Advanced Alkaline Electrolysis

Dana Swalla, Ph.D.GE Global Research Center

Niskayuna, NY

This presentation does not contain any proprietary or confidential information

Project #PDP14

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Acknowledgements

Acknowledgment: This material is based upon work supported by the Department of Energy under Award Number DE-FC-0706-ID14789

Disclaimer: This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

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OverviewTimelineStart: 30 September 2006End: 30 December 200870% complete

BudgetTotal Funding: $1,239,479DOE Share: $ 973,783Contractor: $ 265,696

funded by both the DOE Nuclear Hydrogen Initiative and DOE HFCIT programs

Received in 2007: $524,8412008 Funding (to date) : $283,710

Barriers AddressedG. Capital Cost of Electrolysis SystemsI. Grid Electricity Emissions

PartnersGE Global ResearchGE Energy NuclearEntergy NuclearNational Renewable Energy Laboratory

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ObjectivesStudy the feasibility of using alkaline electrolysis technology with current-generation nuclear power for large scale hydrogen production:

Economic Feasibility : Market study of existing industrial H2 usersTechnical Feasibility : Developing pressurized low cost electrolyzerCodes and Safety: Environmental and regulatory impact assessment

Units DOE 2012 TargetCell Efficiency % 69% (1.8V)System Cost $/kg H2 $0.70 ($400/kW)Electricity Cost $/kg H2 $2.00O&M Cost $/kg H2 $0.60

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ApproachTask 1: Define market and requirements

• Industrial users survey• Technical and pricing requirements • Nuclear regulatory and environmental impact issues

Task 2: Design and build pressurized electrolyzer stack• Develop plastic stack technology • Low cost electrode methods

Task 3: Plastics oxidation lifing• Creep resistance• Oxidation

Task 4: Demonstrate electrolyzer performance and capital costsTask 5: System operation testing

• O&M cost assessmentTask 6: Create industrial-scale system conceptual designTask 7: Create 1-kg-per-second demonstration system

conceptual design

100% complete

80% complete

50% complete

10%

50%

50% complete

10% complete

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Industrial Hydrogen Markets

Global consumption: 42 million tons H2 per year

1

10

100

1000

10000

100000

1000000

0 50 100 150 200 250 300 350

Number of Sites (US)

Site

Cap

acity

, kg

H2/d

ay

Ammonia Production

Petroleum RefiningFloat

Glass

FoodHydrogenation

Electronics

Metals

BWR Water Chemistry

GeneratorCooling

1

10

100

1000

10000

100000

1000000

0 50 100 150 200 250 300 350

Number of Sites (US)

Site

Cap

acity

, kg

H2/d

ay

Ammonia Production

Petroleum RefiningFloat

Glass

FoodHydrogenation

Electronics

Metals

BWR Water Chemistry

GeneratorCooling

Large scale operations: 90% of consumption

Mid-scale Industrial

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An Existing, Growing Market• 4 million tons H2 / year for mid-range industrial

• Per-site consumption on order of 100-1000 kg per day

• 15% yearly growth

• Currently served by delivered gas or liquid

• Required pressure varies – but much lower than automotive storage scenario

• Costs vary significantly : $4-$15 per kg

Distributed Electrolysis Can Fill Growth Demand, If Cost-Competitive

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existing fleet - US 1995-2005

0.01.02.03.04.05.06.07.08.09.0

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Nuclear 1.72Coal 2.21

Gas 7.51Oil 8.09

Cen

ts /k

Wh

(200

5)

Source: NEI, 2006

Electricity Production Costs

Lowest cost electricity available from existing nuclearElectricity market demands set actual price

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Electrolysis Cost of Hydrogen

Capital Cost, $/kW$4,000 $800 $400

1.0 $4.79 $1.51 $1.102.0 $5.29 $2.01 $1.603.0 $5.79 $2.51 $2.104.0 $6.30 $3.01 $2.605.0 $6.80 $3.52 $3.116.0 $7.30 $4.02 $3.617.0 $7.80 $4.52 $4.118.0 $8.30 $5.02 $4.61

Cost of Electricity,

¢/kWh

Basis is the NRELH2A model, modified from the 1500 kgpdcase.

• Industrial point-of-use case: No dispensing or distribution costs.

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Stack Module CostsElectrolyzer Stack Module Cost

0

5000

10000

15000

20000

25000

prototype 5kgphpressurized

entitlement 5kgphpressurized

projected 20kgphpressurized

Dol

lars

per

kgp

h ca

paci

ty

0

50

100

150

200

250

300

350

400

450

500

Dol

lars

per

kW

@ 5

0 kW

h/kg

assembly labor

electrode cost

plastic cost

vessel cost

Size Power* Module Cost

5 kgph 250 kW $45,800

20 kgph 1 MW $150,000

* Assumes 50 kWh/kg H2

Cost scenarios based on actual cost of demonstration stack, projected assembly and labor costs.

Balance of system costs are additional, and depend on system size.

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OHH

OO

e-

H+H+

H+H+

HHHH

e-e-

e-

e-

e-e-

e-

electrolyte

O2 H2H2

OHH

current

2 H2O + ELECTRICITY → O2 + 2 H2

electrode electrode

oxygen hydrogen

waterO

HHO

HH

OO

e-

H+H+

H+H+

HHHH

e-e-

e-

e-

e-e-

e-

electrolyte

O2 H2H2

OHH

OHH

current

2 H2O + ELECTRICITY → O2 + 2 H2

electrode electrode

oxygen hydrogen

water

+ _

Diaphragm Bipolar conductor

Porous Cathode Porous Anode

Multicell Bipolar Stack

catholyte passage

anolyte passageanode

separation diaphragm

cathode other side

Bipolar type half-cells

Cathode (-):2H2O + 2e- 2OH- + H2

Anode (+):2OH- H2O + 2e- + ½ O2

Electrolysis Basics

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GE Plastic Stack Technology

Completed stack assembly

• Injection-molded sections• Complex features all

molded in the plastic – not machined in the metal

• Sheet metal/mesh electrode

• Single plastic mold for demonstration: 3D / multiple molds in full production

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Electrode Assembly

Plastic weld

Diaphragm cartridge

Diaphragm cartridge

x9

Stack end assembly (machined from molded blanks

Stack end assembly (machined from molded blanks

9 cell stack core

Plastic Stack Construction

10-cell Stack module

(shell, bolts, current straps not shown)

15 bar pressure stack completed and ready for testing

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Plastic Joining Method and Testing• Research on

various plastic grades

• Accelerated testing for high pressure oxidant exposure

• Plastics retain high yield strength

• Joint typically as strong as plastic base material

Wedge Breaking Test

Joint Finite Element

Post Testing

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GE Electrode Technology

1 10 100

base metals

GE electro –deposited

GE spray

precious metals

Cell

Ove

rpot

entia

l

Relative Cost per Unit Area

TargetZone

dimensionallystabilized anode (DSA)

2004-2005 Project : Wire-arc sprayed high surface electrodes

Higher Efficency

Lower Cost

Today : Electrodeposition

1 10 100

base metals

GE electro –deposited

GE spray

precious metals

Cell

Ove

rpot

entia

l

Relative Cost per Unit Area

TargetZone

dimensionallystabilized anode (DSA)

2004-2005 Project : Wire-arc sprayed high surface electrodes

Higher Efficency

Lower Cost

Today : Electrodeposition

• Achieved target performance with hot spray technique in 2005.

• Demonstrating electrodeposition for additional cost and performance advantage:

- Thinner bipolar plate- Eliminates warping- Coats 3D electrode surface

GE electrode technology applies a high effective surface area, nickel-based coating to the base metal bipolar plate for high performance at low cost.

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Cell Performance

Alkaline Electrolyzer Cell Tests

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

2.20

2.40

2.60

2.80

3.00

Current Density, mA/cm2

Cel

l vol

atge

, vol

ts

Coated Mesh Electrode

Plate, Pre-Deposition

Plate, Post Deposition

• Wire-arc sprayed electrode tested in 2005-2006• Electrodeposition successful at small scale: Performance improvement: - 0.2V or

better• Coating uniformity and plating conditions verified using full-size single cell rig• Electrodeposition of full size, 10-cell demonstration stack completed

Single Cell

anod

eca

thod

e

Solid Bipolar

Plate

Current collector

Inlets

Performance test from bench scale cell Uniform, stable coating verified on full-size single cell

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Tensile and bending specimens in O2 tested to 40-62 equivalent weeks at a design pressure of 15 bar and at 80C

Accelerated material testing

• Polysulfone materials, Udel® and Radel®, retain ductility and yield strength

• Noryl® EN265 and modified Noryl® EN265 maintain yield strength, but limited or no ductility

Udel® and Radel® most likely candidates for long term electrolyzer operation

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Additional Work: “1 kgph” System

Study operability & maintenance characteristics

Capabilities:• 1 kg H2 / hr production rate• Currently being upgraded to

15 bar pressure capability• Automated controls• P, T, massflow, purity

measurements

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Cooper Nuclear Station – Nebraska• Unipolar design generates 7.5 SCFM or 3,942,000 SCF per year.• 90% - 97% availability• No special regulatory or licensing issues because hydrogen is generated on demand – no storage. • Onsite production roughly ½ the cost of delivered hydrogen.

Industrial scale system designIn collaboration with Entergy, the background, performance, and operational history of electrolyzers at Cooper Nuclear Station and Pilgrim Stations used to benchmark system costs and regulatory issues.

Pilgrim Nuclear Station – MA• The electrolytic hydrogen water chemistry (EHWC) system capable of producing 50 SCFM H2 and 25 SCFM O2.

• Availability less than 50%…. Attributed to poor facility design and ability to easily maintain.

• System no longer in operation.

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Hypothetical Electrolyzer Facility w/ tie in to Air Products Hydrogen Pipeline

Reactor Building

Existing H2 Pipeline

1 kgps Commercial Scale SystemWaterford 3 Generating Station, located in Hahnville, LA is an example of a possible 1 kgps electrolysis plant site

• Energy usage: 50 kWh per kg of hydrogen to produce 1 kgps = 180 MW of electric power.

• Water consumed: 9.2 liters of water/kg of hydrogen produced = 7000 gallons/hr.

• Assume (4) - 200 cell modules powered from the same rectifier in electrical series.• Each module draws 1500 amps, cell voltage is 1.6 V = 480 kW/module or 1920 kW per power block.

• Each rectifier produces 1500 A at 1280 VDC.

• 90 power blocks required to produce 1 kgps of hydrogen.

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2008: System testing at ambient and 15 bar pressureO&M cost assessmentMaterial lifing studiesConceptual design of reference plantsComplete regulatory assessment

Future Work