이 심하게 발생하기 때문에 수평식 몰수평판과 같은 파랑에너지 흡수장치의 부가적인 개발이 요구된다. 본 연구에서는 몰수평판에 의해 야기되는 유체력 간섭현상이 폰툰형 부체구조물에 작용하는 라디에이션 유체력에 어떠한 영향을 미치는지 수치적인 해석을 통하여 그 특성을 파악하고자 한다. 폰툰형 부체구조물과 몰수평판의 상하운동에 의해 발생하는 라디에이션 유체력을 계산하기 위해 고정격자계와 이동격자계로 구성되는 중합격자법을 토대로 한 수치계산법을 개발한다. 또한 쇄파현상과 같은 비선형성이 강한 자유표면 문제를 해결하기 위하여 유한차분법을 적용하여 시뮬레이션을 실시하고 그 결과를 실험데이터와 비교함으로서 수치계산법의 신뢰성을 확인한다. 몰수평판에 의해 발생하는 유체력 간섭 영향의 특성을 분석하여 부체구조물의 파랑중 유탄성 변형에 미치는 그 효과에 대하여 논의한다. Hydroelastic deformation of pontoon type floating structure in waves is critical in structural design. Therefore, it is necessary to develop additional technology that make to dissipate the wave energy as the submerged horizontal plate. In this study, we investigate the characteristics of hydrodynamic interaction effect by the submerged plate affecting to the radiation forces on a pontoon type floating structure using numerical analysis. We have developed the numerical method based on the composite grid system that consists of moving and fixed grid to compute the radiation forces due to the heaving motion of pontoon type floating structure and submerged plate. The numerical simulations based on the finite difference method are carried out to solve the fully nonlinear free surface involving the breaking waves and compared with the experimental data to confirm the reliability of the numerical method. Then, we discuss the interaction effects on the hydrodynamic forces that could influence on the hydroelastic response of floating structure.

Numerical modeling of dynamic responses and mooring forces of submerged floating breakwater

Using the volume of fluid (VOF) method, a numerical model is developed to estimate the nonlinear dynamics of a pontoon type moored submerged breakwater under wave action and the forces acting on the mooring lines, for both the vertical and inclined mooring alignments. The model is developed for a two-dimensional wave field in a vertical plane. The finite displacements of the breakwater such as sway, heave and roll in a very small time step are considered and the numerical grid cells intersected by the breakwater surfaces for changing its position due to wave action are treated using the concept of porous body model. Also, two-dimensional experimental studies are carried out to investigate the performance of the proposed model. The comparison of the computed and measured results reveals that the developed numerical model can reproduce well the dynamics of the floating body and the mooring line forces.

Case Study on Habitability of Superstructure built on Floating Structure

Researches on a superstructure built on a floating structure in the shape of pontoon type have begun in recent years. A superstructure responds by wave load and it is important to evaluate its habitability. The purpose of this study is evaluation and investigation of habitability of a superstructure due to wave for 10 year return period. In this study, response analyses of the superstructure built on middle-sized floating structure due to the waves of three cases were carried out by 3-D integration analysis, which means analyzing the calculation model integrated a superstructure with a floating structure, and its habitability was evaluated by the evaluation diagrams. As the result, the habitability differed by each wave condition The use of a superstructure is restricted according to the disposition of a floating structure for incident wave angle.