Natural Gas-Fueled Distributed Generation SOFC SystemsPerformance and Cost of Electricity

Prepared for:10th Annual SECA Meeting10th Annual SECA MeetingPittsburgh, PA, USA

Date: July 14th, 2009

4910 163rd Avenue NE, Redmond, WA 98052, USAt: 206 229 6882; e: jant@jthijssen.com

Agenda

1 Background Objective and Approach

System Definition

1

2

Background, Objective, and Approach

3 Heat & Material Balances

4 Cost AnalysisCos a ys s

5 Conclusions

Interest in fuel cells for distributed generation has Background

gwaxed and waned.

• Around 2000, interest in DG peaked:Around 2000, interest in DG peaked:– Low natural gas cost (Henry Hub ~$2/MMBTU)– Prospect of suitable new generation technologies

• Fuel cells were thought to be a good fit:– Low emissions– High efficiency– Small scale

• But:– Fuel cells were not ready

$ /– Natural gas cost rose (Henry Hub >$4/MMBTU)

DOE wanted to understand the performance & cost Objective

pstate-of-the-art SOFC in DG applications.

• Basis for analysis:Basis for analysis:– 5 MWe grid-connected system– SOFC stack technology available commercially 2020– Relevant energy cost (EIA projections)– Appropriate operating strategies (incl. CHP) – Consider cost implications of DG operation

• Based on detailed performance & cost analysis• Allow comparison with central generation options

such as IGCC and IGFC• Consider potential impact of CCS requirements

We used our established fuel cell system model to Approach

yproject NG DG SOFC system performance and cost.

Define SystemDefine System

Analyze Stack Analyze Stack PerformancePerformance

Compute System Heat & Material Balances

Compute System Heat & Material Balances

System Efficiency, Emissions

Obtain Sizing ParametersObtain Sizing Parameters

Estimate System CAPEX & OPEXEstimate System CAPEX & OPEX

LCOECAPEX & OPEXCAPEX & OPEX

Consider Impact of Carbon Capture Separately in Sensitivity AnalysisSeparately in Sensitivity Analysis

Agenda

1 Background Objective and Approach

System Definition

1

2

Background, Objective, and Approach

3 Heat & Material Balances

4 Cost AnalysisCos a ys s

5 Conclusions

The application and scale dictates a simple and System Definition Design Considerations

pp pefficient flowsheet.

• Stack technology: atmospheric w/ separated flowsStack technology: atmospheric w/ separated flows• Relatively small system:

– Simple maintenanceSimple maintenance– Easy siting / permitting– Low cost

• This means:– Avoid wet scrubbing / adsorption processes– Minimize # of unit operations– Minimize water consumption– Avoid noisy components (compressors)

System Definition Process Flow Diagram

SOFCCathodeAir Air PreheatAnode

Cathode

Steam Superheat

Steam Generator

Water

Air Air Preheat

SuperheatGenerator

PreheatNatural

SMRPreheatGas

SMR

Tail Gas

Burner

Exhaust

The SOFC stack assumptions used are consistent System Definition Stack Assumptions

pstate-of-the-art stacks and with other recent studies.

• Performance consistent with state-of-the-art planar Performance consistent with state of the art planar technology:– Polarization similar to current performance– Durability and temperature range consistent with DOE

program targets for 2015C h ll (125 2) d l (2000 2) ll– Case with small (125 cm2) and large (2000 cm2) cells

Fuel Utilization 70% / 86%

Key Stack Performance Characteristics

Stack Temperature 650 – 800°C(single pass / overall)

Cathode Stoichiometry

Anode Recycle

70% / 86%

2 86

60%Cell Voltage

Stack Temperature

0.83V

650 – 800 C

Cell Current Density 0 50 A/cm2 Cathode Stoichiometry 2.86Cell Current Density 0.50 A/cm2

Several carbon capture options are technically System Definition Carbon Capture Options

p p ypossible.

• Sorbent capture from exhaustSorbent capture from exhaust• Water gas shift + capture from syngas• Oxyfuel combustion of anode exhaust + whole gas Oxyfuel combustion of anode exhaust + whole gas

capture

Agenda

1 Background Objective and Approach

System Definition

1

2

Background, Objective, and Approach

3 Heat & Material Balances

4 Cost AnalysisCos a ys s

5 Conclusions

To achieve high efficiency, significant recuperation Heat Balance

g y, g pis necessary.

Sankey Diagram for Baseline 5 MW NGDG SOFC System

0 8 MW O h

2.5 MW Thermal Losses

1.3 MWth Chemical Recuperation

Heat

Fuel

0.8 MW Other Parasitics

5.5 MWth Thermal Recuperation

5.2 MWe Net

9.1 MW Gas Feed

5.8 MWeDC P

Fuel Cell

Stack

Steam Methane Reformer e

PowerFeed DC Power

1.9 MW Syngas Recycle

StackReformer

Syngas recycle is critical to the system water Water Balance

y g y ybalance: it provides steam for the reformer.

Water Management (5 MW System)

0 4 kg/s 0.03 kg/s Make- Up 0.4 kg/s

moisture to exhaust

Make- Up Water

Steam Methane Reformer Net Water

0.52 kg/s in SyngasRecycle

Net Water consumption: ~800 gal/day

(or 7 gal/MWhnet)y ( g / net)

~58% efficiency (HHV) is achievable in simple-Performance Analysis Results

y ( ) pcycle configuration.

System Performance (5 MW DG System)

Fuel Utilization (single pass, overall)

Cathode StoichiometryAnode Recycle

70% / 86%

2.8660%

Fuel Cell Stack

St / C b R ti 3R f

Cell VoltageStack Temperature

0.83 V650 – 800°C

Fuel Cell Gross Power 5.7 MWSteam / Carbon RatioMethane SlipWater Use

37%

800 gpd

Reformer

Blower Power 230kWBoPOther Parasitic LoadsBlower Power

50 kW230kWBoP

Exhaust Temperature 315 °CSystemSystem Efficiency (HHV Basis) 57.6%y y ( )

Cell voltage and stack temperature rise have the Performance Analysis Sensitivity Analysis

g pgreatest impact on efficiency.

Sensitivity of System Efficiency (5 MW DG System)y y y (5 MW G Sy )

Cell Voltage 0.77 0.85 VFuel Cell

57.6%

Anode Recycle

Stack ∆T

40 - 75%

75 – 200°CStack

Fuel Utilization 60 %– 85%

Stack Heat LossSteam / Carbon Ratio

50 %– 200%2 – 3.5Reformer

Fuel Utilization 60 %– 85%

Other Parasitic Loads

Blower Efficiency

25 – 250 kW

50%- 85%

BoP

56% 58%54% 60%56% 58%54% 60%

Oxyfuel combustion & whole anode gas capture Cost Analysis Results LCOE Impact of CO2 Capture

y g plikely presents the most realistic CCS option.

Impact of CCS on Efficiency (Maximum 30 gCO2/kWh Emissions)

40%

50%

60%

Effic

ienc

y V

)

20%

30%

0%

Sys

tem

E(%

HH

-10%

0%

10%

Baseline Shift & Absorb End-of-Pipe Oxy-Fuel

Net

MEA

With CSSNo CSS With CSSNo CSS

Agenda

1 Background Objective and Approach

System Definition

1

2

Background, Objective, and Approach

3 Heat & Material Balances

4 Cost AnalysisCos a ys s

5 Conclusions

The cost analysis followed a well-established Cost Analysis Results CAPEX Approach

ymethodology, building on several previous studies.

• Bottom-up activity-based stack cost analysisBottom up activity based stack cost analysis• BoP equipment costs via scaling from quotes• Costs were escalated to 2007 based on DoC’s PPICosts were escalated to 2007 based on DoC s PPI• A uniform 42.5% installation factor was used

The cost analysis indicates that installed CAPEX Cost Analysis Results CAPEX

ywould be around $870/kW

Capital Cost Estimates (5 MW DG System, 2007$)

800900

1000

net)

QC, Assembly, InstallationControls Inverter

500600700800

t ($/

kWn Controls, Inverter,

InterconnectionRotating Equipment

Th l M t

200300400500

ital C

ost Thermal Management

Reformer

0100200

Cap

i

Stack Infrastructure

SOFC Stack

Small Cells Large Cells

The LCOE from NGDG SOFC systems ranges from 7 Cost Analysis Results LCOE

y gto 9.5 cents/kWh.

NGDG System LCOEy

89

10

Fixed O&M

5678

¢/kW

h)

Non-Fuel Variable O&M

1234

LCO

E (

Fuel

CAPEX

01

Baseload 12 on / 12 off

CHPoff

Gas price, carbon capture, and stack degradation Cost Analysis Results LCOE Sensitivity Analysis

p , p , gmost strongly impact LCOE for DG systems.

Sensitivity of LCOE (5 MW DG System)

Gas Price (2 5 - 12 $/MMBTU)

A id d Di t C t (0 2 ¢/kWh)Stack Degradation (0, 1.5%)

Carbon Capture (0 - 90%)Gas Price (2.5 - 12 $/MMBTU)

Capacity Factor (60 - 95%)CAPEX (660 - 1220 $/kW)

Avoided Distr. Cost (0 - 2 ¢/kWh)

4 5 6 7 8 9 10 11 12

System Efficiency (52 - 61%)

Agenda

1 Background Objective and Approach

System Definition

1

2

Background, Objective, and Approach

3 Heat & Material Balances

4 Cost AnalysisCos a ys s

5 Conclusions

Technically spectacular NGDG SOFC systems Conclusions

y p yappear feasible...

• State-of-the-art SOFC enable highly efficient, State of the art SOFC enable highly efficient, simple-cycle, systems:– ~58% efficiency (HHV basis)– Water use ~7 gal/MWh– CO2 emissions 340 g/kWh (CCS technically possible)– Very low noise, local air emissions

• But degradation should be reduced to 0 5%/1 000 h l~0.5%/1,000 hrs or less

… and in some selected market segments their cost Conclusions

gcould be attractive.

• In high-volume production:In high volume production:– CAPEX ~$870/kW (2007$)– LCOE 7.2 – 9.3 ¢/kWh/– Strong function of gas price, capacity factor

• This range is likely competitive in selected market segments (CHP, incentives, local conditions)

• It is not broadly competitive with central generation• If deep carbon reductions are required(>60%):

– CCS would be required – NG DG would likely be uncompetitive

Acknowledgement

• Thanks to Wayne Surdoval and Mark Williams for Thanks to Wayne Surdoval and Mark Williams for guidance,

• to Jim Powers and Phil Khore for input in pformulating the analysis assumptions,

• And to numerous others for feedback• Carried out under a DOE subcontract to RDS

(#41817M2846)

Th k Y !Thank You!