Capgemini-为什么在内燃机中燃烧氢气是减少二氧化碳排放的明智且经济的选择（英）-2023

WHY

BURNING

HYDROGEN

ININTERNAL

COMBUSTION

ENGINES

ISA

SMART

AND

AFFORDABLEOPTION

FOR

REDUCING

CO2EMISSIONSINTRODUCTIONTransporting

people

and

goods

accounts

for

nearly

20%

ofthe

world’s

CO2emissions.

Transportation

sectors,

such

asautomotive,

shipping

and

aerospace,

are

under

increasingpressure

to

decarbonise,

not

only

to

address

society’sexpectations,

but

also

to

meet

targets

set

by

the

EuropeanUnion.They

are

currently

not

appropriate

for

many

largercommercial

vehicles

such

as

trucks,

construction

machinery,and

agricultural

vehicles

–

as

well

as

long

distance

shippingand

naval

vessels

–

due

to

battery-specific

challenges

suchas

poor

gravimetric

energy

density

(ie

generating

enoughenergy

would

need

too

battery

much

weight),

and

thelength

of

time

it

takes

to

recharge.

Some

are

exploringhybrid

electrical

architecture,

using

hydrogen

to

power

fuelcells,

which

generate

electrical

power,known

as

a

Fuel

CellElectrical

Vehicle

(FCEV).Electrification

is

clearly

one

route

towards

decarbonisation,and

the

likely

winner

for

light

road

vehicles

and

privatecars.

But

batteries

have

limits

that

make

them

less

suited

toheavier

vehicles

that

needs

lots

of

energy,

or

vehicles

thatdo

not

have

reliable

access

to

a

chargepoint

or

which

needsignificant

autonomy.Batteries

also

have

limits

in

aviation.

There

is

no

reason

theycouldn’t

be

used

for

short

distance

ferries,

light

aircraft

flyingshort

to

medium

distances,

and

Electrical

Vertical

Take-Offand

Landing

vehicles

(EVTOLs)

–

in

fact

a

number

of

early-stage

electric

vehicles

exist

in

these

areas.

However,thepoor

gravimetric

energy

density

(MJ/kg)

of

current

batterytechnology

compared

to

other

energy

sources

meanselectrification

is

not

an

appropriate

solution

for

use

in

largercommercial

aircraft,

or

ships

that

must

remain

at

sea

for

longperiods

of

time.The

internal

combustion

engine

(ICE)

holds

many

advantages.It

burns

fuel,

which

is

easy

to

transport

and

distribute.

It

has100years

of

innovation

behind

it

to

optimize

transfer

ofenergy

from

fuel

to

propulsion.

When

that

fuel

is

fossil

fuel,the

combustion

engine

is

clearly

no

longer

viable.

But,

if

thefuel

was

green

hydrogen,

the

combustion

engine

would

be

aninteresting

solution

for

decarbonising

many

vehicles.This

paper

will

discuss

the

opportunities

from

repurposingICEs

for

hydrogen

and

the

engineering

challenges

tobe

overcome.It’s

also

likely

some

smaller

aircraft

could

be

FCEVs.

Again,though,

the

poor

volumetric

energy

density

of

hydrogen,even

at

liquid

stage,

means

the

technology

couldn’t

be

usedfor

anything

larger.Decarbonising

transport:

Electrification

is

not

the

onlyanswerIt’s

also

clear

that

new

type

of

hybrid

aircraft,

smaller

andslower

than

current

models,

which

mixes

electrical

andthermal

engines

using

SAF

(Sustainable

Aviation

Fuel)

offer

asolution

for

short

range

flight1.The

most

common

market

reaction

to

decarbonizingtransport

has

been

a

move

toward

electrification,

replacinginternal

combustion

engines

(ICEs)

with

electric

powertrains,making

batteries

as

a

sole

energy

source.

These

are

highlyefficient,

generate

no

’tailpipe

emissions’

and

can

be

100%clean

if

green

energy

is

used.

The

automotive

industry

inparticular

has

seen

a

significant

shift

toward

electric

vehicles(EVs),

largely

focused

on

personal

vehicles

and

some

buses.This

transformation

is

welcome.

However

batteries

have

theirlimits

and

are

not

a

panacea.2BurningHydrogenininternalcombustionengines:asmartandaffordableoptionforreducingCO2

emissionsTHE

POSSIBILITY

OFHYDROGEN

COMBUSTION

ENGINESElectrification

is

not

the

only

game

in

town.

Internalcombustion

engines

could

still

remain

relevant,

if

we

usethem

to

combust

hydrogen

rather

than

fossil

fuels.The

keyhere

is

the

formula

P.V

=

K.T

which

shows

thatthe

product

of

volume

V

and

pressure

P

is

proportional

totemperature

T.A

high

volumetric

energy

density,

due

to

long

carbon

chainsand

reasonable

gravimetric

energy

density,

means

fossilfuel

has

been

best-in-class

since

the

end

of

the

nineteenthcentury.

But

the

combustion

of

carbon

chains

generates

CO2,which

makes

it

worst-in-class

for

net

zero

goals.One

answer,then,

is

gaseous

hydrogen

held

under

higherpressure

to

reduce

volume.

This

is

the

current

solution

forroad

and

rail

vehicles,

where

1KG

of

compressed

hydrogen(CH2)at

700

bar

provides

~100kmof

autonomy.

Ships

haveslightly

more

flexibility

on

space,

but

safe

and

efficientstorage

is

still

needed

to

be

developed

which

can

hold

largeamounts

of

hydrogen

for

long

periods

of

time

–

making

thetrade-off

between

low

temperature

or

high

pressure

–

bothon

ships,

and

bunkering

at

ports.Today,advances

in

technology

mean

it’s

possible

to

convertICEs,

enabling

them

to

burn

hydrogen

instead

of

fossil

fuels.But

this

is

not

without

its

challenges.Hydrogen

fuel

tanksAviation

presents

different

challenges

as

there

are

physicalupper

limits

to

the

space

and

weight

it

can

carry

before

flightbecomes

impossible.

At

normal

atmospheric

pressure

andambient

temperature,

you

would

need

approximately

3,000litres

of

gaseous

hydrogen

to

achieve

the

same

amount

ofenergy

as

one

litre

of

kerosene

fuel.

The

only

viable

solutionfor

storing

hydrogen

–

whether

for

fuel

cells,

or

to

powerturbo-propulsion

and

turbo

fans

via

combustion

–

is

to

use

10bar

pressure

and

reduce

the

temperature

to

-253ºC,

wherehydrogen

turns

from

a

gas

to

a

liquid,

increasing

its

energydensity.The

first

challenge

is

to

address

the

issue

of

low

volumetricenergy

density

when

storing

hydrogen

in

a

vehicle.

Althoughhydrogen

has

good

gravimetric

energy,

meaning

you

get

lotsof

energy

per

kilogram

burned,

it

has

poor

volumetric

density,ie

each

kilogram

takes

up

a

lot

more

space

than

a

kilogramof

petrol

or

diesel.

That

would

mean

a

vehicle

would

need

alarge,

heavy

tank

to

store

enough

hydrogen

fuel

to

powerthe

equivalent

driving

range

of

a

fossil

fuel

engine.

(Chart

1shows

the

difference

between

CH2

(compressed

hydrogen)/LH2

(liquid

hydrogen)

when

stored

or

not).That

would

still

be

limited

to

regional

aircraft

due

to

addedweight

even

under

optimal

conditions.

Long

range

will

needto

use

SAF.CHART

1:12108Volumetric

versusgravimetric

fuels

challenges(sources:

Mdpi,

Researchgate)HFO/VLSFODieselMGOGasolineJet

fuelAAvgasLPG

ButaneLPG

PropaneLNGEthanolNotes:

Avgas=

aviation

gasoline;

CH2=hydrogen

compressed

at

70MPa;

CNG

=natural

gas

compressed

at

25

MPa;

DME=

dimethyl

ether;

HFO/VLSFO

=

heavyfuel

oil/very

low

sulphur

fuel

oil;

LH2

=liquefied

hydrogen;

Li-ion

=

lithium-ionbattery;

LNG

=

liquefied

natural

gas;LPG

=

liquefied

petroleum

gas;

Stored6DMEMethanol4Stored

LNGAmmoniaCNGCNG

=

Type

IV

tank

at

250

bar;

StoredCH2=

best

available

CH2

tanks

at70LH22Stored

CNGStored

LH2Stored

CH2MPa;

Stored

LH2

=

current

small-scaleCH2LH2

on-board

tanks;

Stored

LNG

=small-scale

storage

at

cryogenicconditionsl

MGO

=

maritime

gasoil.Li-ionSupercapacitor005101520253035Numbers

are

expressed

on

a

lowerheating

value

(LHV)

basis.

Weight

ofthe

storage

equipment

is

included.Specific

energy

(kWh/kg)3BurningHydrogenininternalcombustionengines:asmartandaffordableoptionforreducingCO2

emissionsAdapting

ICEs

for

burning

hydrogenThe

specific

power

limitation

can

be

eliminated

viaappropriate

injection

devices

(high

pressure

directinjection)

and

air

boosting

with

oxygen

(addition

ofa

compressor

or

a

turbocharger).

Together

this

canproduce

very

high

efficiency

motors

(above

40%),whichcan

exceed

even

the

best

diesel

engines.Given

the

maturity

of

thermal

engine

technology,

burninghydrogen

in

an

ICE

is

an

interesting

option,

both

from

atechnical

and

an

economic

standpoint,

especially

in

vehiclesthat

are

hard

to

electrify.Nevertheless,

some

technical

challenges

must

be

overcome.For

instance:»

Removing

risk

of

self-ignition:

Hydrogen

is

verysensitive

to

self-ignition

and

backfire

phenomena

(auto-ignition

in

the

intake

manifold).

In

addition,

the

enginemust

be

clean,

in

particular

free

of

carbon

depositswhich,

in

turn,

could

cause

self-ignition.

It

is

to

remedythese

drawbacks

that

the

rotary

engine

was

adoptedby

the

Japanese

firm

Mazda

during

the

development

ofits

hydrogen-powered

vehicles

at

internal

combustion,in

1991.•

Developing

and

adapting

current

ICE

technologies

tohydrogen,

while

maintaining

a

reasonable

cost

for

themotor•

Upgrading

pollution

control

systems

to

manage

the

smallamounts

of

NOx

emissions

from

hydrogenTo

explore

this

further,

we

should

consider

piston-drivenICEs

for

motor

vehicles

and

turbine-driven

ICEs

for

aircraft.Hydrogen

combustion

for

ships

is

likely

to

follow

a

modelof

upgrading

existing

combustion

engines,

first

for

dualfuels

and

eventually

hydrogen

or

ammonia.

All

face

similarchallenges

which

are

discussed

below.»

NOx

emission

control

requires

precise

combustionprocess

management.

NOx

is

generated

at

veryhigh

temperature

when

hydrogen

combustionhappens

in

the

presence

of

a

lot

ofair.Wewant

toavoid

an

optimized

lean

mixture,

which

creates,

ahigh

combustion

flame

and

high

proportion

of

airin

the

mixture,

which

create

optimal

condition

forNOx

generation.

However,when

run

extremely

lean(below

R

=

0.5),

combustion

temperature

dramaticallydecreases

because

of

strong

thermal

dilution.

Thissignificantly

limits

the

amount

of

NOx

generated.ICEs

can,

in

principle,

run

on

hydrogen

to

produce

mechanicalenergy,

releasing

only

carbon

water

vapour

and

NOx.Converting

an

ICE

to

hydrogen

doesn’t

change

the

principle–

only

a

few

modifications

are

necessary,

although

NOxemission

control

requires

precise

combustion

processmanagement.Other

solutions

can

also

be

used

to

reduce

NOxemissions,

including:These

modifications

are

essential

because:»

Overcoming

reduced

specific

power:

Compared

toan

atmospheric

engine

with

premix

and

spark

ignition,hydrogen

significantly

reduces

(atleast

20to

25%)thespecific

power

of

the

engine

(occupies

a

relatively

largevolume,

decreases

the

amount

of

air

that

can

enter

thecylinder

at

each

cycle).•

Thermal

dilution

with

Exhaust

Gas

Recirculation

(EGR)•

Stratified

combustion,

which

consists

in

preciselycontrolling

the

local

mixture

composition

inthe

combustion

chamber

in

order

to

make

thecombustion

happens

at

optimal

richness.•

NOx

emission

can

be

treated

with

the

appropriateafter-treatment

device

(NOx-trap,

SCR),

which

aretailpipe

devices,

similar

to

catalytic

converters.But

since

a

high

compression

ratio

(the

ratio

betweenthe

volume

of

the

cylinder

and

combustion

chamber)of

13

to

14

is

possible

-

energy

efficiency

can

reach

36%.This

improves

upon

conventional

fuel

engines

wherelower

compression

ratios

(upto

10

nowadays)

meanenergy

efficiency

does

not

exceed

30%.CHART

2:e-Fuel

WTW

energy

efficiency

(source:

Concawe

Reporton

Role

of

e-fuels

in

the

European

transport

system)4BurningHydrogenininternalcombustionengines:asmartandaffordableoptionforreducingCO2

emissionsHYDROGEN

COMBUSTION:

WHATIS

INDUSTRY

DOING?In

this

section,

we

will

look

at

real

world

innovations

towardsutilising

hydrogen

combustion.•

Rolls

Royce

believes

that,

while

hydrogen

can

be

useddirectly

as

a

fuel

in

a

gas

turbine,

it

is

likely

to

start

in

theshorter

haul

segments.

Sustainable

aviation

fuel

(SAF)

gasturbines

will

remain

the

most

likely

solution

for

long-rangeflights,

moving

forward.AutomotiveSo

how

is

the

automotive

industry

adapting?

A

few

notablecompanies

have

made

significant

investments

in

hydrogencombustion.

For

example:Shipping

and

naval•

Toyotais

looking

to

burn

hydrogen

in

ICEs,

while

Hondawill

focus

on

EVs

and

FCEVsShipping

has

been

slower

that

aviation

or

automotive

torespond

to

the

green

transition,

but

changes

are

nowhappening.

The

International

Maritime

Organization

has

setan

ambitious

goal

to

reduce

greenhouse

gas

emissions

in

themaritime

sector

by

50%

compared

to

2008

by

the

year

2050.There

are

few

notable

maritime

commitments

to

hydrogencombustion

at

present,

though

Maersk

is

scaling

up

the

useof

e-methanol,

made

from

green

hydrogen

.

However,thereis

a

growing

pool

of

innovation

that

could

yet

transform

theindustry.

For

example:•

Renault

to

reveal

a

concept

car

equipped

with

a

‘hydrogenengine’•

ORECA

Magny-Cours

to

assess

hydrogen

technology,

whiledeveloping

its

own

hydrogen

ICETo

explore

this

in

more

detail,

we

interviewed

GCK

Group,an

innovative

player

in

green

mobility

and

a

true

believer

onthermal

engine

retrofit

–

to

get

in-depth

technical,

economicand

social

interviews

(see

Interview

1).•

A

Global

Maritime

Forum

analysis

found

over

85zero-emission

vessel

pilots

demonstrations

initiated

during2021and

early

2022,of

which

14

were

pure

hydrogencombustion.Hybrid

solutionsPure

hydrogen

may

not

always

be

possible,

but

it

can

still

helpreduce

emissions

through

a

mix

of

diesel

and

hydrogen.•

A

number

of

companies

and

projects

are

working

onhydrogen

combustion,

including

MAN

Energy

Solutions,who

are

developing

a

hydrogen-fired

four-stroke

shipengine.This

is

something

that

is

already

being

used

in

the

navalmarine

sector,(eg

MAHLE

Powertrain

or

MAN

,

…),anotherindustry

where

batteries

are

so

far

impractical

due

to

theirweight.

Can

it

also

be

a

solution

for

terrestrial

mobility?

Tounderstand

how

this

is

possible,

we

interviewed

ARQUUS,Business

area

Defense

of

the

VolvoGroup,

designing

tailoredsolutions

for

military

applications

(see

Interview

2).Companies

are

exploring

innovative

approaches

to

thestorage

problem.

Startup

Amogy

has

developed

a

systemwhich

converts

ammonia

to

hydrogen,

which

can

thenbe

immediately

used

as

fuel,

as

part

of

a

single

process,addressing

the

need

for

challenging

storage

conditionsof

hydrogen.AerospaceInitiatives

are

underway

–

in

the

air

and

on

the

ground

–

totest

hydrogen-fuelled

ICEs

and

the

direct

use

of

hydrogen

asa

fuel

in

a

gas

turbine.

Examples

include:•

Airbus

and

CFM

International

have

launched

a

joint

projectto

ground-

and

flight-test

a

direct

combustion

enginefuelled

by

hydrogen

in

preparation

for

the

entry

intoservice

of

a

zero-emission

aircraft

by

20355BurningHydrogenininternalcombustionengines:asmartandaffordableoptionforreducingCO2

emissionsINTERVIEW

1:

GREEN

CORP

KONNECTION(GCK),AN

INNOVATIVE

PL

AYER

IN

GREEN

MOBILITYGCK,

based

in

Auvergne-Rhône-Alpes

and

made

up

of

8industrial

companies,

has

built

a

360

degree

approachto

the

energy

transition

for

mobility,

combining

multipletechnological

building

blocks,

their

integration

intovehicles,

and

green

energy

supply.Facedwith

the

challenges

of

decarbonization

of

mobility,Europe

has

chosen

to

move

away

from

a

monopoly

of

theinternal

combustion

engine,

and

towards

a

monopoly

ofelectric

mobility

for

light

vehicles

from

2035.Whetherbased

on

fuel

cell

or

battery

technologies,

this

monopolywill

create

an

upheaval

(technologically,

socially,economically

and

geopolitically)

of

the

entire

automotiveand

vehicle

construction

sector.

The

GCK

group

believesthat

this

trend

will

be

difficult

to

transpose

to

all

heavymobility

or

intensive

professional

use,

due

to

the

reducedversatility

of

battery

or

fuel

cell

electric

vehicles.

This

iswhy

GCK

has

chosen

a

technology-agnostic

approachto

low-carbon

mobility

by

developing

batteries,

electricmotors,

hydrogen

combustion

engines

and

fuel

cellsIn

order

to

respond

with

the

best

technology

adaptedto

each

use

case,

GCK

has

implemented

numeroustechnological

development

projects

over

the

last

fewmonths:

a

range

of

innovative

battery

packs,

a

range

ofhigh

power

density

electric

motors,

a

range

of

hydrogencombustion

engines,

and

a

high

power

fuel

cell

system.GCK

has

become

a

keyplayer

in

the

field

of

vehicles

andthe

integration

of

these

technological

building

blocksthrough

its

heavy

vehicle

retrofit

activity.

The

groupworks

with

numerous

companies

and

local

authoritiesto

convert

fleets

of

combustion

engine

vehicles

(LCVs,coaches,

boats,

refuse

collection

vehicles,

snowgroomers,

etc.)

into

electric,

battery

and

hydrogenvehicles.

To

develop

its

vehicles,

the

group

relies

onits

motorsport

laboratory

and

its

test

centre

at

theCharade

circuit,

where

GCK

has

a

technology

parkproject

dedicated

to

training

and

R&D

on

all

carbon-freemobility

technologies.More

generally,

with

this

strategy

defined

by

Europe,the

vehicle

construction

and

after-sales

industries(maintenance)

will

be

strongly

impacted

by

significant

lossof

jobs

and

skills

around

the

combustion

engine.

It

willalso

be

faced

with

supply

issues

for

components,

mineralsor

materials,

controlled

by

geopolitical

powers

outsideEurope,

and

in

competition

with

other

application

sectors(energy,

industry,

construction,

etc.).Finally,

with

its

Energy

Division,

GCK

provides

mobilegreen

energy

supply

and

refueling

solutions

for

electricand

hydrogen

vehicles.6BurningHydrogenininternalcombustionengines:asmartandaffordableoptionforreducingCO2

emissionsWhile

the

PACand

battery

technologies

are

undeniablyclean

and

virtuous

for

a

large

number

of

uses,

they

are

notthe

only

ones

capable

of

addressing

the

challenges

of

thecarbon

footprint

of

transport

and

mobility,

particularlyheavy

transport.•

It’s

total

cost

of

ownership

(TCO),mainly

due

to

itslow

production

cost,

is

lower

than

battery

or

fuel

cellelectric

vehicles.With

rapid

deployment,

HICE

would

support

the

energytransition

of

the

automotive,

while

preparing

for

thearrival

of

fuel

cell

solutions,

whose

industrial

maturity,while

showing

strong

momentum,

is

not

yet

equivalent

tothat

of

combustion

engines

or,

to

a

lesser

extent,

that

ofthe

battery

sector

for

light

vehicles.The

hydrogen

combustion

engine

solution,

representsa

solution

that

is

as

virtuous

(if

not

better

in

certaincases)

over

a

complete

life

cycle

as

fuel

cell

solutions,while

benefitting

from

the

transition

of

know-how,employment

and

industrial

tools

in

the

sector.Beyond

these

industrial

or

ecological

considerations,the

HICE

solution

will

also

make

it

possible

to

respondto

uses

that

neither

the

fuel

cell

nor

the

battery

cantechnically

or

economically

address

(construction

andmining

equipment,

aeronautics,

etc.).

It

will

provide

realenvironmental

benefit

without

increasing

the

pressureon

a

keyresources

(e.g.copper),

which

should

be

reservedfor

more

important

uses.Indeed,

a

hydrogen

combustion

engine

(HICE)

maintainsthe

same

industrial

model

as

the

diesel

or

petrol

engineand,

with

a

few

adaptations,

most

of

the

components

ofthese

engines

will

be

kept.This

HICE

technology

also

has

a

triple

interest

for

theecological

transition:•

Its

low

CO2impact

during

manufacture•

In

use,

it

is

low

CO2(depending

on

how

the

hydrogen

isproduced)

and

the

almost

total

absence

of

emissions

ofNOx

and

particulate

pollutantsIn

June

2023,

GCK

introduced

one

of

the

world’s

first

GTracing

cars

powered

by

a

hydrogen

combustion

engine

atthe

24Hours

of

Le

Mans.7BurningHydrogenininternalcombustionengines:asmartandaffordableoptionforreducingCO2

emissionsINTERVIEW2:

ARQUUS

COMPANY,LEADER

INDEFENCE

GROUND

MOBILITY

SOLUTIONSThe

French

army’s

defence

energy

strategy

is

based

onthree

parts:

Consume

safely,

consume

less,

consumebetter.In

order

to

respond

to

this

in

the

context

ofexternal

operations,

possible

areas

of

progress

involve:In

order

to

meet

the

needs

of

mobility

of

the

vehicles,

thecompactness

of

the

engines

and

the

potential

use

of

poorquality

fuels,

these

vehicles

will

not

be

able

to

complywith

the

regulations

governing

pollutant

emissions.Even

if

exemptions

to

the

regulations

exist

for

militaryequipment,

these

machines

will

have

to

be

more

virtuouswith

regard

to

pollutant

emissions

when

they

return

tometropolitan

France.•

Increasing

energy

resilience

of

bases

and

systems•

Increasing

agility

of

maneuvering

forces

throughreducing

the

logistical

footprint

of

bases

and

systems•

Controlling

fuel

logistics•

Reducing

dependence

on

fossil

fuels•

Reducing

the

emissions

of

vehicles

on

their

return

tothe

mainlandDual

fuel

solutions,

i.e.

simultaneous

injection

of

dieseland

hydrogen,

can

significantly

reduce

CO2emissions(by

up

to

70%)while

still

being

able

to

operate

on

100%single

fuel

when

returning

to

theatres

of

operation.•

Controlling

operating

costsLand

equipmentThe

use

of

LOHC

(Liquid

Organic

Hydrogen

Carrier)

tosafely

transport

this

hydrogen

becomes

a

relevant

vectorto

transport

this

liquid

in

tanks

capable

of

carrying

eitherconventional

fuel

or

LOHC.For

deployed

equipment

in

the

theatre

of

operations,

thepriorities

concern

the

reduction

of

fuel

logistics

as

well

asthe

autonomy

of

the

vehicles.The

extraction

of

hydrogen

from

the

LOHC

is

donethrough

an

energy

efficient

loop

based

on

a

catalyst

thatrecovers

the

exhaust

gases

from

the

internal

combustionengine

to

trigger

the

process.If

for

the

same

mass,

excluding

the

container,

hydrogen

ismore

efficient

than

hydrocarbons

(factor

#3),

its

volumeand

mass

are

multiplied

by

5

when

integrating

thecontainer

(gaseous

at

700

bar)

or

the

storage

technology(LOHC).

While

maintaining

the

same

autonomy,

its

use

forinternal

combustion

engines

is

not

feasible

for

militaryuse

because

of

its

impact

on

the

architecture

of

thevehicles

and

on

the

fuel

supply

logistics

chain.

Moreover,an

internal

combustion

engine

capable

of

running

oneither

100%

diesel

or

100%

hydrogen

does

not

exist.From

conventional

internal

combustion

engines,

thetransformation

of

these