Industrial Prospective for Hydrogen Utilization

- Safety Aspect -

10 September 2005

K.Takeno

Mitsubishi Heavy Industries, Ltd.

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

Natural Energy (Wind, Solar, Biomass)

Steam Reformation

Gas Engine

(η ～44%)

Storage of

Hydrogen

Nuclear Energy

H2

Natural Gas

Fossil Energy (Natural Gas, Oil)

Electrolysis of Water

Electricity

Membrane Reformation

Direct Production from Water

Gas Turbine

(η ～41%)

PEFC

(η ～60%)

Special Use

(rocket etc)

H2

As the final conversion device from hydrogen, PEFC has highest efficiency

On-site hydrogen station

Role of Hydrogen in Natural Energy System

Wind Power

Methanol(Storage)

Electricity

DC/AC

Power Source

O2

H2

DC/AC

Solar Cell

Biomass Gasificationto produce H2 and

CO

Solid Polymer Water Electrolysis

Rechargeable battery

Polymer Electrolyte Fuel Cell

Solid Oxide Fuel Cell

If biomass gasification is combined, performance becomes higher (oxygen from electrolysis can be utilized and carbon from biomass can be fixed to liquid fuel).

Engine

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

Research on Safety

WindBuoyancy

Flow & Diffusion

Mixing of air with H2

EXPLOSION orEXPLOSION orDiffusion FlameDiffusion Flame

Leak of LH2 (Liquid) or GH2 (High-PressurizedGas)

H2Tank

LH2 : Evaporation Diffusion GH2 : Diffusion

Flammable H2/Air Mixture

Pressure WaveRadiation

Research on Safety (continued)

# Evaporation of LH2

# Diffusion of GH2

# Immediate Ignition ⇒ 　 Diffusion Flame

# Delayed Ignition ⇒ 　 Explosion# Spread of Flammable Mixture

# Scale of Diffusion Flame

# Propagation of Pressure Wave

# Radiation from High Temp. Steam

Hypothesis Accidents

Experiments

Computer Simulation

Evaluation of Safety

(Risk Analysis)

Probability study

Safety Regulation

Research on Safety (continued)

21m 3.6m

100

1000

10000

100000

0.0001 0.001 0.01 0.1 1 10 M (kg/ s)流量

Lf

(m

m)

火炎

長

10.0 5.02.0 1.170.53 0.32

噴出口径(mm)

16700･M0.5

Flow Rate of H2 Gas

Len

gth

of

Fla

me

Nozzle diam.

High-pressure H2 flame（ d=10mm， P=28MPa）(Visualized by Na addition)

Lig=31.5mm

Schuliren photo image （ d=1mm ， P=20MPa ）(Flame is stabilized behind shock wave)

][:6.71/

2.399/48.0

max

5.0

MPaPPdr

PdL

f

f

Correlation of flame scale Lf: flame length rfmax: maximum flame diameter d: nozzle (opening) diameterThis formula is used for the Japanese regulation of hydrogen safety.

Research on Safety (continued)

75 ～ 90m/s

Large scale (300m3) explosion experiment, conducted by IAE / SRI(H2 (30%) / Air mixture)

Velocity of flame propagation

[Pa]

Typical result on the atmospheric diffusion of leaked H2 at an assumed hydrogen supply station.(40MPa-400m3, d=10mm opening, t=3s)

Pressure distribution at t=100ms

Natural Energy (Wind, Solar, Biomass)

Steam Reformation

Gas Engine

(η ～43%)

Storage of

Hydrogen

Nuclear Energy

H2

Natural Gas

Fossil Energy (Natural Gas, Oil)

Electrolysis of Water

Electricity

Membrane Reformation

Direct Production from Water

Gas Turbine

(η ～39%)

PEFC

(η ～60%)

Special Use

(rocket etc)

H2

Total Efficiency from NG

via H2 direct use ～29% ～42%

～27% ～39%

～42%

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.

Atomic Furnace

Ｈ２

Reformation

CH4

CH4＋ H2O+heat→CO+3H2

Membrane

Catarist

City gas Steam

Heat Membrane

Catarist

Hydrogen

Membrane　 Reformer

This can be operated at low temperature (～ 550 ) and conversion efficiency is high (℃ ～ 75%)