9. Subtask9: Study of innovative and leading technology

9.1 R&D Goals

WE-NET is a long-term project. Therefore, in promoting the project, there may be some certain innovative and leading technologies not included in present objects of R&D, although they are promising for the future. On the other hand, incorporation of existing technologies into WE-NET project may be necessary depending upon their technological improvements.

Such innovative and leading technologies and existing technologies are to be studied, investigated, and evaluated, and depending on the situation further studies are to be conducted so that useful suggestions and proposals may be made as to the course for the WE-NET project to follow, as well as its R&D.

9.2 Results in FY 1998

9.2.1 Research and evaluation of innovative and leading technologies

6 proposals were collected in FY 1998. And 7 proposed technologies, including 1 proposal collected in the latter half of FY 1997, were evaluated to prioritize for feasibility study. These are summarized in Table 9-2-1.

9.2.2 Study of innovative and leading technologies

(1) Evaluation of feasibility studies conducted in FY 1997

3 feasibility studies conducted in FY 1997 were evaluated. They were evaluated as follows:

  1. Feasibility study of hydrogen production by effective utilization of wavelength dependent on solar energy

    This study investigated hydrogen production systems utilizing high-temperature steam electrolysis cells combined with selective transmission/reflection film and solar cells. In these systems, the film transmits wavelengths in the sunlight used by solar cells for conversion to electricity, and reflects those not used by the solar cells for heat collection, then these electricity and heat are supplied to high-temperature steam electrolysis cells to produce hydrogen. Though the systems investigated this time turned out to be wasting heat not using up all, efficiency will be improved further by taking in the technologies to increase heat utilization. To judge how good the system utilizing selective transmission/reflection film is, it should be compared with various other hydrogen production systems utilizing solar energy and be evaluated. Therefore, "Feasibility study of hydrogen production by effective utilization of solar energy" will be conducted in FY 1998.

  2. Evaluation of economic feasibility of magnetic refrigeration technology for large-scale liquefaction of hydrogen

    The efficiency and capital cost of a 300 ton/day magnetic liquefier were calculated to be 60% and US$100 million, respectively. Magnetic refrigeration is an interesting technology for a hydrogen liquefier that has possibility to have great advantage over gas-cycle refrigeration in both efficiency and capital cost, and the idea of cooling from 300K to 20K only by magnetic refrigeration is innovative. However, it is not clear whether high-speed heat exchange between large amount of helium gas and magnetic materials rotating at high speed is technically feasible or not. Therefore, this point will be the subject to be examined from now on.

  3. Feasibility study of hydrogen production from biomass

    The comprehensive investigation of the status of biomass resources and technology gave the valuable information. From the viewpoint of cost, it was suggested that there were more advantageous biomass conversion such as to bio-oil than that to hydrogen for the time being, but biomass conversion to hydrogen pays enough from the viewpoint of energy because its energy payback time is short enough. We are going to utilize the obtained information for the examination of hydrogen introduction strategies, scenarios, and so on.

(2) Feasibility studies conducted in FY 1998

Based on the additional examination theme derived from above-mentioned evaluation results of feasibility studies conducted in FY 1997 and on the evaluation results of proposals summarized in Table 9-2-1, theme of feasibility studies in FY 1998 were selected and 5 feasibility studies were conducted. They were evaluated as follows:

  1. Feasibility study of hydrogen production by effective utilization of solar energy.

    At first the system using selective transmission/reflection film, which separates sunlight into for solar photovoltaic use and solar thermal use according to its wavelength, were expected to be promising. However, contrary to our expectations, the system combined with solar reflector and stirling engine turned out to be more excellent from the viewpoint of both efficiency and energy payback time. This study resulted in confirming the extremely ordinary matter because the efficiency of stirling engine is 48% and higher than that of solar cell; however, this study could clarify what kind of system utilizes solar energy most effectively to produce hydrogen. We have decided to put an end to this study and not to put it into the fundamental research stage.

  2. Feasibility study of methanol-fueled power generation systems

    It was shown that carbon dioxide recovery power generation system fueled by methanol can be constructed, which efficiency is a little higher than existing LNG-fueled thermal power generation. And this power generation cycle fueled by methanol turned out to be about the same economics as the one fueled by LNG. This technology seems to be worth investigating as a power generation technology in the intermediate term of transition to WE-NET system. We have decided to entrust further examination to the "Carbon dioxide recovery closed cycle high-efficiency gas turbine" project, which is being planned as an independent project from WE-NET, and to watch how it would go.

  3. Conceptual design of high-efficiency production system for high-efficiency solar cell by the 10GW/year scale production process

    A large-scale production process, which uses vapor deposition considering the recycling of material gas and substrates, was proposed for manufacturing of thin-film crystal silicon photovoltaic (PV) cell. And it was clarified that this method could drastically reduce the percentage of silicon wafer cost in the PV module. Although we need to reduce the cost of not only wafer manufacturing process but also module assembly processes, support, and so on, for the economic improvement in PV generation system, the cost reduction of Si wafer will become an incentive to that. Because this technology can make it more feasible economically to produce hydrogen by utilizing PV cells and electrolysis, we are going to utilize the obtained information for the examination of hydrogen introduction strategies, scenarios, and so on.

  4. Investigation of catalysis materials for hydrogen combustion and catalytic combustion systems

    In the catalytic combustion of hydrogen, the possibility of precise control of combustion speed by optimizing catalysis materials and reaction conditions over a wide range of temperature, from room temperature to 1000°C, was showed. And as one of the strong application utilizing these good points, an idea of high-efficiency gas turbine, even with a relatively low combustion temperature, using isothermal expansion combustion was proposed. This isothermal expansion combustion gas turbine has large possibility as a hydrogen utilization technology. It is necessary to clarify the system image of the gas turbine and to investigate the feasibility of isothermal expansion combustion further.

  5. Evaluation of technological and economic feasibility of production of high-temperature steam electrolysis cell / solid oxide fuel cell by the synthesis from aqueous solutions

    There is no doubt that this method has possibility as a production technology for high-temperature steam electrolysis cells or solid oxide fuel cells. However, though particles of ceramic materials, such as electrolyte, electrode, interconnection, and so on, have been synthesized from aqueous solutions, this technology is still in the stage that films have not been made. Furthermore, in the actual high-temperature use of the films synthesized from aqueous solutions at ordinary temperature, there must be some problems to be solved, such as shrinkage, deformation, crack, and so on. Therefore, we are going not to adopt this technology in the WE-NET project but to collect information about the progress in research and development for the time being.

9.2.3 Examination of new areas and items of technology development

Promising technologies to be reflected on the WE-NET project were examined based on the trends in the new technologies acquired from the research and investigation so far. And then the following 2 candidates were selected for the fundamental research subjects to be started in Phase II (final decision is to be made at the first fiscal year of Phase II ):
  1. Hydrogen liquefaction by magnetic refrigeration technology
  2. Catalytic combustion gas turbine

9.3 Subject in future

In Phase I, the trend of related technologies were continuously watched, and from among them the innovative and leading technologies those incorporation into WE-NET project may be necessary were extracted, investigated and evaluated. In consequence, we could find promising seeds such as hydrogen liquefaction by magnetic refrigeration and could provide the project with useful information to forecast the hydrogen technology in the future, so we could almost achieve the goal of Phase I of this study.

For keeping effectiveness of the WE-NET project also from now on, the trend of related technologies should be watched continuously.

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