Fuel Cell & Hybrid Fuel Cell Gas Turbine System Design

© National Fuel Cell Research Center, 2011 1/66

Fuel Cell & Hybrid Fuel Cell Gas Turbine

System Design, Dynamics & Control

Jack Brouwer, Ph.D.

Associate Director

April 18, 2011


Outline

• Introduction

• System Design and Steady State Performance

• Dynamic Performance & Understanding

• Control Systems Development

• Summary


Introduction

• Energy Systems are critical to:

• Economies – all sectors

• Quality of Life

• Freedom of Mobility

• A few important aspects of Energy Systems

• Thermodynamics

• Heat Transfer

• Fluid Dynamics

• Chemistry

• Dynamics

• Controls

• Systems Integration

• Environmental Impacts

• Consider All

• Make simplifying assumptions

• Rigorously analyze the

important physics/chemistry/etc.

in an integrated fashion


Fuel

Introduction: Fuel Cell System

Fuel Cell Power Plant or Engine

• Fuel cell stack

• Fuel processing – Reformer and gas clean-up

• Electric power conversion – inverter and power conditioner

• Balance of plant – heat exchangers, controls, valves, fans, …

Fuel

Processor

H2-rich

gasFC Stack

and Power

Block

DC

PowerPower

Control &

Conversion

AC

Power

Useful Heat

Water

Clean

Exhaust



Major System Components

Fuel processing• Source for the hydrogen

– Water - need energy for hydrolysis

– Hydrocarbons - consume some of the fuel energy

• Technology for conversion– Emissions?

– Reliability

– Efficiency

– Cost

Power conversion and electronics• Direct current (DC) to alternating current (AC)

– Needed for today’s end-use technologies

• Technology– Efficiency

– Reliability

– Cost



Major System Components (cont’d)

Controls

• Reliability

• Safety

– Hydrogen

• Integration

Balance of plant

• Valves

• Regulators

• Seals

• Plumbing

• Sensors/displays

• Heat exchangers

• Humidifiers / Condensers

AC

DC

Air In

Air Filter

GT

Compressor

GT Turbine

Start

Combustor

Exhaust

Recuperator

By-Pass

Valve

Blow-Off

Valve

Start Air

Heater

Solid Oxide

Fuel Cell

(SOFC)

Fuel Inlet (Natural Gas)Fuel

Heater

Fuel

Desulfurizer

Fuel Reforming

Reactor

Fuel By-Pass

Valve

Inert Gas

Generator

Anode Exhaust

Gas Flow

Fuel

Flow

Air

Cooler

Direct-Drive

Generator

Rectifier

DC Current

Out

Reformed

Fuel Flow

Air In

Not Mundane:

Understanding

Design &

Performance

are Essential



Fuel Processor - System design variations

Low temperature fuel cell system

• Temperature of FC heat

not compatible with

fuel processor

• Susceptible to

poisoning

High Temperature fuel cell system

• Temperature of FC heat

is compatible with

fuel processor

• More inherent

fuel flexibility


Fuel Cell Gas Turbine Hybrid System

Hybrid Fuel Cell/Gas Turbine Systems

C

C

CAir

Fuel

C TT Generator

C = Compressor; T = Turbine

Combustion 60%

70%

70+%

HYBRID FC/GT

Introduction: Hybrid System Concept

1 MW

2011

Gas Turbine System


Introduction

Needs for Fuel Cell Systems Advancement

• Understanding and use of thermodynamics & heat

transfer for the design & analysis of integrated systems

• Understanding of integrated fuel cell and hybrid fuel cell gas turbine system dynamics• Fuel cell systems

• Gas turbine systems

• Solar and wind power systems

• Batteries, ultracapacitors, inverters, other energy storage or

conversion devices as integrated into systems

• Dynamic models of fuel cell physics, chemistry,

electrochemistry

• Development and evaluation of control systems and

strategies for fuel cells

• Macro energy systems integration (e.g., utility grid)


Outline

• Introduction




• Summary


Air

Motor

SOFC

Blower

Oxid-

izer

Oxid-

izer

Refor-

mer

Heat

Exch.

Fuel

+ H2O

Exit

Heat

Exch.Steam

Prep.

System Design

Integrated Stand-Alone systems

• SOFC minimum component realization

• Motor-blower, steam preparation, reformer reactor, oxidizer and

heat exchangers

Mueller, F., Jabbari, F., Brouwer, J., Journal of

Power Sources, Vol. 187, Iss. 2, pp. 452-460, 2009


System Design

Integrated Stand-Alone systems

• PEMFC minimum system realization

• Pump, water recovery

(enthalpy wheel), stack,

ATO, humidifier

stack cooling,

DI water circuit

• Desulfurizer,

humidifier,

CPO, several

HTS reactors,

LTS, PROX,

several heat

exchangers

Min, K.D., Kang, S., Mueller, F.,

Auckland, J. and Brouwer, J. J. Fuel Cell

Sci. Technol., Vol. 6, 041015, 2009

Fuel

DI Water

Air (O2/C)=0.6

DI Water

Air InAnode Inlet

Condensed Water


Hybrid System Configurations

AirGenerator/

Motor

Compressor

Turbine

Heat

Exch SOFCOxid-

izer

Oxid-

izer

Fuel

Blower

Comb

Fuel

Fuel Cell Module

Bleed

Exhaust

SOFC

Air

Fuel

+ H2O

Generator/

Motor

Compressor

Turbine

Heat

Exch.Exit

Oxid-

izer

Oxid-

izer

Refor

mer

Refor

mer

Fuel

Air

Fuel

+ H2O

Gen

Comp

ressor

Turbine

Fuel

Heat

Fuel

Heat

Oxid

izer

Heat

Exch

Heat

Exch

FC

Ref

Heat

Exch

Heat

Exch

Gen

NG

SOFC

Turbine Turbine

NG

Compressor

C1 C2

HX

Comb

Ref

Exhaust


Integrated Gasification Fuel Cell Plant

IGFC Concept Introduction

Coal

Prep.

Coal

Gasification

Syngas

Clean-upSOFC

Gas

TurbineSteam

Turbine

CO2 Separation

& Recycle

A catalytic hydro-gasifier IGFC system that takes advantage of the

potential benefits of CH4-rich syngas fuel can achieve more than 60%

efficiency while enabling carbon dioxide separation for sequestration

Li, et al., Journal of Power Sources,

Vol. 195, Iss. 17, pp. 5707-5718, 2010.


Model Development

• Most system development and analyses are based upon

bulk (0-dimensional) models

• Several important operating constraints cannot be

assessed without some geometric resolution of the SOFC

• Peak temperature, temperature gradients

• Fuel & oxidant utilization

• We desire to resolve some features of modern SOFC

operation

• need computational simplicity/efficiency sufficient to incorporate

the model into detailed integrated gasification systems analysis

• Explicitly evaluate activation, ohmic, and diffusion losses as well

as kinetics of hydrocarbon reactions

• Predict performance features such as the internal temperature,

current/power density and flow composition profiles, fuel and

oxidant utilization, for evaluation of fuel cell operating constraints


Planar SOFC Model Geometry

Quasi-2D co/counter flow planar SOFC model

Li, M., Powers, J.D., and Brouwer, J., Journal of Fuel Cell

Science and Technology, Vol. 7, pp. 041017-1-12, 2010


Key Simplifications & Assumptions

• Steady state model

• Resolve gradients in primary flow direction

• 4 separate temperatures resolved in each node

• Positive electrode-electrolyte-negative electrode (PEN) structure

• interconnect

• fuel flow

• air flow

• H2 electrochemical oxidation only (CO oxidized through

water-gas shift reaction)

• Water-gas shift reaction is always in equilibrium

• Methane reformation is controlled by local chemical kinetics

• External heat loss is by radiation heat transfer to vessel only

• Large Peclet number, effect of axial heat conduction in gas

phases is negligible Li, M., Powers, J.D., and Brouwer, J., Journal of Fuel Cell



Numerical Scheme

Li, M., Powers, J.D., and Brouwer, J., Journal of Fuel Cell


PEN

PSR PSR PSR

PSR PSR PSR


1-D Model Integration into Systems Analysis

Catalytic hydro-gasifier IGFC system

HP SOFC & Heat

Exchange System

(1-D, 0.8V, 73% f)

Li, et al., Journal of Power Sources,

Vol. 195, Iss. 17, pp. 5707-5718, 2010.


1-D counter-flow SOFC model in integrated IGFC analysis

• Peak temperatures move to SOFC interior

• Inlet & outlet temperatures no longer represent peak T

• Outlet fuel/air temperatures are decreased – disabling

downstream heat use

• Air flow required for ∆Tmax=200°C is 4X that of 0-D

model

Challenges Identified: 0-D vs. 1-D

fuel out

(650 + 200) °Cair out

(650 + 200) °C

fuel in

650 °C

air in

650 °C

fuel out

(650 + 40) °Cair out

(650 + 70) °C

fuel in

650 °Cair in

650 °C


IGFC Performance Comparison

Item 0-D Model 1-D Single Stage

Counter-flow SOFC

Coal energy input 1,397 GJ/h (HHV) 1,397 GJ/h (HHV)

SOFC operation pressure 10 atm 10 atm

Gross power output

SOFC electrical power 247.8 MW 247.3 MW

Cathode exhaust expander 63.4 MW 178.6 MW ↑

Steam turbine 2.6 MW 1.9 MW

Syngas reactor/expander topping cycle 9.3 MW 7.6 MW

Total gross power generated 323.3 MW 435.6 MW ↑

Auxiliary power consumption (incomplete list)

ASU 2,186 kW 2,186 kW

SOFC air compressor/blower 66,906 kW 242,499 kW ↑↑↑

Recycled H2 compressor 8,235 kW 8,283 kW

Total internal power consumption

and losses84.7 MW 260.5 MW ↑↑↑

Net electric power 238.6 MW 175.1 MW ↓↓↓

Overall thermal efficiency 61.5% (HHV) 45.1% (HHV) ↓↓↓

Li, M., Rao, A.D., Brouwer, J., and Samuelsen, Journal of

Power Sources, Vol.195, Iss. 17, pp. 5707-5718, 2010.


Strategy for Mitigating High T Challenge

Cascade SOFC stacks

Overall

Uf = 0.727

Ua = 0.455

Air in

650°C

Fuel in

650°C

Fuel out

671°C

Uf = 0.70

Ua = 0.15

Air addition

330°C

Air

713°C

Fuel in

650°C

Fuel out

689°C

Uf = 0.73

Ua = 0.16

Air addition

330°C

Air

732°C

Fuel in

650°C

Fuel out

704°C

Uf = 0.73

Ua=0.17

Air addition

330°C

Air

742°C

Fuel in

650°C

Fuel out

719°C

Uf = 0.74

Ua = 0.17

Air out

753°C




IGFC Performance Comparison

Item 0-D Model 1-D Cascading

Counter-flow SOFCs

Coal energy input 1,397 GJ/h (HHV) 1,397 GJ/h (HHV)

SOFC operation pressure 10 atm 10 atm

Gross power output

SOFC electrical power 247.8 MW 247.8 MW

Cathode exhaust expander 63.4 MW 72.1 MW ↑

Steam turbine 2.6 MW 2.7 MW

Syngas reactor/expander topping cycle 9.3 MW 7.6 MW

Total gross power generated 323.3 MW 330.4 MW ↑

Auxiliary power consumption (incomplete list)

ASU 2,186 kW 2,186 kW

SOFC air compressor/blower 66,906 kW 84,748 kW ↑

Recycled H2 compressor 8,235 kW 9,792 kW ↑

Total internal power consumption

and losses

84.7 MW 104.3 MW ↑

Net electric power 238.6 MW 226.1 MW ↓

Overall thermal efficiency 61.5% (HHV) 58.2% (HHV) ↓




Extend to Quasi-3D Cross-flow Planar SOFC

Quasi-3D cross-flow planar SOFC model – sample results

plots of cross flow planar SOFC PEN temperature and current density distributions

operated on syngas containing ~17 vol.% CH4 Uf = 85%, Ua = 14.7%


Outline

• Introduction




• Summary


Dynamic Simulation Approach

Dynamic Energy Systems Simulation Framework

• MATLAB/Simulink® environment selected• User friendly, widely available/used, ideal for controls

development and testing

• Main assumptions:• quasi-steady state chemistry and electrochemistry (e.g.,

characterized by Nernst potential and losses)

• Simplified geometry (but including some geometric resolution)

• Focus on dynamic solution of the essential FC and other component features such as:• Nernst potential

• Electrochemical losses

• Species concentrations and Mass conservation

• Energy conservation

• Momentum conservation

• Heat Transfer

• Chemical ReactionGemmen, R, Liese, E., Rivera, J., Jabbari, F, and

Brouwer, J., ASME Paper Number 2000-GT-554, 2000.


Dynamic Simulation Approach

out

NinNin

outN

out

OHOHinOHin

outOH

out

COCOinCOin

outCO

out

HHinHin

outH

outRinout

out

outout

N

dt

VCdXN

X

N

dt

VCdRXN

X

N

dt

VCdRXN

X

N

dt

VCdRXN

X

dt

VCdNNN

RT

PC

)()(

)(

)()(

)(

)()(

)(

)()(

)(

)(

22

2

222

2

222

2

222

2

R+N-N=dt

dCV iii

i

outletinlet

)ii/-(1nF

TR-=L L

uC ln

F-AP-AP=dt

vdV soutletoutletinletinlet

)(

]][[

][]][[ln

,22

2/1

,2

2/1

22

aCOOH

cCOOHu

yy

Pyyy

nF

TRE=E

)i(i/Fn

TR=L o

uA ln

PP=P ac,

ACR LLLE=Vcell

Species Conservation Sample Mass Conservation Equations

Momentum Conservation

Nernst Equation

Electrochemical Losses

Cell Voltage

iR=L cellR

Roberts, R., Mason, J., Jabbari, F., Brouwer, J., Samuelsen, S., Liese,

E. and Gemmen, R., ASME Paper Number 2003-GT-38774, 2003.


Example Dynamic Simulation Modules

• Cell Solid

• Interconnect Plates

Planar and Tubular SOFC Discretization – 10 Nodes

• Anode Gas

• Cathode Gas

10 NODES

REFORMED

FUEL

CATHODE GAS

CELL SOLID INTERCONNECT

ANODE GAS

CELL TUBE

AIR SUPPLY PIPE

CATHODE GAS

CROSS SECTION

REFORMED

FUEL

PRE-

HEATED

AIR



• PLANAR NODAL SOFC HEAT TRANSFER

RESISTANCES

BI-POLAR PLATE

NODE n NODE n+1

x

RRAD

RCONV

RCONV

RCONV

RCOND

RCONDRCOND RCOND

RCOND

RRAD

RCOND

RCONV

RCONV

RCONV

ANODE

IN

ANODE

OUT

CATHODE

OUT

CATHODE

IN

RCONVRCONV

RRAD RRAD

CELL

BI-POLAR PLATE

RCONDRCOND RCOND



• REFORMER – Siemens Power Type

• 5 node model

• Concentric cans

• Heat from exhaust gas heat exchange

NODES

NATURAL

GAS

EXHAUST

STEAM /

DEPLETED FUEL

REFORMATE

FC EXHAUST

Adiabatic Mixing Volume

Catalyst Bed



GAS TURBINE

• Based on generic compressor/expander performance maps

• Dynamic mass conservation through the plenum volume

• Shaft speed and angular momentum are solved by sum of the

torques method on the turbine shaft

Air In

Compressed Air OutCompressed Air OutPlenum

Volume

Power = Torque*RPM

Hot Compressed Air In

Alternator

lossloadCT PPPPJ

1

t

)( outin mmV

RT

dt

dP


Sample Module Evaluation and Verification

• Model Integration and Verification: Single MCFC Test

Stand



• MCFC Comparisons of Agglomerate, Simplified

Models & Data



• MCFC Comparisons of Agglomerate, Simplified

Models & Data


Quasi 3-D Dynamic FC Model Verification

35/

Fuel Inlet

Air Inlet

Active Cell (550cm^2)

5x5 Grid

Cross-flow Configuration

0

0.05

0.1

0.15

0.2

0.25

0 0.05 0.1 0.15 0.2 0.25

Fuel Flow Direction

Air F

low

Dire

ctio

n

980

990

1000

1010

1020

1030


Sample System Simulation Evaluation

220 kW HYBRID SYSTEM:

• SCE, Siemens Power Corp. - SOFC with IRES micro-turbine

• Over 2950 hours of operation; 53% net AC electrical efficiency



• Siemens Power Corporation (with SCE)Air

Natural

Gas

Generator/

Motor

CompressorTurbine 1

SOFC

Exit

Anode

Cathode

Heat

Exch.

Turbine 2

Comb Natural

Gas

Comb Natural

Gas

Air

Natural

Gas

Generator/

Motor

CompressorTurbine 1

SOFC

Exit

Anode

Cathode

Heat

Exch.

Heat

Exch.

Heat

Exch.

Turbine 2

CombCombCombComb Natural

Gas

CombCombCombComb Natural

Gas



• Model Integration and Verification: Sample ResultsSOFC Power Experimental and Model Comparison

for the 220 kW SOFC/GT Hybrid

140

145

150

155

160

165

170

175

180

0 20000 40000 60000 80000 100000 120000 140000 160000

Time (sec)

SO

FC

Po

we

r (k

W)

an

d F

ue

l F

low

SL

PM

*(0

.30

)

0

5

10

15

20

25

30

35

Va

lve P

erc

en

t O

pe

n

Model SOFC Power

Experimenta SOFC Power

SOFC Fuel Flow

Recuperator Bypass Valve

SOFC Bypass Valve

Experimental SOFC Power



• Model Integration and Verification: Sample ResultsGas Turbine Power Experimental and Model Comparison

for the 220 kW SOFC/GT Hybrid

15

17

19

21

23

25

27

29

31

0 20000 40000 60000 80000 100000 120000 140000 160000

Time (sec)

GT

Po

we

r (k

W)

0

5

10

15

20

25

30

35

Pe

rce

nt

Op

en

Model GT Power

Experimental GT Power

Recuperator Bypass Valve

SOFC Bypass Valve



• 220 kW Hybrid – Diurnal Variation – Power (solid = data)

120

135

150

165

180

160

170

180

190

200

210

220

230

240

Time (hours)

SO

FC

Po

wer

(kW

)

15

20

25

30

35

Valv

e P

erc

en

t O

pen

;

Gas T

urb

ine P

ow

er

(kW

)

SOFC Power SOFC Power Model

Gas Turbine Power Gas Turbine Power Model



• 220 kW Hybrid – Diurnal Variations – VI (solid = data)

1600

1700

1800

1900

2000

160

170

180

190

200

210

220

230

240

Time (hours)

Avera

ge C

urr

en

t D

en

sit

y (

A/m

2)

0.65

0.675

0.7

0.725

0.75

Avera

ge C

ell V

olt

ag

e (

V)

Current Density Current Density Model

Voltage Voltage Model



• 220 kW Hybrid – Start-up – Power (solid = data)

120

135

150

165

180

120

130

140

150

160

Time (hours)

SO

FC

Po

wer

(kW

)

15

20

25

30

35

Valv

e P

erc

en

t O

pen

;

Gas T

urb

ine P

ow

er

(kW

)

SOFC Power SOFC Power Model

Gas Turbine Power Gas Turbine Power Model



• 220 kW Hybrid – Start-up – VI (solid = data)

1600

1700

1800

1900

2000

120

130

140

150

160

Time (hours)

Ave

rag

e C

urr

en

t D

en

sit

y (

A/m

2)

0.65

0.675

0.7

0.725

0.75

Ave

rag

e C

ell

Vo

lta

ge

(V

)

Current Density Current Density Model

Voltage Voltage Model


Outline

• Introduction




• Summary


Control Approach Overview

Dynamic

ModelPower

&

DisturbanceTransient

Response

Operating

Requirements

Control

Concept

Input

Understand control challenges physically

Control & system solutions

Evaluate trade-offs and performance

Goals: Understand dynamic performance characteristics, develop and test control

concepts, and enhance the transient load following and disturbance rejection

capability of SOFC systems

Identify/capture control challenges

Tune designExtensively using models

to develop/evaluate controls


System Transients and Control Concepts

Air

Motor

SOFC

Blower

Oxid-

izer

Oxid-

izer

Refor-

mer

Heat

Exch.

Fuel

+ H2O

Exit

Heat

Exch.Steam

Prep.

Manipulated Variables

Goals

Control Challenges

• Current

• Fuel flow

• Air flow

• Bypass valve

• Load following

• Handle disturbances

& ambient variations

• Fuel depletion

• Fuel cell thermal management

• System power control

• Combustor temperature control

System Design

• Air preheating

• Reformer temperature

• Fuel steam to carbon

SOFC Example


Example: Fuel Flow and Current

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 20 40 60 80Current (A)

Ce

ll V

olt

ag

e (

V)

0

5

10

15

20

25

30

35

40

45

Ce

ll P

ow

er

(W)

V(U=85%) V(U=80%) V(U=75%) V(U=70%)P(U=85%) P(U=80%) P(U=75%) P(U=70%)

(K-I)P

rPfc

yPgt

ui+

Sat.Sat.

rP

yPfc

+ePfc

FFi

rP

bifi

+

+

fNfc

(K-I)tc

etc bNfcrtc

ytc

rP

uNfc

+

+

+

FFNfc

Sat.Sat.

1195

1205

1215

1225

1235

1245

0.001 0.01 0.1 1 10 100

Time (s)

Co

mb

us

tor

Te

mp

era

ture

(K

)

N=0.2s-P=inst.

N=2s-P=inst.N=10s-P=inst.

N=10s-P=30s

Fuel

Depletion


Example: FC Thermal Management

in,AnodeTXN

mol

kJ8.241HOHO

2

1H 298222

out,AnodeTXN

HEATHEAT

in,CathodeTXNout,CathodeTXN

MEA

ANODE

CATHODE

mol

kJ0.165HCOH4OH2CH 2982224

mol

kJ15.41HCOHOHCO 298222

Chemical

Reactions

Electro-Chemical

Reaction

ELECTRIC ELECTRIC

WORKWORK

x

Thermal

EMF

Current

Vo

ltag

e

Nernst

Voltage

Operating

Voltage

GH

ST

Operating Point

Power Generated

Heat Generated

fBY

(K-I)T

eT bBYrT

yT

rP

uBY

+

+

+

FFby

Sat.Sat.

genoutoutoutinininV Q)T(hN)T(hNdt

dTC

Gen

NG

SOFC

Turbine Turbine

NG

Compressor

C1 C2

HX

Comb

Ref

Exhaust


Example: System Integration

uNtc

yTIN

uBY1

yP

rP ui

uBY2

uNfc

F(s)

N(s)

yTstack

F(s)~ Power Controller

N(s)~ Fuel Cell Fuel Flow Controller

B(s)~ Fuel Cell Temperature Controller

C(s)~ Cathode Inlet Temperature Controller

T(s)~ Turbine Inlet Temperature Controller

B(s)

C(s)

yTstack

ytit

T(s)

ytc

SO

FC

Syste

m

Centralized control approaches (e.g., H-Infinity) work well

Decentralized control loops are possible due to variety of system response times

Feed forward to get actuators close to desired operating point

Feedback to reject undesired transients and external disturbances

Gen

NG

SOFC

Turbine Turbine

NG

Compressor

C1 C2

HX

Comb

Ref

Exhaust


Application to Fuel Cell System Controls

• MCFC Hybrid (after FuelCell Energy DFC/T® design)Air

Fuel

+ H2O

Generator/

Motor

Compressor

Turbine

MCFC Oxid-

izer

Fuel

Heater

Heat

Exch.

Heat

Exch.Exit

Anode

Cathode

Roberts, R.A., Brouwer, J., Liese, E., Gemmen, R.S., Journal of Engr.

for Gas Turbines and Power, Vol.128, Iss. 2, pp. 294-301, 2006.



• Open Loop MCFC Temperature Transient - Cathode

Inlet Temperature Rises (848 871 K) during load shed


Air

Fuel

+ H2O

Generator/

Motor

Compressor

Turbine

MCFC Oxid-

izer

Fuel

Heater

Heat

Exch.

Heat

Exch.Exit

Anode

Cathode


• MCFC Hybrid (after FuelCell Energy DFC/T® design)

Maintain a safe

operating temperature

for the catalytic

oxidizer

• Control Goals

• Maintain proper

temperatures

throughout the hybrid

system

• Maintain operation of

the gas turbine

• Operate the MCFC

efficiently and safely

Control compressor

mass flow by

manipulating generator

power with MCFC

temperature feedback

Fuel flow rate into the

MCFC is controlled to

maintain a safe

oxidizer temperature &

MCFC voltage

Roberts, R.A., Brouwer, J., Liese, E., Gemmen, R.S., Journal of Engr.




System Power: Control Approaches #1 & #2, Load Shed

700

750

800

850

900

950

1000

1050

0 10 20 30 40 50 60 70 80 90 100Time (s)

Fu

el C

ell P

ow

er

(kW

) ;

To

tal

Po

wer

(kW

)

100

105

110

115

120

125

130

135

140

145

150

Ga

s T

urb

ine

Po

we

r (k

W)

NFCRC Total NETL Total NCFRC FC

NETL FC NFCRC GT NETL GT

App. #1 – TOTAL

App. #2 – FC

App. #2 – TOTAL

App. #1 – GT

App. #1 – FC

App. #2 – GT

Roberts, R.A., Brouwer, J., Liese, E., Gemmen, R.S., J. Engr.




1090

1100

1110

1120

1130

1140

1150

0 10 20 30 40 50Time (s)

Cata

lyti

c O

xid

izer

Tem

pe

ratu

re (

K)

835

837

839

841

843

845

847

849

Cath

od

e In

let

Te

mp

(K

)

NFCRC Catalytic Ox. Temp NETL Catalytic Ox. Temp

NFCRC Cathode Inlet Temp NETL Cathode Inlet Temp

Temperatures: Control Approaches #1 and #2, Load Shed

App. #1 – Catalytic Ox Temp

App. #1 – Cathode Inlet Temp App. #2 – Catalytic Ox Temp

App. #2 – Cathode Inlet Temp

Roberts, R.A., Brouwer, J., Liese, E., Gemmen, R.S., J. Engr.




• Closed Loop MCFC Temperature Transient - Cathode

Inlet Temperature Drops during load shed


Example: Sudden Decrease of Power

Hybrid SOFC/GT System

• Manipulate:

• Recirc. blower power

• Fuel flow

• Air preheat bypass valve

• SOFC air bypass valve

• Control:

• System power

• Peak SOFC temperature

• SOFC temperature gradient

• Oxidizer temperature

• Perturbation:

• Sudden decrease from 100%

to 50% full powerMcLarty, D.F., Samuelsen, S., and Brouwer, J.

ASME Paper FC2010-33328, June, 2010


Example: Sudden Decrease of Power

Hybrid SOFC/GT System

• Met sudden decrease

in power demand

• Kept SOFC peak

temperature < 1073 K

during transient

• Kept SOFC temperature

gradient < 150 K

during transient

McLarty, D.F., Samuelsen, S., and Brouwer, J.

ASME Paper FC2010-33328, June, 2010


Air

Motor

SOFC

Blower

Oxid-

izer

Oxid-

izer

Refor-

mer

Heat

Exch.

Fuel

+ H2O

Exit

Heat

Exch.Steam

Prep.

Example: Sudden Increase in Power

Integrated Stand-Alone SOFC system

• Manipulate:

• Fuel flow

• Blower power

• Bypass valve

• Control:

• System power

• Peak SOFC temperature

• SOFC temperature profile

• Perturbation:

• 25 to 70 amp current increase with PEN temperature feedback




PE

N T

em

p (

K)

Refo

rme

r

Tem

p (

K)

Time (s)

Time (s)


Integrated

SOFC

system

25 to 70 amp

current

increase

perturbation

Control actions:

© National Fuel Cell Research Center, 2011

Mueller, F., Jabbari, F., Brouwer,

J., Journal of Power Sources, Vol.

187, Iss. 2, pp. 452-460, 2009


Initial 0-s Peak 874s Final 50ksTransition 1050s

PE

N T

em

p (

K)

Curr

ent (A

)


Integrated SOFC system - 25 to 70 amp current increase

with PEN temperature feedback




Outline

• Introduction




• Summary


Summary

• Introduced importance of FC systems integration

• Developed a novel, simple but resolved, simulation

approach for steady-state & dynamic system modeling

• Demonstrated the importance of spatial and temporal

resolution of relevant physics, chemistry,

electrochemistry

• Provided examples of application, insights

• Applied tools to develop and test control systems and

strategies for integrated FC systems

• Inter-disciplinary innovations and integrated systems

study, development and demonstration are essential to

fuel cell advancement


Acknowledgements

• Funding Agencies:

• U.S. Department of Energy

• California Energy Commission

• U.S. Environmental Protection Agency

• Collaborating Faculty:

• Faryar Jabbari Joongmyeon Bae

• Keyue Smedley Scott Samuelsen

• Research Colleagues & Students:

• Randy Gemmen Ashok Rao

• Fabian Mueller Ghazal Razeghi

• Rory Roberts Travis Shultz

• Dustin McLarty Marc Carreras

• Tomohiko Kaneko Andrew Martinez

• Mu Li Hossein Ghezel-Ayagh


Acknowledgements

Participating Organizations:

• Siemens Power Corporation

• FuelCell Energy, Corp.

• National Energy Technology Laboratory

• Southern California Edison

• U.S. Department of Defense Fuel Cell Program


Renewable Systems Challenges

Wind Power – Example of Non-Coincidence with Peak

Demand

CAISO, 2007

Need some energy storage and/or dispatchable power

to shift the resource to match demand


Renewable Systems Challenges

Energy Deployment Model Results - 33% Wind Penetration

With “Deep Grid Situational Awareness” we can

automatically and instantaneously dispatch local

generation, energy storage, demand response, …


STORAGE

TANK

ADG

HOT

WATER

HEAT

EXCHANGER ANAEROBIC

DIGESTION

GAS HOLDER

SLUDGE

DIGESTER

National Fuel Cell Research Center

University of California, Irvine

BOILER

HYDROGENHYDROGEN

STORAGE

HYDROGEN

DISPENSER

FUEL

TREATMENT

AC

POWER

PROJECT

HIGH-T

FUEL CELL

PROJECT:

• Orange County Sanitation District

• Euclid Exit, I405, Fountain Valley

• Support: DOE, ARB, AQMD, CEC

• Initial Operation Underway

Renewable Energy Station

http://www.airproducts.com/


Energy Station Concept 1, 2, 3

Locally

available

feedstock:

Natural Gas,

ADG,

Landfill Gas, ….

Electricity

Heat

Hydrogen

Energy Station ConceptIntroduction and Background

1 Brouwer et al., 2001; 2 CHHN Blueprint Plan, 2005; 3 Leal and Brouwer, 2006


100 MJ

of CH4

143 MJ

of CH4

HTFC

47 MJ

electricity

η=47%

43 MJ

H2

η=100%

53 MJ high

quality heat

53%

with

TRI-

GENERATIO

N

Synergies: • Higher electrochemical efficiency (fuel utilization)

• Less electrochemical heat generation

• More internal reformation/cooling

• Less blower power

Renewable Energy Station

Synergies Produce Remarkable Performance


Status

• Wastewater Treatment 9.40

• Directed BioGas 8.90

• Hotels 2.75

• Government 2.25

• Universities 3.00

• Breweries 1.00

• Industrial 3.20

• Manufacturing 1.50

• Commercial 2.50

• Utilities 0.25

TOTAL = 34.75 MW

Sierra Nevada Brewery

Chico

SOURCE: CASFCC.ORG

Waste Water Treatment Plant

Tulare

California State University

Northridge

Sheraton Hotel

San Diego

Wastewater Treatment Plant

Santa Barbara


Status

• Wastewater Treatment 9.40

• Directed BioGas 8.90

• Hotels 2.75

• Government

2.25

• Universities

3.00

• Breweries 1.00

• Industrial 3.20

• Manufacturing 1.50

• Commercial

2.50

• Utilities 0.25

TOTAL = 34.75 MW

SOURCE: CASFCC.ORG

Stockton College

Stockton

Whole Foods

San Jose

Cox

Communications

San Diego, Rancho

Santa Margarita

St. Helena Hospital

St. Helena

Albertsons

San Diego


500 kW, June 2009

500 kW, Feb 2010

400 kW, Jan 2010

Status

400 kW, July 2008

Status


Backup Slides


Introduction and Background

Poly-generation of Power, Heat and H2

• Advantages: 4, 5, 6

• H2 production is at the point of use averting emissions and

energy impacts of hydrogen and electricity transport

• Fuel cell produces sufficient heat and steam as the primary

inputs for the endothermic reforming process

• Synergistic impacts of lower fuel utilization increases overall

efficiency (i.e., higher Nernst Voltage, lower polarization

losses, lower cooling requirement and associated air blower

parasitic load)

• Potential Disadvantage:

• May not be compatible with carbon sequestration4 Leal and Brouwer, 2006; 5 O’Hayre, R., 2009; 6 Margalef et. al, 2008


• EXAMPLE: Efficiency of a Poly-Generating Hydrogen

Energy Station (H2ES) without valuing heat

Poly-Generation Analyses

Electricity

production with

state-of-the-art

natural gas

combined cycle

Centralized SMR

Plant

(H2 production)

(Case: H2ES)

Poly-generating

HTFC

Fuel

Fuel

Fuel

Electricity

Hydrogen

η el,1 = 61.2%η el,2 = 51.7%η el,3 = 58.4%

η H2,1 = 80.9%η H2,2 = 54.9%η H2,3 = 83.5%

η el,pp = 60%

η H2,SMR = 79%

ηtot = 69.5%


• Electrochemistry & Reformation Synergy – Air Flow

30

40

50

60

70

80

90

100

0.4 0.5 0.6 0.7 0.8

Air

flo

w in

[km

ol/

hr]

Fuel Utilization Factor

Factor #1electrochem

. heat

Poly-Generation Analyses

Factor#2reformation

cooling


Poly-Generation Renewable Energy System

Orange County Sanitation District (OCSD) Project

Sponsors & Participants


OCSD Project Status

• Factory Test in Danbury, CT completed


OCSD Project Status

• Installation Complete (except ADG skid), Shakedown,

Initial Operation Underway Orange County

Sanitation

District

(OCSD)

Renewable H2

Filling Station

ADG fueled

DFC-H2®

Production Unit


1

1.5

2

2.5

3

3.5

4

4.5

0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2

Normalized Flow

Pre

ss

ure

Ra

tio 0.60

0.70

0.80

0.90

1.00

System

Normalized

RPMSurg

e Lin

e

1

1.5

2

2.5

3

3.5

4

4.5

0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2

Normalized Flow

Pre

ss

ure

Ra

tio 0.60

0.70

0.80

0.90

1.00

System

Normalized

RPM

1

1.5

2

2.5

3

3.5

4

4.5

0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2

Normalized Flow

Pre

ss

ure

Ra

tio 0.60

0.70

0.80

0.90

1.00

System

Normalized

RPMSurg

e Lin

e

Complementary Dispatch

0 50000 100000 150000 200000160

162

164

166

168

170

FC

Pow

er

[kW

]Time [sec]

Experiment

Model

FC Power

Jan 2001

0

20

40

60

80

100

120

140

160

180

200

Jan-7 Jan-9 Jan-11 Jan-13 Jan-15 Jan-17 Jan-19 Jan-21

Day

Po

wer

[kW

]

0

5

10

15

20

25

30

35

40

45

50

Co

mp

. in

let

Tem

p.

[C]

Experiments &

Models suggest good

dynamic response is

possible

http://www.fuelcellenergy.com/index.php

http://www.sce.com/sc3/


SCE 220 kWe PSOFC/GT Performance - SAT1

0

20

40

60

80

100

120

140

160

180

0 50 100 150 200 250

Time, hours

[Since June 3, 2000]

Po

wer

, kW

e an

d

Eff

icie

ncy

, %

0

200

400

600

800

1000

1200

Tem

per

atu

re,

C

SOFC DC kWe MTG AC kWe AC Efficiency % SOFC Temperature Ambient Temp. * 10

STOP

STOP- Low Terminal Voltage

(Power lead failure)

EXAMPLE RESULTS

SOFC DC kW MTG AC Kw AC EFFICIENCY % SOFC TEMP AMBIENT TEMPx10

• UNATTENDED OPERATION

• SUNDAY

• SHUT DOWN CONTROL “EXERCISED”

• SUCCESSFUL

4

3

2

5

1

(1) STOP: HIGH POWER LEAD RESISTANCE6

© National Fuel Cell Research


AIR

EXHAUST

OXIDIZER

RECUPERATOR

COMPRESSOR TURBINE

SOFC

FUEL

MTG-SOFC PRESSURIZED HYBRIDMTG-SOFC PRESSURIZED HYBRID



MCFC

EXHAUST

AIR

COMPRESSORTURBINE

FUEL

OXIDIZER

WATER

HEAT

RECOVERY

UNIT

MOLTEN CARBONATE FUEL CELL (MCFC)MCFC-MTG ONE ATMOSPHERE HYBRID


© National Fuel Cell Research Center, 2011 84/66© National Fuel Cell Research MO2512

73000

250KW DFC® STACK INTEGRATED WITH A CAPSTONE 330 MICROTURBINE

• 2,900 HOURS

• 209kW (NET AC)

– FC: 206.0 kW

– MTG: 9.5 kW

– PP: 6.5 kW

• NET EFFICIENCY: 51.7%

FUEL CELL ENERGY

U.S. DEPARTMENT OF ENERGY

VISION 21

MCFC-MTG ONE ATMOSPHERE HYBRID


Dynamic Modeling Results

0 50000 100000 150000 2000000.6

0.61

0.62

0.63

0.64

0.65

FC

Voltage [

V]

Time [sec]

Experiment

Model

Siemens Integrated

SOFC SystemSingle Cell

MCFC Test

Stand

0 1 2 3 4 5 618.5

19

19.5

20

20.5

Time (Hr)

Mo

du

le P

ow

er

(kW

)

Siemens/SCE 220

kW

SOFC/GT Hybrid


Example: Load Increase

10-2

10-1

100

101

102

103

104

100

150

200

250

300

Time (s)

Power Demand (kW) Power Out (kW) Voltage (V) Current/4 (A)

10-2

10-1

100

101

102

103

104

0

0.2

0.4

0.6

0.8

1

Time (s)

RPM/80 (kRPM) FC Fuel Flow (mol/s) FC Bypass

10-2

10-1

100

101

102

103

104

-5

0

5

Time (s)

Err

or

Power (kW)*100

Electrolyte Temp (K)Combustor Temp/2 (K)

10 kW per second: 150 to 200 kW load increase


Example: Load Following and

Disturbance Rejection

System response to a dynamic load, temperature variation, and large fuel disturbance

0 500 1000 1500 2000 2500 3000 3500 4000150

160

170

180

190

200P

ow

er

Dem

an

d (

kW

)

Time (s)

0 500 1000 1500 2000 2500 3000 3500 40000

0.5

1

Fu

el

Mo

le F

racti

on

Time (s)

XCH4

XN2

0 500 1000 1500 2000 2500 3000 3500 4000

280

290

300

310

Am

b T

em

p (

K)

Time (s)

0 500 1000 1500 2000 2500 3000 3500 4000-5

0

5

Time (s)

Err

or

Power (kW)*100 Electrolyte Temp (K) Combustor Temp/4 (K)

3 sec

Sampling


Additional Information

Publications

• Roberts, R.A., Brouwer, J., Liese, E., Gemmen, R.S., Dynamic Simulation of Carbonate Fuel Cell-Gas Turbine Hybrid Systems, ASME Journal of Engineering for Gas Turbines and Power, Volume 128, Issue 2, pp. 294-301, April, 2006.

• Roberts, R.A., and Brouwer, J., Dynamic Simulation of a 220kW Solid Oxide Fuel Cell Gas Turbine Hybrid System with Comparison to Data, ASME Journal of Fuel Cell Science and Technology, Volume 3, Issue 1, pp. 18-25, February, 2006.

• Mueller, F., Brouwer, J., Jabbari, F., and Samuelsen, G.S., Dynamic Simulation of an Integrated Solid Oxide Fuel Cell System Including Current-Based Fuel Flow Control, ASME Journal of Fuel Cell Science and Technology, Volume 3, Issue 2, pp. 144-154, May, 2006.

• Brouwer, J., Jabbari, F., Leal, E.M. and Orr, T., Analysis of a Molten Carbonate Fuel Cell: Numerical Modeling and Experimental Validation, Journal of Power Sources, Volume 158, Issue 1, pp. 213-224, July, 2006.

• Maclay, J.D., Brouwer, J., and Samuelsen, G.S., Dynamic Analyses of Regenerative Fuel Cell Power for Potential use in Renewable Residential Applications, International Journal of Hydrogen Energy, Volume 31, pp. 994-1009, 2006.

• Roberts, R.A., Brouwer, J., Jabbari, F., Junker, T., and Ghezel-Ayagh, H., Control Design of an Atmospheric Solid Oxide Fuel Cell/Gas Turbine Hybrid System: Variable versus Fixed Speed Gas Turbine Operation, Journal of Power Sources, Volume 161, pp. 484-491, 2006.

• Kaneko, T., Brouwer, J., and G.S. Samuelsen, Power and Temperature Control of Fluctuating Biomass Gas Fueled Solid Oxide Fuel Cell and Micro Gas Turbine Hybrid System, Journal of Power Sources, Volume 160, Issue 1, pp. 316-325, 2006.

• Traverso, A., Massardo, A., Roberts, R.A., Brouwer, J., and Samuelsen, G.S., Gas Turbine Assessment for Air Management of Pressurized SOFC/GT Hybrid Systems, ASME Journal of Fuel Cell Science and Technology, Volume 4, pp. 373-383, November, 2007.

• Mueller, F., Brouwer, J., Kang, S.G., Kim, H.-S., and Min, K.D., Quasi-Three Dimensional Dynamic Model of a Proton Exchange Membrane Fuel Cell for System and Controls Development, Journal of Power Sources, Volume 163, Issue 2, pp. 814-829, 2007.

• Mueller, F., Jabbari, F., Gaynor, R.M., and Brouwer, J., Novel solid oxide fuel cell system controller for rapid load following, Journal of Power Sources, Volume 172, pp. 308–323, 2007.

• Roberts, R.A., Brouwer, J., Liese, E., Gemmen, R.S., Dynamic Simulation of Carbonate Fuel Cell-Gas Turbine Hybrid Systems, ASME Journal of Engineering for Gas Turbines and Power, Volume 128, Issue 2, pp. 294-301, April, 2006.


Additional Information

Publications (cont’d)

• Mueller, F., Brouwer, J., Jabbari, F., and Samuelsen, G.S., Dynamic Simulation of an Integrated Solid Oxide Fuel Cell System Including Current-Based Fuel Flow Control, ASME Journal of Fuel Cell Science and Technology, Volume 3, Issue 2, pp. 144-154, May, 2006.

• Roberts, R.A., and Brouwer, J., Dynamic Simulation of a 220kW Solid Oxide Fuel Cell Gas Turbine Hybrid System with Comparison to Data, ASME Journal of Fuel Cell Science and Technology, Volume 3, Number 1, pp. 18-25, February, 2006.

• Meacham, J.R., Jabbari, F., Brouwer, J., Samuelsen, G.S., and Mauzey, J.L., Analysis of Stationary Fuel Cell Dynamic Ramping Capabilities and Ultra Capacitor Energy Storage using High Resolution Demand Data, Journal of Power Sources, Volume 156, Issue 2, pp. 472-479, July, 2006.

• Brouwer, J., Jabbari, F., Leal, E.M. and Orr, T., Analysis of a Molten Carbonate Fuel Cell: Numerical Modeling and Experimental Validation, Journal of Power Sources, Volume 158, Issue 1, pp. 213-224, July, 2006.

• Freeh, J.E., Pratt, J.W., and Brouwer, J., “Development of a Solid-Oxide Fuel Cell / Gas Turbine Hybrid System Model For Aerospace Applications,” ASME Paper Number GT2004-53616, June, 2004.

• Roberts, R., Mason, J., Jabbari, F., Brouwer, J., Samuelsen, S., Liese, E. and Gemmen, R., Inter-Laboratory Dynamic Modeling of a Molten Carbonate Fuel Cell, ASME Paper Number 2003-GT-38774, June, 2003.

• Gemmen, R, Liese, E., Rivera, J., Jabbari, F, and Brouwer, J., Development of Dynamic Modeling Tools for Solid Oxide and Molten Carbonate Hybrid Fuel Cell Gas Turbine Systems, ASME Paper Number 2000-GT-554, May, 2000.

• Liese, E. A., Gemmen, R. S., Jabbari, F., and Brouwer, J., Technical Development Issues and Dynamic Modeling of Gas-Turbine and Fuel Cell Hybrid Systems, ASME Paper Number 99-GT-360, January, 1999. Roberts, R.A., Brouwer, J., Liese, E., Gemmen, R.S., “Dynamic Simulation of Carbonate Fuel Cell-Gas Turbine Hybrid Systems,” ASME Paper Number GT2004-53653, June, 2004.

• Yuan, L., Brouwer, J., and Samuelsen, G.S., “Dynamic Simulation of an Autothermal Methane Reformer,” 2nd International Conference on Fuel Cell Science, Engineering and Technology, ASME Paper Number FuelCell2004-2518, June, 2004.

• Leal, E.M, Jabbari, F., and Brouwer, J., "Dynamic Numerical Modeling and Experimental Validation of a Molten Carbonate Fuel Cell," Proceedings of the 3rd International Conference on Fuel Cell Science, Engineering and Technology, ASME Paper Number FC2005-74104, May, 2005.

• Roberts, R.A., Brouwer, J., Liese, E., Gemmen, R.S., “Development of Controls for Dynamic Operation of Carbonate Fuel Cell Gas Turbine Hybrid Systems,” ASME Paper Number GT2005-68774, June, 2005.

Documents

Fuel Cell & Hybrid Fuel Cell Gas Turbine System Design