WE-NET : THE NATIONAL HYDROGEN PROGRAM OF JAPAN VISION AND STATUS

KAZUKIYO OKANO
WE-NET Office
Engineering Advancement Association of Japan
CYD Bldg. 1-4-6, Nishi-Shinbashi, Minato-Ku,
Tokyo, 105 Japan

abstract

The WE-NET (World Energy Network) Program is a project that has been conducted by the New Energy and Industrial Technology Development Organization (NEDO) since FY1993 as part of the Japanese government's New Sunshine Program. The WE-NET Program aims to secure new energy sources and maintain the global environment in good condition by building an international network for hydrogen energy. Over the past four years, steady progress has been made and superb results obtained in R&D activities of each subtask on hydrogen production, transportation, storage and utilization systems.

1. Introduction

The WE-NET Program is a large-scale project aimed to give comprehensive solutions to two global problems of energy and environment. With the goal of laying the foundation for building a large-scale hydrogen energy network system, research and development work have been carrying out since FY1993. The overall system comprises three basic processes, hydrogen production, hydrogen transportation, storage and hydrogen utilization. Besides technology development total system design and analysis have been conducted. The program is being proceeded in cooperation with government, industry and academia.

2. Japan's Response to Protect the Global Environment

Developing measures to prevent global warming accompanying the increase in energy demand is a common issue faced by countries throughout the world. Although the world energy demand is predicted to rise, the increase in Asia is expected to be particularly striking. In its midterm report issued in June 1995, the Advisory Committee for Energy of the Ministry of International Trade and Industry (MITI) predicts that energy demand in 2010 will be double the 1992 volume. The CO2 emissions volume in the Asia region will also approximately double accompanying this rising energy demand, and Asia's CO2 emissions will come to account for 25 percent of the world volume. Refer to Figure 1.
To control air pollutant and CO2 emissions, Japan drafted the action program to arrest global warming in 1990 and has been endeavoring to develop new energy technologies.
The WE-NET program was started in FY1993 as a large scale international project of the New Sunshine Program, and MITI and NEDO commenced a long-term technological development project to create an international network for hydrogen energy.

3. Outline of the World Energy Network

The WE-NET program proposes to convert hydropower and other renewable energy, that are available in abundant quantities and not being used at the present in various part of the world, into hydrogen through water electrolysis and other appropriate processes, and transport hydrogen to the countries in demand. The transportation of hydrogen would be carried out by ships in the form of liquefied hydrogen. Hydrogen would be stored in the energy consumption areas and used to generate electricity by means of hydrogen combustion turbines and in other forms of application such as hydrogen vehicles and fuel cells etc.
The WE-NET program proposes to carry out international cooperation for developing the core technologies required to build the international network making it possible to materialize the energy utilization scheme described above, as well as the optimum design of the network system.
Should a clean secondary energy system of this kind utilizing hydrogen is realized, the special and chronological imbalance between the supply and demand of energy in global scale could be eliminated and it would be possible to expect the simultaneous solution of both energy problem and environmental problem. Goals of the WE-NET program are as follows.
ETo establish global, clean-energy network using hydrogen produced by renewable energies
ETo improve air quality and reduce CO2 emissions
ETo assure adequate future energy and fuel sources

4. WE-NET Program Structure

The project term is divided into three phases extending over a 28 year period from 1993 to 2020. Phase 1 of the project is from FY1993 to FY1998. An evaluation has been done at the end of FY1996 (March 1997) on the R&D results up to that date. R&D plan for FY1997 and thereafter will then be drawn up based on the evaluation. The whole program is financially supported by MITI / NEDO. The total budget is 300 billion yen (US2.4 billion) for 28 years. The budget of Phase 1 period is about 10 billion yen.

5. Organization of the WE-NET Program

Under the WE-NET program, a wide range of R&D activities is being conducted on every aspect of hydrogen energy technologies by pooling the efforts of Japanese industry, government, and academia and receiving the cooperation of research institutes and corporations in overseas countries . Under the guidance of the Agency of Industrial Science and Technology (AIST) of MITI, NEDO oversees the overall WE-NET program while the individual R&D subtasks are supervised by other organizations that serve as subtask managers. A committee is set up for each subtask to determine R&D topics, follow research progress, and evaluate research results. These committees are composed of the subtask managers as well as representatives from universities, national research institutes, corporations and organizations. The actual R&D work is performed by leading Japanese corporations in various industries as well as foreign participants. The organization and the subtasks for the project are outlined in Figure 2 and 3.

6.1 SYSTEM ANALYSIS

6.1.1 Conceptual Design of the Total Systems

The total system, the efficiency, the economy and the technical feasibility have been studied and evaluated. In case of hydrogen production using 1000MW electricity and hydrogen transportation of 5000km by a tanker, energy losses in the processes of hydrogen production, liquefaction, transportation and storage are about 30%. The total system efficiency which is output electric power from hydrogen combustion turbine by input hydraulic electric power is 37.7%. System studies on methanol and ammonia as an energy carrier, and comparison of those systems with hydrogen system were conducted.

6.1.2 Analytical Evaluation on Introduction of Hydrogen Energy

Analytical evaluation on introduction of hydrogen energy using modified GREEN model was conducted for the global market and Japanese market.

6.1.3 Other Assessment

National level and city level energy estimation and assessment, and safety measures and assessment have being conducted.

6.2 HYDROGEN PRODUCTION

High efficiency and large scale water electrolyser plant using solid polymer electrolytes are being developed. Target of 90% energy efficiency at 1A/cm2 was achieved by 50 and 200 cm2 test cells. Development of 2500cm2 large size cells has been started from FY1997 and finally 10000cm2 class cells will be developed. Chemical plating method and hot press method will be applied for production of large sized and high performance cells. Besides these cell development higher temperature polymer membrane has being developed to raise energy conversion efficiency of water electrolysis.

6.3 HYDROGEN TRANSPORTATION AND STORAGE

6.3.1 Hydrogen Liquefaction Plant

Hydrogen Claude and Helium Brayton cycles have being studied for the 300t/day liquefaction plant of over 40% process efficiency. Research and development of major components of a plant such as a compressor and an expansion turbine will be conducted in the next stage of the development.

6.3.2 Liquid Hydrogen Tanker

Conceptual design of 200,000m3 tankers with prismatic tanks and spherical tanks was carried out. Testing of insulation structures will be started to know the characteristics of the tank insulation at cryogenic temperature from FY1997. Specification of a tanker is shown in Table 1. TABLE 1. Specification of a liquid hydrogen tanker

Tank capacity : 200,000 m3

Ship length : 290-320 m

Ship width : 48-56m

Ship speed : 25 knots

Type of ship : Twin hull ship

B.O.G. rate : 0.2-0.4%

6.3.3 Liquid Hydrogen Storage

Development of the liquid hydrogen storage equipment comprises the design of the entire system for storage and research of the storage equipment. The conceptual design of the 50,000m3 storage tanks such as spherical, cylindrical, and in-ground tanks was carried out. A test equipment for insulation structures will be installed in FY1997 and the testing of insulation structures will be conducted at liquid hydrogen temperature. Also liquid hydrogen pumps will be developed for handling of liquid hydrogen for storage tanks and hydrogen combustion turbines.

6.3.4 Metal Hydrides

Application of metal hydrides for transportation and stationary storage have been studied, and development of higher performance alloys has been started from FY1997 to achieve the target of 3wt% absorbing capacity at 100C.

6.4 CRYOGENIC MATERIALS

A mechanical test equipment which can be used for evaluation of mechanical properties and hydrogen embrittlement of structural materials in liquid hydrogen atmosphere was installed. Material tests for mother plate and weld metal of stainless steel and aluminum alloy have been started from FY1997.

6.5 HYDROGEN UTILIZATION

The following hydrogen utilization systems are being studied and evaluated to propose the technology development and demonstration.

6.5.1 Hydrogen/Oxygen Fueled Diesel Cogeneration Systems

Zero-emission closed cycle diesel engine cogeneration systems of 600~1000kW were studied. The system is perfectly clean and high electrical efficiency of 45~50% (LHV) is expected. Development for main components of a diesel engine such as a hydrogen injector and an igniter has been started.

6.5.2 Hydrogen Vehicles

Hydrogen engine hybrid system for a wagon and PEM fuel cell hybrid system for a bus have being studied. Conceptual design of these vehicles will be conducted till the end of FY1998 using metal hydrides storage system for a wagon and liquid hydrogen tank system for a fuel cell bus.

6.5.3 Fuel Cells

The following PEM fuel cell power plants were studied.
(1) Hydrogen/Oxygen fueled 5000kW dispersed power plant
(2) Hydrogen/Air fueled 200kW onsite power plant
(3) 20kW power system for vehicles
In case of 5000kW PEM fuel cell power plant, very high electrical efficiency of 56% (HHV) can be achieved. Conceptual design of these plants will be conducted till the end of FY1998.

6.5.4 Oxygen Production Systems

Small scale oxygen production systems utilizing cryogenic heat of liquid hydrogen have being studied for diesel cogeneration systems and 5000kW fuel cell power plant. Air separation plant method (Cryogenic method), PSA-combined general condensation method and V-PSA method were examined to evaluate system efficiency, and economics will be studied in FY1997.

6.5.5 Hydrogen Distribution Systems

A medium-size city in Japan was selected as the candidate model city. The energy supply and demand situation in the city was investigated in the case of entire energy demand, and the feasibility of converting hydrogen energy in the city was analyzed. The necessary infrastructure for a hydrogen distribution and supply systems in a city will be examined, and the design of hydrogen storage systems and refueling systems will be conducted.

6.6 HYDROGEN COMBUSTION TURBINES

Hydrogen combustion turbine system will be one of the most effective system for large-scale and centralized power generation. The evaluation to select the optimum turbine cycle and conceptual design of a 500MW power generating plant were conducted. Electrical efficiency was proved about 61% (HHV), and gas inlet temperature is 1700C. R&D subjects in Phase 1 period for developing elemental technologies are as follows.
(1) Combustion control technology
(2) Turbine blades, rotors and other major components
(3) Major auxiliary equipment
(4) Super-pyrogenic materials

6.7 STUDY OF INNOVATIVE AND LEADING TECHNOLOGIES

This project aims to study, review and assess innovative and leading technologies as well as existing technologies in order to identify promising technologies and to propose them for addition to the WE-NET project as new R&D areas or subjects. Subtask 9 is always open for new proposals.

7. OUTLOOK OF THE WE-NET PROGRAM

The WE-NET Program is an effective plan to prevent air pollution and global warming. However to achieve this program the understanding and support of countries throughout the world, government and industry partnership to introduce hydrogen, long term government support of hydrogen technology commercialization and reliable technology development by industry are indispensable for the success of this program. The international conference on climate change (COP3) will be held in Kyoto Japan on coming DecemberAand the target of CO2 reduction will be decided at the conference. That will be a potential significant driver for the development of CO2-free clean energy systems. The WE-NET Program should be promoted vigorously with the international cooperation as one step in overcoming problems of global environment.

Reference
(1) New Energy and industrial Development Organization (NEDO) (1997), The midterm Report of the WE-NET program Phase 1.