1: Hydrogen as Energy Vector · 2008-05-19 · Typical Installation of a Prereformer Feed from HDS Process steam Prereformer Waste heat channel CO 2 (optional) Tubular reformer. 13

1

Summer School, Girona, May 2008

Hydrogen. Advances and ChallengesJens Rostrup-Nielsen

1: Hydrogen as Energy Vector

2

SNG from Naphtha (1966)

Methanation Feed (vol%). Inlet 1st Methanator

195625P, bar

1.236.436.22.04.7

19.4

DakotaSNG est.

1.20Inerts22.60H2O21.235.7CH4

4.110.2CO2

8.82.0CO42.152.1H2

TREMP / PH

SNGfrom

naphtha

3

Hydrogen Production

Gas Station

Car

Refinery

Gasoline 5.2 $/GJH2 5.5 $/GJ

Gasoline 7 $/GJH2 20 $/GJ

Oil 25 $/bNG 3.5 $/MMBTU

Present Hydrogen Consumption

Petroleum refining

Ammonia production

Chemical industry

Rocket fuel

Annual consumption– US : 12 million t/yr

– World: 50 million t/yr

MeOHMisc.

Space

Refinery NH3

4

Manufacture of Hydrogen Today

48% steam reforming of NG

30% refinery by-product

18% gasification of coal

4% electrolysis

IEA 2005

Economy of ScaleH2O/CH4

Air

H2O/CH4O2

Syngas

Air

H2O/CH4O2

Syngas

Log capacityLog capacity

Log costsLog costs TubularReforming

O2-plant

5

CO2 Free Power Production

Syngasgenerator

&shift

Steamgeneration

Flue gas

to stackCO free2

H (N )2 2H ,CO

(N )2 2

2

Naturalgas

CO to sequestration2

Air

COcapture

2

2: Hydrogen by Steam Reforming

6

Particle Migration and Coalescence

H2, 600°C

Ni/MgAl2O4

7

Formation Formation ofof WhiskerWhisker CarbonCarbon in in SituSitu HRTEM HRTEM CHCH44/H/H22 = 1:1, P = 5 m bar, T = 720= 1:1, P = 5 m bar, T = 720°°C)C)

Typical Reformer Conditions for Hydrogen

16901560Xx oF

920850Texit, oC

2525P, bar

1.84.5H2O/C

NewConv.

8

Hydrogen Plant. Simplified Scheme.

◄

H2-plant based on Steam Reforming of Natural Gas

9

Hydrogen Production by Steam Reforming

Natural Gas: 3 USD / MM BTU

Natural Gas: 7 USD / MM BTU

100187

Capital10

Fixed25

Feed + fuel65

Capital10

Fixed25

Feed + fuel152

Hydrogen by Steam Reforming. (NG price: 3 USD/GJ)

13.59.66.75.5H2 costs (USD/GJ)

422111.99.4Investment (USD/GJ/y)

46.74661.173.2LHV efficiency (%)

340Liq.7878H2, pressure bar

SmallLargewith CCS

Large

IEA 2005

10

H2 from SMR is very Efficient

CH4 + 2H2OliqReaction heat (298 K)Methane (LHV)Total

Theoretical min.

Practical value SMR:Energy efficiency:LHV efficiency:

CO2 + 4H2 - Q

12.6 GJ / 1000 Nm3 H294%94%85.7%85.7%

253 kJ / 4 mol H2803 kJ /4 mol H2

1056 kJ / 4 mol H2

11.8 GJ / 1000 Nm3

300 BTU / SCF H2

Steam Reforming ofHigher Hydrocarbons Mechanism

Ni Ni Ni Ni Ni Ni Ni Ni

CHx + OCHxCH2+

CO, H2Cn-2Hz

CnHm Olefins Coke

11

Ethylene Formation in Fuel Processing

Pyrolysis (steam cracking)

CnHm → olefins + H2

Oxidative coupling

2CH4 + O2 = C2H4 + 2H2O

DehydrationC2H5OH = C2H4+ H2O

Pyrolysis (steam cracking)

CnHm → olefins + H2

Oxidative coupling

2CH4 + O2 = C2H4 + 2H2O

DehydrationC2H5OH = C2H4+ H2O

12

Typical Installation of a Prereformer

Feed from HDS

Process steam

Prereformer

Waste heat channel

CO2 (optional)

Tubularreformer

13

Sulfur Poisoning on Nickel

Besenbacher et al.

H2S + NiSurface S- NiSurface + H2

The Dream Reaction

CH4 + ½O2 = CO + 2H2 +38kJ/mol

CH4 + 2O2 = CO2 + 2H2O

CO + H2O = CO2 + H2O

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CatalyticCatalytic PartialPartial OxidationOxidation

210 Nm3/h CO + H2

CnHm ⇒ CO+2H2H2S ⇒ SO2

CH4+H2O CO+3H2CO+H2O CO2+H2

SO2 ⇒ H2S

O2

H2

15

Sulphur Reactions on Reforming Catalysts

Ni + H2S = Ni-S + H2

Ni-S + 1.5 O2 = NiO + SO2

SO2+3H2 = H2S + H2O

Rh + H2S = Rh-S + H2

Rh-S + O2 = Rh + SO2

Ni + H2S = Ni-S + H2

Ni-S + 1.5 O2 = NiO + SO2

SOSO22+3H+3H22 == HH22S + HS + H22OO

Rh + H2S = Rh-S + H2

Rh-S + O2 = Rh + SO2

3: Alternative Fuels

16

Routes for Hydrogen Production

Nuclear energy Fossil energy Renewable energy

BiomassHeat

Mechanicalenergy Heat Photo-

elec-tro-

lysis

Fer-men-tation

Nuclear energy Electricity

Biophoto-lysis

ElectrolysisChemical conversionElectrolysisThermo-lysis

Hydrogen

CO2-free Hydrogen

Wind

Nuclear

Solar

ElElectrolysis

H2

O2

Biomass

H2

WindNuclear

Solar

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Overall Efficiency may be Doubtful

Power 100%

H2 by electrolysis 80%

Liquefaction 70%

Fuel cell 50%

PowerTotal 28%

Stolten, Jülich

Solar Energy

Heat

El

H2

18

H2 from Biomass

Biomass

Gasification

EOH

H2

H2

Sugars

Process Routes for Conversionof Carbohydrates to Fuels

BiomassSugars,glycol,etc.

Fermentation

Reforming

Catalytic processing

14%EOH

93%EOH

Fuel Fuel

(25% EOH)

Science 308(2005) 1422

“CH2”

H2

EOH

19

Coal Conversion

Gasifier Conversion02

Coal

CO2 for seque-stration

H2, synfuels

4: Are we on the right track?

20

Main Issues for H2 - Economy

H2 storage

H2 transportation

CO2 sequestration

Renewable energy (solar)

Cheap, reliable fuel cells

21

Fuel Cell Conversion. Direct or Indirect

Relative Exergy, Ideal conditions, 25°CHeat input by combustion

CH4 el1.0

4H2

1.130.32

Fuels via Synhesis Gas

Natural gasCoalBiomass

Syngas

Science 308(2005) 1421

ICE and CO2

Fuel cell cars

Synfuel

H2

22

Electrons or Hydrogen or ?

Elgrid

Electriccars

FCcars

ICEcars

Wind

Bio

Natural gas

H2

A Future for a Hydrogen Economy?