WE-NET : THE NATIONAL HYDROGEN PROJECT OF JAPAN, ITS VISION AND STATUSToshihiro HiraiWE-NET Office Engineering Advancement Association of Japan CYD Bldg. 1-4-6, Nishi-Shinbashi, Minato-Ku, Tokyo, 105 Japan
1. IntroductionJapanese government has started "The New Sunshine Program" in 1993, which aims at developing innovative technologies to create sustainable economic growth while solving energy and environmental problems. One of the new and important projects in this program is "International Clean Energy Technology Utilizing Hydrogen (World Energy Network; WE-NET)".Goals of the WE-NET project consist of developing technologies necessary to construct a worldwide hydrogen energy network, including production, transportation, storage and utilization. The electric power to produce hydrogen will be supplied by renewable energies, such as hydroelectric power, photovoltaic cells, etc. The project is conducted by The New Energy and Industrial Technology Development Organization (NEDO), and carried out by nine Subtasks. It extends twenty eight (28) years from 1993 until 2020, of which term is divided into three phases. In phase I (FY1993-1998), we have been studying on the conceptual designs of the total system, large-scale liquefaction plants, liquid hydrogen tankers, liquid hydrogen storage facilities and utilization facilities. Along with the design studies we have started elementary studies on several basic technologies, such as water electrolysis using solid polymer electrolyte, a hydrogen combustion turbine, cryogenic materials, hydrogen absorbing alloys. 2. OUTLINE OF THE WE-NET PROJECT2.1 Schedule of the ProjectThe project term is divided into three phases extending over twenty eight (28) years from year of 1993 to 2020. A goal of each phase is as follows:Phase I 1993-1998 Conceptual design of the total system / Basic R&D of elementary technologies Phase II 1999-(2003)* Construction and operation of small scale plants Phase III (2004)*-2020 Construction of pilot system in worldwide scale * tentatively scheduled 2.2 FundingThe whole project is funded by The Agency of Industrial Science and Technology (AIST), Ministry of International Trade and Industry (MITI).The total budget is expected to be approximately 300 billion yen (ca. three billion US dollar) for total period of the project of twenty eight years. The budget for each fiscal year in Phase I was as follows:
(million yen) 2.3 OrganizationNine Subtask (ST) committees are organized in order to promote the project. The whole project is conducted by The New Energy and Industrial Technology Development Organization (NEDO).
3. TARGETS OF TECHNOLOGY DEVELOPMENTWe expect 1,000MW power stations as a main utilization facility in the project. 1,200 t/d of liquid hydrogen will be necessary to operate the station. In order to supply enough liquid hydrogen to the station every ten days via service route of twenty days voyage, tow tanker ships having a capacity of 200,000 m3 or 14,000t will be required.According to these assumptions, targets of main technologies were evaluated and settled as follows: H2 production: Polymer electrolyte water electrolysis having efficiency over 90% at the current density of 1-3A/cm2 H2 Liquefaction: 300 t/d plant having efficiency over 40% L H2 Transportation: 200,000 m3 (14,000t) LH2 tankers L H2 Storage: 50,000 m3 LH2 storage tanks H2 combustion turbine: 500MW output power with efficiency of 60% 4. PRESENT STATUS OF THE PROJECT4.1 Total System EvaluationTotal network system was evaluated in terms of efficiency, economy, technical feasibility, safety, etc., including methanol and ammonium as well as liquid hydrogen as transportation media. According to the evaluation results, liquid hydrogen system will be most feasible as the hydrogen energy system in the future, if we take account of the advancement on liquid hydrogen technologies we are developing and expecting.4.2 Hydrogen ProductionSmall cells of 50cm2 and 200cm2 in size having polymer electrolyte were prepared and tested. Four different types of cell configurations were evaluated, and two promising types were selected for large cell tests, in which 0.25m x 1m sized cells will be prepared and evaluated.4.3 Hydrogen LiquefactionFive different processes were studied for the large scale plant having a capacity of 300t/d , which is ten times larger than the biggest existing plant. Two promising process, Hydrogen Claude Cycle and Helium Brayton Cycle, were selected for the further studies. Elementary development on key components is being planed. A centrifugal compressor and an expansion turbine are estimated to be the most important elements to be developed for the large scale plant.4.4 Liquid Hydrogen TankerConceptual design of tanker ships having a capacity of 200,000m3 were made. Two types of tanks, spherical and prismatic, were designed, and possible insulation structures were studied, which included very thick polyurethane foam, vacuum panels and super insulation as insulating materials around the tank. Basic specification of the tanker design are as follows:
Hull structure: Double / Single 4.5 Liquid Hydrogen Storage TankConceptual design of four types of tanks were made including underground storage system. Target boil-off gas rate of tanks was settled to be 0.1%/d for the study.
Type 1: Flat-bottomed cylindrical & Spherical / Vacuum powder insulation
Study of the above four types of tanks provided a result that every tank has a possibility. In this year we are planning to install a test equipment which can evaluate insulation performances of candidate insulation structures under the condition of liquid hydrogen temperature. 4.6 Metal Hydrides for Small Volume Storage and TransportationAdvanced technologies on metal hydrides were reviewed and estimated their potentiality in localized hydrogen storage systems. It was concluded that a high performance metal hydride should be developed in the project. Development studies were substantially started this year. A target of our study is developing a metal hydride possessing the following properties:
Absorption capacity : 3wt%
4.7 Hydrogen Combustion TurbineHydrogen combustion turbine is expected to be the most effective equipment for a large scale power generation system, of which efficiency could be 60% because of very high temperature, 1700degree in our study, at the inlet of the turbine. The following developments are being conducted:
・ System evaluation In the system evaluation, three cycles, New Rankine Cycle, Topping Regenerative Cycle and Rankine Cycle with Reheat and Recuperation, were selected as promising processes and for further studies. 4.8 Utilization of HydrogenOther than main usage at the power station with hydrogen combustion turbines, several potential applications were being evaluated. The following applications were revealed to be promising and selected for further studies:
・ Diesel cogeneration system 4.9 Innovative and Leading TechnologiesAs the project extends very long term of time, new and innovative technologies might be developed during the term and could be beneficial to the project. Subtask 9 watches such technologies worldwide, and is open for proposals of developing new technologies for the project.5. CONCLUSIONSThe WE-NET project could be very effective globally preventing air pollution and air warming. However, the project will not be successful by efforts of Japan alone. Cooperation and support of countries throughout the world are indispensable for the success of the project and the protection of the global environment.References
1. 1996 Annual Summary Report on WE-NET, NEDO (1997) |
