On R&D of Hydrogen Combustion Turbine in WE-NET Project

Professor, The Institute of Industrial Science, The University of Tokyo*
Director, The Gas Turbine Society of Japan
Director, The Japan Federation of Engineering Societies

This paper describes a brief introduction of the project entitled International Clean Energy Network Using Hydrogen Conversion (WE-NET: World Energy Network) supported by Agency of Industrial Science and Technology in the Ministry of International Trade and Industry (MITI). Especially, R&D of a hydrogen combustion turbine is introduced.

Key Words: Hydrogen Combustion, WE-NET, Gas Turbine, and Combined Cycle

1. Introduction

As the dawn of a new century nears, it has become a global priority that we collectively discuss and resolve such vital issues as providing affordable power, developing diverse energy resources, and protecting the global environment. As you are aware, "COP3" -- The Conference of Third Parties -- was held last December in Kyoto, Japan. A key goal of that conference was to conclude a legally binding international agreement regarding specific targets for emission-control levels.
Toward this goal, engineers and researchers are continually seeking diverse ways to make power generating systems more efficient, improve system reliability, and reduce emissions from plants that burn fossil fuels.
Energy problems are briefly considered as follows. Fossil fuels do not remain so much on the earth as the human being will be able to use them forever. For example, an economically available term of crude oil is estimated as about 50 years. Furthermore, crude oil and natural gas are not universally distributed on the earth. Therefore, we have to use clean energies much more, such as solar energy, wind power, hydropower, geothermal energy and so on. Solar energy and wind power, however, are not easily utilized because they do not exist continuously and their energy densities are not sufficient to use economically. Hydropower has great amounts in the world and it is considered as the most important renewable source for electricity in use in the world.
For protecting global warming, it is necessary to reduce emission of carbon dioxides, and then we ultimately have to select hydrogen as a fuel. On this background, MITI planned the WE-NET project for 28 years term. It aims at contribution to solving global environmental problems by means of large-scale and effective utilization of clean and renewable energies.
Hydrogen, however, does not exist naturally then has to be produced by using clean and renewable energies, for example, hydropower or solar energy. Therefore, it is necessary to establish a worldwide energy network for producing and transporting hydrogen.

2. Outline of WE-NET project

The purpose of the project is to establish technologies of introducing an international energy network such as hydrogen production, conversion of hydrogen, transportation, storage, and power generation. WE-NET project has been planned to be conducted in three phase terms. In Phase I, a wide range of basic technologies on hydrogen has been studied as follows. In Phase II of the overall plan, technologies needed to construct an international demonstration system will be established, and in Phase III of the overall plan, a demonstration system will be constructed through international cooperation.
In order to develop core elementary technologies, Phase I of WE-NET scheduled for six years from FY 1993. For the purpose, the project has been conducted by following 9 groups in Phase I.
Subtask 1 is named as 'Investigation and study for evaluation and reviewing R&D'. In this task, we conduct a constant overall coordination of the project on each individual technology development such as hydrogen production, transportation and storage, and hydrogen utilization. Moreover, we evaluate developed results to optimize a program schedule.
In addition, we will study tendencies of technology development in Japan and abroad to reflect them upon the future work of the project programs.
Subtask 2 is named as 'Review and investigation for promoting international cooperation'. We perform periodic information exchanges with international organizations and relating nations in order to establish a worldwide system. Subtask 3 is named as 'Conceptual design of the total system'. We evaluate technologically and economically a conceptual design of the total system that consists of hydrogen production using clean and renewable energies, transportation and storage, and hydrogen utilization including power generation. Furthermore, we estimate effects of introduction of hydrogen system in a worldwide scale and an individual country scale, and develop safety measures and evaluation technologies.
Subtask 4 is named as 'Development of hydrogen production technology'. In Phase I, we investigate technologies to achieve large scaling-up and long life water electrolysis of solid polymer electrolyte, which is expected in high efficiency and high current density. Moreover, we develop elementary factors such as solid polymer electrolyte, anode and cathode catalysts, and materials for electrolyzer, and conduct bench scale tests in order to establish technologies necessary for a pilot plant.
Subtask 5 is named as 'Development of hydrogen transportation and storage technologies'. We work the following items regarding hydrogen production, transportation, and storage for getting data necessary to determine an optimum system of mass 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
(4) Development of devices for common use
(5) Development of hydrogen absorbing alloys for small-scale transporting and storage system
Subtask 6 is named as 'Development of cryogenic materials technology'. We obtain data on toughness, fatigue, and serration of structural materials at the temperature range of liquid hydrogen (20K). Moreover, we investigate structural materials useable in the liquid hydrogen environment including development of new materials, and study their proper welding method.
Subtask 7 is named as 'Feasibility study on utilization of hydrogen energy'. We investigate and study applicable technologies and demand of hydrogen in future in various fields, such as power generation, industry, transportation, and civil application, for various chemical materials of hydrogen gas, liquid hydrogen, and methanol. Thereafter, we clarify the merit and demerit of each technology. In addition, we evaluate application technologies of cryogenic energy of liquid hydrogen.
Subtask 8 is named as 'Development of a hydrogen combustion turbine'. In 5 subgroups, we study the following items of a hydrogen combustion turbine that is expected as an effectively utilizing technology of hydrogen because of its extraordinary high efficiency.
(1) Study of an optimum system for hydrogen combustion turbine
(2) Development of combustion control technology
(3) Development of turbine blades, rotor, and other major components
(4) Development of major auxiliary equipment
(5) Development of super heat-resisting materials
Subtask 9 is named as 'Study of innovative and leading technology'. WE-NET is a long-term project. We investigate and evaluate some innovative and leading technologies and states-of-art technologies to introduce promising technologies into WE-NET project.

3. Development of a hydrogen combustion turbine

R&D of a hydrogen combustion turbine is the most important subject in the WE-NET project. Hydrogen is considered as the quite expensive fuel because it does not exist naturally. Therefore, the power generating system of burning hydrogen with oxygen is required to realize much higher thermal efficiency. The target of the thermal efficiency is more than 60 % on basis of HHV. In order to achieve the targets, Subtask 8 has been studied by 5 subgroups mentioned above.
(1) Study of an optimum system for hydrogen combustion turbine
To realize such high thermal efficiency, we considered applying a combined cycle of gas turbine and steam turbine or a new Rankine cycle. Temperature at turbine inlet (TIT) has been planed to be 1,700 deg-C and efficiencies of elements have been requested quite high values, such as 89 % of adiabatic efficiency of compressor and 93 % of adiabatic efficiency of turbine.
This program was conducted by competition of three companies in Japan and USA. We discussed three conceptual systems proposed by them and chose 'topping regenerative cycle' as the optimum cycle at present. This task stopped after interim evaluation in FY 1996.
(2) Development of combustion control technology
Combustion of hydrogen and oxygen in inert gases such as steam is a key technology to realize a hydrogen combustion turbine. For the purpose, we are carrying some combustion tests by some types of small model combustor, such as annular type and can type, to clarify combustion characteristics.
We will obtain basic data regarding possible reduction of residual hydrogen and oxygen near the stoichiometric ratio, proper cooling and dilution structures of combustor wall, and measuring methods of temperature and concentrations of residual hydrogen and oxygen in exhaust gases from combustor.
(3) Development of turbine blades, rotor, and other major components
Blade cooling technology is one of the most important technologies to realize a high temperature turbine. Meanwhile, cooling technology of rotor disk and sealing technology at root of rotor blades are also quit important to achieve high thermal efficiency.
We are conducting tests for several types of blade cooling, such as film cooling, hybrid cooling (film cooling plus steam convection cooling), steam convection cooling, and steam cooling / water cooling.
(4) Development of major auxiliary equipment
It is important for us to establish technologies of highly effective utilization of cryogenic energy of liquid hydrogen for evaporation of liquid hydrogen and oxygen production system. We have studied two types of hydrogen-oxygen supply system.
We also perform conceptual design and study compactness and safety of some high temperature heat exchangers. (5) Development of super heat-resisting materials
For achievement of extraordinary highly efficient turbine, it is necessary to develop materials usable under super high temperature circumstances. It is also important to study machining technologies, property evaluation, and structural design application of the materials.
From those viewpoints, we have conducted the following studies.
(1) Development of advanced single-crystal super-alloy and materials for hybrid cooled blade
(2) Development of oxide dispersion strengthened (ODS) alloy and thermal barrier coating (TBC) for cooled vane (3) Development of inter-metallic compounds (IC) material
(4) Development of ceramic-matrix composite (CMC) material
(5) Development of multi-structure ceramic material and evaluation method of fracture behaviors at ultrahigh temperatures under mixed-mode conditions
(6) Development of 3-dimensional fiber-reinforced composite materials
(7) Development of experimental evaluation method for super heat-resisting materials

4. Conclusion

It is necessary for us to consume energies in order to live on the earth. Especially, demands of electric power become much larger because of easy availability, and consumption of energy increases necessarily. The electric power, however, cannot be easily stored and does not exist naturally. Therefore, we have to construct new systems of power generation and energy consumption for sustainable developments.
I hope WE-NET project will act an important role in problems of energy and global environment.


International clean Energy Network Using Hydrogen Conversion, 1996 Annual Summary Report on Results, NEDO WE-NET 96, March 1997