Industrial Prospective for Hydrogen Utilization - Safety Aspect - 10 September 2005 K.Takeno Mitsubishi Heavy Industries, Ltd. 添付-2

MHI’s Activities for Hydrogen MHI, general machinery and power plant maker, focuses on two aspects concerning hydrogen. 1. When hydrogen is used as the alternative energy resources from fossil energy, we should provide the high-quality and high-efficiency devices for hydrogen production, storage, and utilization. 2. Utilization as the media of energy chain among natural reproducible energy (wind, solar, geothermal, water, biomass, etc.), and nuclear energy.

Energy Chain through Hydrogen On-site hydrogen station As the final conversion device from hydrogen, PEFC has highest efficiency

Role of Hydrogen in Natural Energy System Electricity DC/AC DC/AC H2 Wind Power O2 Solid Polymer Water Electrolysis Polymer Electrolyte Fuel Cell Solar Cell Rechargeable battery Methanol (Storage) Solid Oxide Fuel Cell Engine Biomass Gasification to produce H2 and CO Power Source If biomass gasification is combined, performance becomes higher (oxygen from electrolysis can be utilized and carbon from biomass can be fixed to liquid fuel).

Introduction of Future Plan (RERE System) ＊RERE(Renewable Energy based Rural Electrification)

Research on Safety EXPLOSION or Diffusion Flame Wind Buoyancy Mixing of air with H2 Buoyancy Flow & Diffusion LH2 : Evaporation Diffusion GH2 : Diffusion Flammable H2/Air Mixture EXPLOSION or Diffusion Flame H2 Tank Pressure Wave Radiation Leak of LH2 (Liquid) or GH2 (High-PressurizedGas)

Research on Safety (continued) Hypothesis Accidents Probability study # Evaporation of LH2 # Diffusion of GH2 # Immediate Ignition ⇒　Diffusion Flame # Delayed Ignition ⇒　Explosion Experiments Computer Simulation # Spread of Flammable Mixture # Scale of Diffusion Flame # Propagation of Pressure Wave # Radiation from High Temp. Steam Evaluation of Safety (Risk Analysis) Safety Regulation

Research on Safety (continued) High-pressure H2 flame（d=10mm，P=28MPa） (Visualized by Na addition) Correlation of flame scale Lf: flame length rfmax: maximum flame diameter d: nozzle (opening) diameter This formula is used for the Japanese regulation of hydrogen safety. Schuliren photo image（d=1mm，P=20MPa） (Flame is stabilized behind shock wave)

Research on Safety (continued) Large scale (300m3) explosion experiment, conducted by IAE / SRI (H2 (30%) / Air mixture) Typical result on the atmospheric diffusion of leaked H2 at an assumed hydrogen supply station. (40MPa-400m3, d=10mm opening, t=3s) 75～90m/s [Pa] Velocity of flame propagation Pressure distribution at t=100ms

Principal Conclusion and Perspectives # Problem seems to be the energy efficiency. It is difficult to overcome the direct use of natural gas to gas engine or turbine. # At the standpoint of industrial researcher, it is the urgent demand to raise the conversion efficiency from NG or nuclear energy to hydrogen. Specially, MHI expects membrane reformer, which can be operated at low temperature (～550℃) and conversion efficiency is high (～75%). # From CO2 problem, the use of natural renewable energy is expanding globally. If hydrogen is the core of energy flow, many kinds of natural energy can be combined.

Membrane Reformer CH4＋H2O+heat→CO+3H2 This can be operated at low temperature (～550℃) and conversion efficiency is high (～75%)