3C.Research on Effective Use of Ocean Space and Renewable Energy

Background and Objectives

  • Highly effective use of ocean space, along with the energy of sea waves, ocean wind, and other renewable sources, is crucial for Japan as a maritime nation; such technologies are indispensable for revitalizing the country's economy. Alternative energies have gained greater social importance following the nuclear plant disaster caused by the Great East Japan Earthquake.
  • However, the weather conditions in the coastal areas of Japan are among the most extreme in the world, and thus the advanced utilization of ocean space requires novel technologies to overcome the adverse climate.
  • This research theme deals with the organization of technical information and the development of technologies to support the efficient use of ocean energy and the development of remote island infrastructure for revitalizing the economy of Japan as a maritime nation. Our wide-ranging efforts are focusing on the implementation of wave power generation systems, development of offshore wind power generation in port areas, technological development for the effective use of marine mineral resources, and so on.

Research topics

 The research on the effective use of ocean space and renewable energy comprises the following three subthemes:

  1. Effective Utilization of the Ocean Space
     We are developing the elemental technologies required for the effective use of ocean space. In particular, the utilization of sea areas around remote islands has attracted much public attention in terms of protecting the nation's maritime rights and interests. This subtheme focuses on developing elemental technologies for correctly understanding as well as simulating the distribution of sea waves around reefs and in other areas with complex bathymetries.
  2. Effective Utilization of the Ocean Renewable Energy
     We are focusing on research in wave power and wind power,which are the most promising among various ocean energy sources, and which have been successfully studied by PARI. The research activities start with a review of technical problems related to the development of medium-sized wind power generation,wave power generation, and other technologies to support the energy self-sufficiency of remote islands, then we try to create technical proposals for the practical utilization of wave and wind energy at ports within the time-span of our current mid-term plan.
  3. Development of the new technologies for Ocean Investigation and Construction
     We are developing the new technologies needed to properly and efficiently utilize the research results of the above two subthemes in coastal areas. Specifically, by utilizing technologies that we have accumulated through studies and technology developments,such as remotely operated systems using Augmented Reality (AR) and Virtual Reality (VR), control systems using Remotely Operated underwater Vehicles (ROV) and Autonomous Underwater Vehicles (AUV), and submerged acoustic devices including underwater acoustic cameras, we are conducting surveys and operations related to marine observation equipment and other marine facilities, as well as R&D on survey systems and operation systems to contribute to seabed resource exploration and marine environment investigation. Moreover, we are confirming the feasibility of such systems via verification experiments. We aim to bring into practice specific technologies to improve the reliability of marine surveys and construction in this mid-term plan.

Activities in FY 2014

  • Regarding the technological development for utilizing mooring
    facilities to be constructed in offshore isolated reef areas,
    we conducted plane model experiments for wave/flow fields
    around isolated reefs and constructed a calculation system for
    planar wave places using a Boussinesq model introducing the
    nesting technique that enables efficient calculations, considering
    the results of the above experiments as the verification data.
    We also started to study how to embed the swing analysis of
    moored ships and floating bodies in this calculation system.

Figure 1.1.1.15 Comparison between the result of an experiment on the wave transformation around an isolated reef and the result of a theoretical calculation

  • Regarding the study on the development of ocean resources in remote
    islands, we studied an entire system of mining, transportation, waste
    disposal, and others, and then designed the concept of the port structure
    in remote islands. Furthermore, we studied the basic design and
    launching/lifting methods of mining equipment in deep water, conducted
    a behavior analysis and water tank tests of deep water mineral lifting
    pipes, and studied methods for the soil test of mud on the seabed as well
    as methods for the design and construction of waste disposal areas.

Figure 1.1.1.16 Proposal of a logistics system for marine mineral resource development

  • Regarding the investigation and analysis on the application of
    ocean energy conversion systems to port areas, we carried
    out on-site verification tests (at Sakata Port) as to the stability
    against tsunamis and power generation efficiency of multiple
    resonance type wave activated power generation systems. We
    also conducted technical verification of the ocean wind state observation
    system using the weather and oceanographic observation
    data obtained by the ocean wind state observation tower
    and weather meter installed in the sea area off Kitakyushu City
  • Regarding the basic study on the development of marine and
    submarine unmanned observation systems, we confirmed the
    response characteristics of the tensiometer used for detecting
    the entanglement of chains of the mooring equipment of GPS
    wave meters by conducting water tank tests, and proposed
    methods for investigating the durability of the mooring equipment.
    We also created and tested new buoys for tracking floating
    heavy oil, and considered installing oil detection sensors.
  • Regarding the research and development of methodology for downsizing
    the 3-D wide-angle moving image sonar system, we debugged
    the control and analysis program of the equipment, put the underwater
    part into a watertight container as a water tank testing machine,
    and carried out performance verification tests in the water tank.

 

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