Development of SOFCs for Development of SOFCs for Liquid FuelsLiquid Fuels

May 5, 2009N. Fernandes, D. Schmidt,

N. Bessette

OutlineOutline

1. Introduction to Acumentrics2. Acumentrics’ SOFC Technology3. Development of SOFC for Military Use4. Reliability

– Mechanical strength- Shock and Vibration– Thermal Shock– Liquid Fuels

5. Future Work

Acumentrics Corporation• ~ 80 Employees• Manufacturing since 1994• Based in Westwood, Mass.• ~40,000 sq. ft facility• Profitable for the past 30 months• Critical disciplines in-house

Electrical EngineeringMechanical EngineeringChemical EngineeringThermal ModelingCeramics ProcessingManufacturingSales & MarketingAutomationFinance

Industrial-UPS®Commercial

Rugged-UPS®Military

Acumentrics Battery based UPS

Uninterruptible Power Supplies for Harsh

Environments

Features:• Sealed electronics• Able to withstand vibration• Unity power factor input• Wide input 80VAC - 265VAC• Isolated 120 / 240VAC output• Hot swap battery case• Parallelable to 20 kWatts

Why Solid Oxide Fuel Cells?Why Solid Oxide Fuel Cells?

PEM– Polymer MEA, H+ charge carrier– Low temperature

• Light weight assemblyBut

• Acutely susceptible to poisons (CO and Sulfur), thus heavy fuel processor• Expensive Pt catalyst because of slow kinetics

SOFC– Ceramic MEA, O2- charge carrier– High temperature

• Heavy ceramics and metalsBut

• Inexpensive catalysts (e.g. Ni) due to fast kinetics• CO is a FUEL, not a poison• Bottoming cycle is possible, high efficiency

High temperature favors reforming kinetics and thermodynamics, SYNERGY

Rugged Tubular SOFC Rugged Tubular SOFC

Tubular, anode supported, SOFC

Anode

Electrolyte

Cathode 4e-

2e- 2e-

O2N2

COH2

CHx CO2

H2 O

Exit GlacierExit Glacier

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Operation for another summer at Exit Glacier Visitor’s Center

Shutdown at end of season

Fuel: Propane

Products: hot water for radiator heating and electrical power

Cuyahoga State ParkCuyahoga State Park

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Fuel: Natural gas

Products: electrical power

Location: Outside, grid tied

SECA Phase I GeneratorSECA Phase I Generator

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•Total run time 10,500hr

•Major ESTOP event at 3200hrs

•18 Thermal cycles

•Shipped twice (part of SECA Phase I testing at NETL)

•2004 cell technology

Micro CHPMicro CHP

3 have been built to date

Has started CE certification

Plan to undergo testing with the MTS consortium in the next month

1kWel AC out, 20kWth eff(all)=85%,

SOFC for Military ApplicationsSOFC for Military ApplicationsHigh Performance

– High power density, small and light– Silent– Rapid start-up– Efficient, water neutral

Reliable– Mechanical, shock and vibration– Thermal, shock and thermal cycling– Electrical, load cycling– Chemical, poison (sulfur) and fouling (carbon) resistance

SOFC for Military ApplicationsSOFC for Military Applications

The fuel cell stack and BOP assembled onto the frame of a transit case

Electrical Load CyclingElectrical Load Cycling

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Cell voltage recovery after operation at >100% Fuel Utilization

1000x Load Cycling 1000x Load Cycling

Mechanical TestingMechanical Testing

MTS 5 28x22mm bundle with tube sheet

NTS vibration table surface

Single axis accelerometerTriple axis accelerometerSingle axis control accelerometer

Z

X

Y

22mmAnd15mm cells

MIL-STD-810F 2 Wheel trailer 30 min vibration test

Electrical TestingElectrical Testing-- Thermal cyclingThermal cycling

Electrical TestingElectrical Testing-- Thermal cyclingThermal cycling

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1. Unload cell and go to OCP- 5min2. Go to Purge gas-Lower Temp to 300C3. Back to 800C-start H2, wait 10min4. Load 30 minutes and record data5. Loop

Loaded Cell performance graphs show aLoss rate of about 1%/100TC~4000hr run time/1500hrs at power

Thermal Cycles on StacksThermal Cycles on Stacks

Hours Run Time Notes0 7/29/08 10:21 Start / Cycle 1

0.59 7/29/08 10:57 light reactor0.99 7/29/2008 11:21 CPOX3.17 7/29/08 13:32 Pre-Reactor inlet sa4.48 7/29/08 14:50 OCV5.71 7/29/08 16:04 1505.85 7/29/2008 16:12 2265.95 7/29/08 16:18 shutdown, stack vol

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Micro CHP Thermal CyclingMicro CHP Thermal Cycling

Schedule:•About an hour down to ~200C•Less than 30 min back to power•Run•Redo

20 thermal cycles

Purgeless cycles

Excellent recovery

Thermal GradientsThermal Gradients

1/3 cell sitting OUTSIDE furnace6 Thermal Cycles459 load hours

Fuel FlexibilityFuel Flexibility

High energy density fuels

JP-8 MIL-T-83133– Aromatics 15-20%– Olefins 1-2%– Saturates 78-83%– Sulfur 10-1000ppm

Synthetic JP-8 – Saturates 100%– Sulfur < 0.1ppm

LPG– Sulfur up to 180 ppm

Sulfur PoisoningSulfur Poisoning

Sulfur present in large quantities in military fuels (possibly up to 1wt%)

Common fuel cell catalysts susceptible to sulfur poisoning (need <10ppm)

Solutions:

Liquid/Vapor Phase removal

Gas phase(H2 S) removal

REFORMER

increase Sulfurtolerance

JP8

Sulfur Testing on Single CellsSulfur Testing on Single Cells

JP8 ReformingJP8 ReformingReforming Modes

– Steam reforming (H2 O, CHx )• High efficiencies, requires significant water (high S/C), heat

transfer difficulties, larger reactors, upstream liquid phase desulfurization

– Partial oxidation (O2 ,CHx )• Less efficient, but small reactors and fast dynamics, down stream

gas phase desulfurization

– Autothermal reforming (O2 , H2 O, CHx )• Best (and worst) of both worlds?

Reforming Techniques– Catalytic, Plasma, Thermal

Water NeutralityWater Neutrality

Water at the military front is expensive!– e.g. 1 gal JP8 requires ~2 gal water at

S/C=2Solution: Fuel cells produce water

Recycle water from anode exhaust

REFORMERAir

Fuel

Catalytic Reforming at AcumentricsCatalytic Reforming at Acumentrics

Breadboard testing of reformersSteam Reforming

– >1000hr testing on S-8 (zero sulfur) S/C=4– 300W stack test

Partial Oxidation – JP-8 (~280ppmS) CPOX reformer at steady state– 24 hr test on 1kW stack

ATR– ATR reformer– 1000hr testing on JP8 (~10 ppmS) on a 1kW stack– 2 days of transient testing, load following and cycling

Steam Reforming of Synthetic JP8Steam Reforming of Synthetic JP8

48 gal of Synthetic JP8 reformed over 1550 hours. Total cell testing time on reformate was 1330 hours.

Longest continuous cell testing (300W bundle) were 624 and 427 hr periods; stops due water and diesel pump failures.

Longest continuous reformer operation was 1171 hours.

Testing done mostly at S/C=4, also down to 3.5

Total reformer testing to date approximately 2500hrs as scheduled.

Water pre heater/boil er

S-8 fuel

Reformer

Steam super heater

S-8 inlet

Reformate outlet

1 kW JP1 kW JP--8 CPOX8 CPOXJP8, 280 ppmW S, O/C=1.03

Shutdown due to low V

JPJP--8 CPOX 24 hr test8 CPOX 24 hr test

Disintegrated anode, carbon, Ni and YSZ free particles

Carbon deposition throughout hot manifolds and cells Carbon deposition throughout hot manifolds and cells (O/C~1). Temperature boundary for carbon deposition (O/C~1). Temperature boundary for carbon deposition is ~800is ~800ooC (C (thermodynamicthermodynamic))

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CH4 Methane CH1.86 JP-8 CH2.12 S-8 CH2.67 Propane

CPOX CaveatCPOX Caveat

CARBON

1000 hr ATR test on JP1000 hr ATR test on JP--88

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Transient TestingTransient Testing

Going ForwardGoing Forward

Integration of SOFC stack with ATR reformer– SOFC controls ATR, enabling transient

testing (fast start-up, load following, thermal cycling)

– Incremental integration to full water neutrality

Continued testing of reformers

Thanks toThanks to

Reginald Tyler of EEREDon Hoffman, John Kuseian, John

Heinzel of ONRMTS/Consortium membersAcumentrics Team