Summary

International Clean Energy Network Using Hydrogen Conversion (WE-NET) aims at contribution to solving global environmental problems by means of large-scale and effective utilization of clean and renewable energies such as hydraulic, solar, and wind which are available widely on the earth. Its purpose is also to establish technologies capable of introducing an international energy network utilized in wide fields such as hydrogen production from these energies, conversion of hydrogen as necessary, transportation, storage, generation of power, fuel for transportation, and town gas, in order to satisfy energy demands, and to develop core elementary technology as well as preparation conceptual design of the total system.

Phase I of WE-NET scheduled for six years from FY 1993 aims at establishment of basic technologies for hydrogen production, hydrogen transportation and storage, and utilization of hydrogen, by means of necessary investigation, basic researches, and studies for elementary technologies, in order to obtain information necessary for the optimum design of the total system and establish technologies necessary for the design and construction of a pilot plant. In addition, studies for technologies adaptable to the project in future are intended to be carried out in parallel with the above to be properly reflected on every research and development items.

The results obtained in R&D of Phase I will be reflected on realization of the plans of Phase II. Fig 1 shows the schematic illustration of WE-NET.

1. Items and targets of R&D

R&D for Phase I is divided into the following nine subtasks.

1.1 Subtask 1: Investigation and study for evaluating and reviewing R&D

Regarding each individual technology development constituting systems such as hydrogen utilization technologies including hydrogen production, hydrogen transportation and storage, and hydrogen-combustion turbines of WE-NET, studies are to be implemented for the constant overall coordination of the project, the overall evaluation of developed results, and the optimization of development schedule.
In addition, tendencies of internal and external technology development are to be studied to reflect them upon the future work of the project programs.

1.2 Subtask 2: Review and investigation for promoting international cooperation

In order to establish a worldwide system, periodic information exchanges are performed with international organizations and relating countries, while the progressing procedures and measures are to be studied for developing the project as a international joint research.

1.3 Subtask 3: Conceptual design of the total system

Development of a conceptual design of the total system consisting of such facilities as power generation using renewable energy, hydrogen production, transportation medium production, storage, transportation, and utilization is to be conducted to make the technological and economical evaluation. The effect of the introduction of hydrogen energy is to be estimated in a world-wide level and individual country level. Development of safety measures and evaluation technologies is to be conducted from the perspective of the total WE-NET system.

1.4 Subtask 4: Development of hydrogen production technologies

In hydrogen production methods by water electrolysis, there are the alkali water electrolysis which has been commercialized, solid polymer electrolyte water electrolysis which is promising in future, and high temperature vapor electrolysis which is a step verifying its principle. Among these methods, in Phase I, the investigation necessary for achievement large scaling-up and long life is to be carried out for the solid polymer electrolyte water electrolysis which is expected in high efficiency and high current density. Therefore, technologies necessary for a pilot plant are to be established by development of elementary factors such as solid polymer electrolyte (ion exchange membrane), anode and cathode catalysts, and materials for electrolytic baths, and implementation of bench scale tests.

1.5 Subtask 5: Development of hydrogen transportation and storage technologies

Liquid hydrogen, hydrogen gas, ammonia, methanol, and cyclohexane have been considered as media for hydrogen transportation. Among them, transportation of liquid hydrogen has not yet been started to be developed both internally and externally. However, liquid hydrogen is to be adopted as an object of this R&D for an approach promising in the near future, from the perspective of easy mass transportation, simple conversion, and convenience in using at consuming areas, as the result of a careful study because this is an important developing theme.

However, the other hydrogen transporting media are to be studied in the conceptual design of the total system in Subtask 3, taking the states of R&D and realization into consideration.

Accordingly, necessary investigations, basic researches, and elementary technology development are to be conducted for the following items regarding the hydrogen production, transportation, and storage, in order to obtain findings necessary to determine an optimum system for long-distance marine transportation and small-scale storage and small-scale transportation.

(1) Development of large-capacity hydrogen liquefaction facilities
(2) Development of liquid hydrogen transportation tanker
(3) Development of liquid hydrogen storage facilities

  1. Development of large-capacity liquid hydrogen storage facilities
  2. Development of small-scale liquid hydrogen storage facilities
(4) Development of devices for common use
  1. Development of large-capacity liquid hydrogen pump
  2. Development of adiabatic piping
  3. Development of liquid hydrogen valve
  4. Development of instrumentation
(5) Development of hydrogen absorbing alloys for small-scale transporting and storage system

1.6 Subtask 6: Development of cryogenic materials technologies

Although the existing materials useable in the cryogenic range (-253ｰC) are available in certain cases at present, there is few data regarding toughness, fatigue, and serration of structural materials at the temperature range of liquid hydrogen. In addition, since structural materials used in the liquid hydrogen environment may contact gas hydrogen at room temperature, they must have the strong property against hydrogen embrittlement. On the other hand, materials useable in the liquid hydrogen range are hard to be welded, and problems of cracks in welded parts are caused if welding is made. Therefore, structural materials useable in the liquid hydrogen condition and their proper welding methods are to be studied, by development of new materials as necessary as well as obtaining of basic data for the existing materials. The requirements from materials are to be determined relating to the development of hydrogen transportation and storage describing in Subtask 5.

1.7 Subtask 7: Feasibility study on utilization of hydrogen energy

Investigation, studies, and presentation of applicable technologies are to be conducted concerning the utilizing technologies and demand of hydrogen in future in various fields, such as electric power, industry, transportation, and civil use, in various methods of using hydrogen gas, liquid hydrogen, and methanol, so that the merits and demerits of each technologies are to be clarified and the themes to be developed in hydrogen utilizing technologies are to be selected. In addition, investigation concerning technology utilizing cryogenic energyハof liquid hydrogen is to be studied to evaluate the application technologies.

Development of elementary technology for each hydrogen utilizing technologies is to be conducted as necessary.

1.8 Subtask 8: Development of hydrogen-combustion turbine

The required investigation and development of elementary technologies for the following items are to be studied for hydrogen combustion turbines which are expected because of their extraordinary high efficiency as a hydrogen utilizing technology, and technologies necessary for development of a pilot plant is to be established.

(1) Study for an optimum system for hydrogen-combustion turbine
(2) Development of the combustion control technologies
(3) Development of turbine-blades, rotor and other major components
(4) Development of major auxiliary equipment
(5) Development of super-pyrogenic materials

1.9 Subtask 9: Study of innovative and leading technologies

WE-NET is a superlong-term project aiming at full-scale realization in the year around 2030. Therefore, 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 as necessary the minimum elementary researches are to be conducted to reflect obtained promising technologies on WE-NET project. The development schedule of R&D items mentioned above is shown in Table 1.

2. Summary of FY 1995 Results

In FY 1995, the R&D activities in each development field were focused on research of existing technologies. However, in some fields, the studies of the elementary technologies were commenced. Major results obtained will be summarized below.

2.1 Subtask 1: Investigation and study for evaluating and reviewing R&D

Besides investigation of a pilot plant of Phase II, the image of the total plan for WE-NET was prepared.

2.2 Subtask 2: Review and investigation for promoting international cooperation

(1) An international symposium on hydrogen was held to exchange technologies and information.
(2) Investigation on formation and long vision of the international network were prepared.

2.3 Subtask 3: Conceptual design of the total system

(1) The conceptual design of the total system was made with liquid hydrogen to estimate facility cost and economy on a trial basis. The system flow diagram used is shown in Fig. 2.
(2) In order to evaluate the effects obtained by introducing the hydrogen energy on the bases of world-level, national-level, and city-level, modification and coordination of the existing simulation model were carried out.
(3) Collection and selection of accident cases and improvement and development of the analysis code were carried out for safety evaluation.

2.4 Subtask 4: Development of hydrogen production technologies

On the basis of four methods of chemical plating, hot pressing, porous sintered electrode, and zero gap, which are different in electrode bonding method, small capacity laboratory cell evaluation facility with a capacity of 50 cm2 was assembled to carry out performance evaluation. As a result, an energy efficiency of 90% was achieved at a current density of 1 A/cm2 which was a target value. For investigation for scaling-up, an experiment using a laboratory cell with a capacity of 200 cm2 was commenced.

2.5 Subtask 5: Development of cryogenic materials technologies

(1) Development of large-capacity hydrogen liquefaction facilities
Process investigation were carried out roughly on the Neon Brayton cycle as the liquefaction cycle for hydrogen and also the improvement of the efficiency of the major equipment was studied.

(2) Development of liquid hydrogen transportation tanker
A trial design, thermal insulating method, and supporting method were investigated on a tanker-carrying sphere-shaped tank and square-shaped tank each with a capacity of 200,000 m3. The investigated results on various insulating structures are shown in Table 2.

(3) Development of liquid hydrogen storage facilities
The basic system flow was investigated, and the conceptual design and thermal insulation structures of a tank with a capacity of 50,000 m3 were studied.

(4) Development of devices of common use
A survey was continuously carried out on large-capacity liquid hydrogen pumps, heat insulation piping, liquid hydrogen valves, and instrumentation facilities to abstract technical themes.

(5) Development of hydrogen absorbing alloys for small-scale transportation and storage system
Investigation was continued on magnesium alloys small in weight but large in hydrogen storage capacity as well as on the improvement effect of characteristics by nano-crystallization. In addition, the systems for stationary use and hydrogen automobile were commenced.

2.6 Subtask 6: Development of cryogenic materials technologies

Out of typical existing structural materials, stainless steels, SUS304L and SUS316L, and aluminum alloy A5083 were studied to continuously collect the data concerning mechanical properties as well as the hydrogen embrittlement at the helium temperature level. The specifications of material test equipment under the liquid hydrogen environment were also studied.

2.7 Subtask 7: Feasibility study on utilization of hydrogen energy

The present states of various hydrogen utilization technologies were studied and investigation was carried out on the supply system from the perspective of application.

2.8 Subtask 8: Development of hydrogen-combustion turbine

(1) Study for an optimum system for hydrogen-combustion turbine
The detailed studies were carried out for the presented cycles and their selection was tried. It was confirmed that all of three types as shown in Fig. 3 attain an electric power generation efficiency of 60%.

(2) Development of combustion control technologies
A combustion test using a small-scale burner and the full scaled model of a combustor was carried out to analyze wall temperature distribution and prepare the conceptual design of the combustor.

(3) Development of turbine blades, rotors, and other major components
On the basis of the basic heat balance (Gratz cycle), the frame of a high temperature turbine was designed. The conceptual design of rotor and stationary blades cooled for high temperature steam of 1,700ｰC class was made.

(4) Development of major auxiliary equipment
The heat transfer properties of high temperature heat exchangers were investigated to study their configurations and major dimensions at a demonstration equipment level. The feasibility of an oxygen production equipment using the cryogenic energy of liquid hydrogen was studied.

(5) Development of super-pyrogenic materials
Heat resisting alloys, intermetallic compounds, ceramics matrix composites and C/C composites which are promising as materials for super-pyrogenic temperature components such as blades of hydrogen combustion-turbine were tested and evaluated for their basic characteristics (physical, chemical, and mechanical properties).

2.9 Subtask 9: Study of innovative and leading technologies

In order to find innovative and leading technologies, research and investigation were carried out, and at the same time, the evaluation procedures of these technologies were determined.

3. Future development

Research, basic investigation, study of elementary technologies, and other investigations will be carried out continuously to FY 1995 to obtain necessary information for the optimum design of the total system, in order to confirm establishment of technologies required to design and construct a pilot plant.

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