Hydrogen Production by Water Electrolysis - Messe …€¦ · · 2013-10-02tz-t 01 October 2013...

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01 October 2013 Jürgen Mergel

IEK-3: Electrochemical Process Engineering

Hydrogen Production by Water Electrolysis:

Current Status and Future Trends

IEK-3: Electrochemical Process Engineering 2

Outline

Introduction

Water electrolysis technologies

Alkaline water electrolysis

PEM electrolysis

Requirements for electrolysis by coupling with renewable

energies

Challenges for further development

Summary


Functional principle of water electrolysis

Cathode -

½ O2H+H2

PEM-Elektrolysis20 – 100 °C

H2O 2H+

+ ½ O2 + 2e- Anode

2H+

+ 2e- H2 Cathode

H2O H2 + ½ O2 Total reaction

+ Anode

AnodeIr

CathodePt

Membrane

Cathode -

½ O2O2-H2

High-Temperature-Elektrolysis700 – 1000 °C

O2- ½ O2 + 2e- Anode

H2O + 2e- H2 + O2- Cathode

H2O H2 + ½ O2 Total reaction

+ Anode

AnodeCathode

O2– Ion conductor

Source: Proton OnSite Source: ELT Source: Ceramatec


Water electrolysis - State of the art

Specification Alkaline electrolysis PEM electrolysis

Cell temperature 60 – 80 °C 50 – 80 °C

Pressure ≤ 32 bar < 30 bar

Current density 0.2 – 0.4 A/cm² 0.6 – 2.0 A/cm²

Cell voltage 1.8 – 2.4 V 1.8 – 2.2 V

Cell voltage efficiency* 52 – 69 % 57 – 69 %

Spec. energy consumption stack 4.2 – 5.9 kWh/Nm³ 4.2 – 5.6 kWh/Nm³

Spec. energy consumption system 4.5 – 7.0 kWh/Nm³ 4.5 – 7.5 kWh/Nm³

Load range 20 – 130 % 5 – 300 %

Cell area ≤ 4 m² ≤ 300 cm²

H2 production rate per stack/system ≤ 760 Nm³/h up to 10 Nm³/h / 30 Nm³/h

Lifetime stack < 90,000 h < 60,000 h

Lifetime system incl. maintenance 20 – 30 a 10 – 20 a

Source: NOW-Studie ‚Stand und Entwicklungspotenzial der Wasserelektrolyse zur Herstellung von Wasserstoff aus regenerativen Energien‘, 2011

*relating to LHV: 1.23 V


Water electrolysis - Overview of leading manufacturers of alkaline electrolyzers

Manufacturer Series/operating

pressure

H2 rate

Nm³ h-1

Energy

consumption

kWh Nm-³H2

Load range

%

Hydrogenics HYSTAT /

10 – 25 bar

10 - 75

max.18/stack 5.2 - 5.4 (system)

40 - 100

5 - 120 (optional)

ENERTRAG HyTec

Take over by McPhy

Energy (1 Oct 2013)

NDE-15, NDE-30 / atm.

HDE-05-100/200

10 – 60 bar

185 – 450

100 – 200

4.48 (system)

< 4.75 (system)

20 – 100

25 - 130

Teledyne Energy

Systems

TITAN HM / 10 bar

TITAN EC / 10 bar

2.8 – 12

28 - 56 no details no details

Wasserelektrolyse

Hydrotechnik

EV 01 – EV 150

atmospheric 1 - 250 no details 15 - 100


Water electrolysis - Overview of leading manufacturers of PEM electrolyzers

Manufacturer Series/operating

pressure

H2 rate

Nm³ h-1

Energy

consumption

kWh Nm-³H2

Load range

%

Proton OnSite

HOGEN S / 14 bar

HOGEN H / 15−30 bar

HOGEN C / 30 bar

0.25 - 1.0

2 - 6

10 - 30

6.7

6.8 - 7.3

5.8 - 6.2

0 - 100

0 - 100

0 - 100

Giner Electroch.

Systems

High pressure / 85 bar

30 kW / 25 bar

3.7

5.6

5.4

5.4 no details

CET H2 E5 – E40 / 14 bar 5 - 240 5 no details

H-TEC Systems EL30 / 30 bar 0.3 - 40 5.0 - 5.5 0 - 100

Hydrogenics HyLYZER / 25 bar

GEN3 (1 MW) / 30 bar

1 - 2

250

4.9 (stack) 6.7 (system)

no details

0 – 100

0 - 150

ITM Power HPac, HCore, HBox,

HFuel 15 bar 0.6 - 35 4.8 - 5.0 (system) no details

Siemens 100 kW (300 kW peak)

50 bar ~ 20 - 50 no details 0 - 300


Typical current-voltage characteristics and operating

ranges for alkaline and PEM electrolysis

Source: Mergel, J.; Carmo, M.; Fritz, D.L.: Status on Technologies for Hydrogen Production by Water Electrolysis, Transition to Renewable Energy Systems,

Eds.: D. Stolten, V. Scherer, Wiley-VCH, Weinheim (2013), 423 - 450


PEM water electrolysis

Advantages:

Higher power densities

Higher efficiency

Good partial load toleration

Simpler system structure

Compact stack design allows high pressure

operation

Challenges:

Cost reduction by reduction or substitution of

noble metals and cost-intensive components

Increasing the long-term stability

Scale-up stack and peripherals

Source:

Proton OnSite Source: IHT

Comparison of alkaline and PEM water electrolysis

Alkaline water electrolysis

Advantages:

Well-established technology

No noble metal catalysts

High long-term stability

Units up to 750 Nm³/h (3.5 MW)

Relatively low investment costs

Challenges:

Increasing the current densities

Expanding the part-load capability

System size and complexity

Reduction of gas purification requirements


Requirements for electrolysis by coupling with

renewable energy

2050:

179 GW

40 GW

110 TWh


Requirements for electrolysis by coupling with

renewable energy

MW power range (~ 100 – 200 MW / 50 – 130 t/day)

Pressure operation for cavern storage

High dynamics of the stack and system

Stand-by operation

Frequent starting and stopping

Increased partial load and overload capability


0 2 4 6 8 10

1,2

1,4

1,6

1,8

2,0

2,2

2,4

2,6

2,8

3,0

3,2

Toll of overload on efficiency for a single electrolyzer

Current density / Acm-²

Mean c

ell

voltage / V

200 %

300 %

100 %

(nominal load)

61.5 %

76.9 %

51.3 %

43.9 %

68.3 %

55.9 %

47.3 %

87.8 %

Effic

iency / L

HV

41.0 %

PEM electrolysis, 80 °C

Alkaline

electrolysis

Advanced PEM electrolysis*

* Giner, Inc., 2013 DOE Hydrogen Program Annual Merit Review Meeting


Production costs for hydrogen*

Electricity price is the most important variable for the plant

gate cost of hydrogen

followed by electricity use (kWh/kg)

and then by production purchased capital cost

Investment cost and installed electrolysis capacity

PEM Electrolysis

Stack and BoPs dominate

system costs

CCM, current collectors and

bipolar plates dominate stack

costs

Anode: Ir, Ru, Pt, mixed

oxides (2 – 6 mg/cm²)

Cathode: Pt (1 – 2 mg/cm²)

Separator plates and current

collectors (Ti, coated with

PGM)

*Source: Current (2009) State-of-the-Art Hydrogen Production

Cost Estimate using Water Electrolysis, NREL, 2009

Source: Proton Onsite



PEM Electrolysis


system costs



costs






PGM)


PEM Electrolysis


system costs



costs






PGM)

State-of-the-art (2013)

0,0 0,5 1,0 1,5 2,0

1,2

1,3

1,4

1,5

1,6

1,7

1,8

1,9

2,0

2,1

2,2

Ce

ll V

olta

ge

/ V

Current Density / A cm-2

80 °C

50 °C


2.440



PEM Electrolysis

Approaches for cost reduction

Reduction and substitution of

noble metals

Anode: Ir, Ru ~ 0,6 mg/cm²

Cathode: Pt ~ 0,2 mg/cm²

Low-cost, long-life separator

plates and current collectors

Scale-up single cell > 1.000 cm²

Reduction of BOP capital cost

nominal load

nominal load

Current density /

Cell

voltage /



PEM Electrolysis


Reduction and substitution of

noble metals

Anode: Ir, Ru ~ 0,6 mg/cm²

Cathode: Pt ~ 0,2 mg/cm²

Low-cost, long-life separator

plates and current collectors

Scale-up single cell > 1.000 cm²

Reduction of BOP capital cost


Source: D. Fritz, M. Carmo, J. Mergel, D. Stolten, Modeling of a PEM electrolyzer for component design,

manuscript in preparation.

Challenges for further development - Overpotential losses

CCMs - Catalyst layers - Membrane

Endplates Separator plates Current collectors


Challenges for further development - Alkaline water electrolysis

New electrocatalysts to decrease overpotentials and increase efficiency

New diaphragms to increase partial load and minimize ohmic losses

Enable alkaline water electrolysis for overload operation

Anode: Ni/Co/Fe

Cathode: Ni/C-Pt

Advanced (FZJ, 1979 – 2002)

conventional



New electrocatalysts to decrease overpotentials and

increase efficiency

New diaphragms to increase partial load and minimize

ohmic losses

Enable alkaline water electrolysis for overload operation

1 MW Prototype (Lurgi/FZJ, 1994)

100 cells, 1.6 m diameter

200 Nm³ H2/h and 100 Nm³ O2/h

Nominal current 5000 A, nominal current density 3 kA/m²

spec. energy consumption (stack) 3.9 – 4.1 kWh/Nm³ H2 Source: Fortschrittliche Wasserelektrolyse, Lurgi,

Wasserstoff als Energieträger, Wasserstoff-

Statusseminar, Würzburg, 24. Oktober 1995

Current density

Sp

ec. en

erg

y c

on

su

mp

tio

n

Spec. energy consumption



Specification Type NDE-30 Type HDE-05-200

Cell temperature 80 °C < 80 °C

Pressure atmospheric 10 … 60 bar

Spec. energy consumption < 4.48 kWh/Nm³ < 4,75 kWh/Nm³

Part-load range 20 % 25 %

H2 production rate max. 450 Nm³/h max. 200 Nm³/h

2 MW NDE stacks

Source: ENERTRAG HyTec

take over by on October 1, 2013


Challenges for further development - PEM water electrolysis


Reduction and substitution of noble metals

Anode: Ir, Ru ~ 0.6 mg/cm²

Cathode: Pt ~ 0.2 mg/cm²

Low-cost, long-life separator plates and current collectors

Scale-up single cell > 1000 cm²

Source: M. Carmo, D. Fritz, J. Mergel, D. Stolten

Int. J. Hydrogen Energy, 2013. 38(12): p. 4901-4934









Source: M. Carmo, D. Fritz, J. Mergel, D. Stolten

Int. J. Hydrogen Energy, 2013. 38(12): p. 4901-4934

80 °C, Nafion112


Challenges for further development - Cell efficiency vs. catalyst loading, Pt loading cathode, 80 °C, Nafion 117

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0

1,4

1,5

1,6

1,7

1,8

1,9

2,0

FZJ CCMs:

Loading cathode:

0.8 mgPt

cm-2

0.2 mgPt

cm-2

Anode:

2.25 mgIrcm

-2

2.25 mgIrcm

-2

Ce

ll vo

ltag

e /

V

Current Density / Acm-2


Challenges for further development - Cell efficiency vs. temperature & membrane thickness

Nafion 117

°



0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,51,4

1,6

1,8

2,0

2,2

30 oC - 0.75 Acm

-2

50 oC - 1.00 Acm

-2

70 oC - 1.28 Acm

-2

80 oC - 1.46 Acm

-2

Ce

ll vo

ltag

e /

V

Current Density / Acm-2

Increasing operating temperature

can improve membrane

conductivity and catalytic activity

Requirements:

Improve catalyst durability

Reduced gas permeation

Nafion 117

Cathode: 0.8 mgPt/cm²

Anode: 2.25 mgIr/cm²



Nafion 117

°



Nafion 115

°


Challenges for further development - Cell efficiency vs. membrane thickness

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0

1,4

1,5

1,6

1,7

1,8

1,9

2,0

Nafion 117

Nafion 115

Nafion 112

Cell

voltage / V

Current density / Acm-2

ambient pressure, 80 °C

Decreasing membrane thickness

can improve voltage efficiency but

decreasing faraday efficiency

Nafion 117 – 1.00 Acm-2

Nafion 115 – 1.20 Acm-2

Nafion 112 – 1.85 Acm-2


Challenges for further development - Cell efficiency vs. membrane thickness & pressure

80 °C

0,0 0,5 1,0 1,5 2,00,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

112

115

117

j (A/cm²)H

2 in

O2 (

%)

1bar

Gas diffusion losses are highly dependent on

membrane thickness, operating pressure and

temperature

Source: Pressurized PEM water electrolysis: Efficiency and gas crossover

M. Schalenbach, M. Carmo, D. Fritz, J. Mergel, D. Stolten, Int. J. Hydrogen Energy (2013), article in press


Challenges for further development - Stack efficiency vs. membrane thickness & pressure

80 °C

At low and moderate operating

pressures stack efficiency are

mostly dependent on iR-losses




Challenges for further development - Stack efficiency vs. membrane thickness & pressure

Simulated anodic hydrogen content

in dependence of current density at

30 bar and balanced and differential

pressure

Simulated stack efficiency loss due to

crossover and ohmic losses at 30 bar

for balanced and differential pressure



Faraday efficiency losses are

lower in differential-pressure

operation

Highly dependent on membrane

thickness, operating pressure and

temperature









Source: First International Workshop on

Endurance and Degradation Issues in PEM

Electrolysis, March 12th, 2013 | Freiburg, Germany Source: Symposium on Water Electrolysis and Hydrogen as Part of the Future

Renewable Energy System, 10-11 May 2012, Copenhagen, Denmark









Source: First International Workshop on

Endurance and Degradation Issues in PEM

Electrolysis, March 12th, 2013 | Freiburg, Germany

Source: Giner Inc.

65 kW / 0.9 m²/cell PEM electrolyzer stack (low-pressure)


Summary

Through the extension of the renewable energies, new challenges emerge with

respect to the storage of large energy quantities.

Hydrogen produced by water electrolysis from renewable energies can solve the

problem of power fluctuation

Only alkaline and PEM electrolysis are commercially available

Investment costs for PEM electrolyzers must be drastically cut

PEM electrolysis development focuses on cost reduction, improving long-term

stability and increasing system size

In addition to more materials research (catalyst and membranes) current

densities and stack size for alkaline electrolysis must be increased and the ability

to handle overloads must be improved


Acknowledgements

Co-workers:

Marcelo Carmo

David Fritz

Maximilian Schalenbach

Daniel Holtz

Stefanie Fischer

Thank you for your attention !

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