d09.06.04.presentation

High Temperature Electrolysis Experimental Activities At The Idaho National Laboratory

Carl StootsJames O’BrienJ. Stephen HerringIdaho National Laboratory

Joseph HartvigsenCeramatec Inc., Salt Lake City, UT

Thomas L. CableUniversity of Toledo, Cleveland, OH, USA

High Temperature Electrolysis Limiting FactorsKarlsruhe, Germany, June 9 – 10, 2009

Stoots, HTE Limiting Factors, Karlsruhe, 2009

Overview

• INL HTE is funded by the US DOE Nuclear Hydrogen Initiative (NHI)• The goal of the NHI is to demonstrate the economic, commercial-scale

production of hydrogen using nuclear energy. • INL is lead lab under the NHI for studying HTE• Historically we have concentrated on SOEC designs from Ceramatec Inc.• With increasing interest in H2 production, we have tested more designs from

various vendors• My talk – overview of experimental activities at INL with some Lessons Learned

Typical Ceramatec SOEC Stack

Rolls Royce Fuel Cell Systems

NASA BSC Stack


Electrolysis Experimental Activities

Multi-cell (Stack) Testing

Button cell testing

different cell designs & vendorscell material performancelong term performance -- degradation

BOP issues• thermal management / heat recuperation• H2 recyclemulti-stack manifolding / interconnectsassess technology readiness

Bench Scale

Integrated Laboratory Scale (15kW)

ILS Facility (15kW)

Bench scale test stands


INL Bench Scale Electrolysis Test Apparatus (Button Cell)

Bench Scale CapabilitiesINL can simultaneously test:• two button cells• two stacks• special stand for single cell testing

T

P H

D I Water

TPH

T

TsTsT

TTT

I

V

To Roof Vent

T

T

V

Ts

T

T

Nitrogen

Hydrogen

Air

CoolingWater

SV


INL Bench Scale Electrolysis Test Stands


NASA Bi-Supported Cell (BSC)

Construction:

• Structurally symmetric• Electrolyte supported by both

electrodes• Electrodes made by freeze casting and

infiltration (nitrate solution)• YSZ scaffolding• Graded porosity• Ni cathode• LSF anode

• YSZ electrolyte• High power-to-weight ratio (1 kW/kg?)


NASA BSC Sweeps

Cell area = 2.25 cm2

T = 850 CH2,inlet = 50 sccmN2,inlet = 350 sccmTdp,inlet = 50 C, 62 CyH2O,inlet = 0.35

0

0.1

0.2

0.3

0.4

0.50.8

0.9

1

1.1

1.2

1.3

1.4

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Initial Sweep 1Initial Sweep 2Sweep at 20 hoursSweep at 40 hoursSweep at 80 hours

Vol

tage

(V)

Current Density (A/cm2)

ASR

(Ωcm

2 )

Inlet Dew Point T = 50 C

Inlet Dew Point T = 62 CT

furnace = 850 C

H2,inlet

= 50 sccm

N2,inlet

= 350 sccm

Inlet Dew Point T = 50 C


NASA BSC Long Duration Test

Cell area = 2.25 cm2

T = 850 CH2,inlet = 50 sccmN2,inlet = 350 sccmTdp,inlet = 50 C, 62 CyH2O,inlet = 0.35

2

2.1

2.2

2.3

2.4

2.5

2.6

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0 100 200 300 400

Cur

rent

(A) A

SR (Ω

cm2)

Elapsed Time (hours)

Tfurnace

= 850 C

Vref

= 1.2 V

Inlet Dew Point = 62 CH

2 = 50 sccm

N2 = 350 sccm

Swee

pSw

eep

Add

ed in

sula

tion

to v

alve

s Swee

p

Lost

pow

er

Tem

pora

ry sh

ut d

own

Current (A)

ASR

Experimental disruptions affect degradation• Erratic steam flow due to condensation• Power losses• Thermal transients


Typical Steam Electrolysis Stack Test Ceramatec 10 cell, 20cm x 20cm

0

5

10

15

770

780

790

800

810

820

830

0 20 40 60 80 100

Stack Voltage (V)

ASR (Ωcm2)Stack T #1 (C)

Stack T #2 (C)

Stack T #3 (C)

Stac

k O

pera

ting

Vol

tage

(V)

ASR

(Ωcm

2 )

Stack Internal Tem

perature (C)

Stack Current (A)

Per-Cell ASR

StackVoltageH2 production measured by:

• Change in dew points• Cell current

Measurement of internal stacktemperatures

6

7

8

9

10

11

12

13

14

0

1000

2000

3000

4000

5000

6000

7000

8000

0 20 40 60 80 100

H2 Production (dew points)

H2 Production (current)

Stac

k O

pera

ting

Vol

tage

(V) H

2 Production Rate (sccm

)

Stack Current (A)

StackVoltage

H2

Production


Typical Steam Electrolysis Stack Test Ceramatec 10 cell, 10cm x 10cm

0

5

10

15

50 100 150 200 250 300

Shunt Current (A)Vint #1Vint #2Vint #3Vint #4Power Supply Voltage (V)Stack Operating Voltage (V)ASR

Elapsed Time (hrs)

Humidifier performance erratic -- humidifier float valve failed and had to be replaced.


INL 15 kW Integrated Laboratory Scale Test

Designed to study BOP issues:• thermal management• heat recuperation• H2 recycle• multi-stack gas manifolding• multi-stack electrical interconnects• technology readiness



Full operation – September 2008• 3 parallel semi-independent loops• H2 recycle• heat recuperation



Safety: One electrical disconnect point for entire experiment


INL ILS Data Acquisition and Control

• Software written in-house using LabView• Lesson learned – high bias voltage problems• 2 National Instruments SCXI signal measurement / conditioning systems

• Isolate high bias voltage measurements from others• 233 I/O channels


INL H2 Recycle Components

• Double-diaphragm H2 recycle pump• Feed-back controlled via computer• User-selectable product recycle split

• H2 recycle storage tank• Condensation in pressurized H2 product is important


INL ILS Modules

• Modules provided by Ceramatec Inc.• Each cell is 10cm x 10cm (8cm x 8cm active area)• Module comprised of 4 60 cell stacks• 3 modules (total of 720 cells)• Stacks are electrically interconnected every 5th cell


Final Installation Of Cells

Module measurements include voltages, currents, temperatures

240 cells plus manifolds are heavy!


INL ILS Heat Recuperation Design• Internally manifolded, plate-fin design• 2 heat exchangers per module

• One for steam hydrogen• One for air sweep

• Heat recuperation reduced total electric heater power requirements by half

Example CFD calculation for INL heat recuperation concept


Three Module ILS Results

• 18 kW peak electrolysis power• 5.7 Nm3/hr peak H2 production rate• Ran for 1080 hours• Condensation in H2 MFCs caused problems for first ~500 hours -> degradation• Proper design and operation of BOP important for cell performance.• Electrolyser cell performance degradation remains problem.

0

1

2

3

4

5

6

0

5

10

15

20

200 400 600 800 1000

H2 Production (Nm3/hr)

Mod 1 ASR

Mod 2 ASR

Mod 3 ASR

H2 P

rodu

ctio

n R

ate

(Nm

3 /hr)

Per-Cell A

SR (Ω

cm2)

Elapsed Time (hrs)

Peak 5.7 Nm3/hr

0

0.5

1

1.5

2

2.5

3

3.5

4

0

5

10

15

20

16 17 18

ASR

(Ωcm

2 )

H2 Production R

ate (Nm

3/hr)

Electrolysis Pow

er (kW)

Elapsed Time (hrs)

Electrolysis Power (Peak = 18kW)

H2 Production Rate (Peak = 5.7 Nm3/hr)

Module 1 Per-Cell ASR




Steam Electrolysis Experimental Status

• Studying electrolysis degradation mechanisms through bench scale testing

– Dr. O’Brien will speak more about this

• Continuing to characterize performance of cells from various vendors


Coelectrolysis Experimental Activities


• Smaller/lighter (more mobile) molecules of H2 -H2 O pair could favor steam electrolysis– Our Area Specific Resistance (ASR) measurements support this:

• ASRcoelectrolysis ~ ASRH2O• ASRdry CO2 > ASRH2O

• Seems that:– H2 O consumed in electrochemical reaction– CO2 consumed in RSR

• Dry CO2 electrolysis is not desirable– High ASR– Possibility of further reduction of CO to C

OHCOHCO 222 +⎯→⎯+

22,

2 22 OHOH heatyelectricit +⎯⎯⎯⎯ →⎯

2,

2 22 OCOCO heatyelectricit +⎯⎯⎯⎯ →⎯Steam electrolysisCO2 electrolysis????Reverse shift reaction

22,

22 OCOHCOOH heatyelectricit ++⎯⎯⎯⎯ →⎯+Coelectrolysis


Steam vs. Coelectrolysis ASRs

Same stack800 C operating temperature

• Dry CO2 ASR significantly higher than steam ASR• Stack performance same for steam electrolysis or coelectrolysis• Explanation (as stated earlier):

• H2 O consumed in electrochemical reaction• CO2 consumed in RSR

6

7

8

9

10

11

12

13

14

0 5 10 15 20 25

Stac

k O

pera

ting

Vol

tage

(V)

Stack Current (A)

H2O Electrolysis

CO2 Electrolysis

ASRCO2

~ 3.84 Ωcm2

ASRH2O

~ 1.36 Ωcm2

H2O/CO

2 Coelectrolysis

ASRH2O/CO2

~ 1.38 Ωcm2


Typical Coelectrolysis Stack Results

• At zero current (no electrolysis)• CO2 , H2 consumed• CO produced

• Yield of syngas increased linearly with current• oxygen is removed from gas mixture

• Good agreement with INL-developed coelectrolysis model

0

5

10

15

20

0 2 4 6 8 10 12

Mol

e %

(Dry

Bas

is)

Electrolysis Current (A)

Inlet CO2

Inlet CO

H2

CO

CO2Inlet H

2

Reverse shift reaction

Model Results

Experimental Results


0

20

40

60

80

100Te

st 1

, Sta

ck In

let

Test

1, S

tack

Out

let

Test

1, M

etha

natio

n O

utle

t Te

st 2

, Sta

ck In

let

Test

2, S

tack

Out

let

Test

2, M

etha

natio

n O

utle

t Te

st 3

, Sta

ck In

let

Test

3, S

tack

Out

let

Test

3, M

etha

natio

n O

utle

t Te

st 4

, Sta

ck In

let

Test

4, S

tack

Out

let

Test

4, M

etha

natio

n O

utle

t Te

st 5

, Sta

ck In

let

Test

5, S

tack

Out

let

Test

5, M

etha

natio

n O

utle

t

CH4

CO

CO2

N2

H2

Coelectrolysis With Subsequent Methanation

Ceramatec extended coelectrolysis with downstream methanation reactor

• 18mm x 1.5m tube• Commercial steam reforming

catalyst (R-67R, Haldor Topsoe)• Outer sleeve to reduce axial

temperature gradient• Reactor T = 300 C• 40% - 50% CH4 (by volume)

produced


Coelectrolysis Experimental Status• Designing and constructing an integrated demonstration

– Syngas via electrolysis

– Methane via methanation of syngas

– Liquid synfuel

• Methanol

• Fischer-Tropsch liquids

d09.06.04.presentation

Documents

factors karlsruhe

c inlet dew point

sccm inlet dew point

c cell area

overview inl hte

single cell testing

cell bsc construction

c yh2o