SOFC Power Systems M.J. Day, Principal Investigator 12 th Annual - - PowerPoint PPT Presentation

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SOFC Power Systems M.J. Day, Principal Investigator 12 th Annual - - PowerPoint PPT Presentation

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12 th Annual SECA Workshop: July 28, 2011 Invent, Develop, Deliver. Validation of Novel Planar Cell Design for Megawatt-Scale SOFC Power Systems M.J. Day, Principal Investigator 12 th Annual SECA Workshop Pittsburgh, PA July 28, 2011 12 th

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Invent, Develop, Deliver.

12th Annual SECA Workshop: July 28, 2011

Validation of Novel Planar Cell Design for Megawatt-Scale SOFC Power Systems

M.J. Day, Principal Investigator 12th Annual SECA Workshop Pittsburgh, PA July 28, 2011

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12th Annual SECA Workshop: July 28, 2011

  • Achieved ISO 9001:2008 certification for all

products and processes within NexTech

  • Launched hydrogen safety sensor product(s), and

recently passed UL/ATEX certification tests

  • Launched interconnect coating product
  • Continued progress made on SOFC stack

technology development

NexTech News

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12th Annual SECA Workshop: July 28, 2011

Outline

  • Project Details, Objectives, Conclusions
  • Introduction to FlexCell
  • Status of NexTech’s SOFC Stack Technology
  • Results of SECA Project
  • Future Work
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Project Details, Objectives, and Conclusions

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U.S. Department of Energy (SECA)

  • DOE Contract Number: DE-NT0004113
  • Project Monitor: Briggs White
  • Phase I: 1-Oct-08 to 31-Mar-10
  • Phase II: 1-Apr-10 to 30-Sep-11

State of Ohio (Third Frontier Program)

  • Cell Manufacturing for 100+ kW SOFC Power Generation Systems
  • ODOD Contract Number: TECH 08-057

NexTech’s Team

  • Principal Investigator: Mick Day
  • NexTech Contributors: Scott Swartz, Lora Thrun, Kellie Chenault
  • Subcontractor: Ohio State University (Professor Mark Walter)

Project Details

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12th Annual SECA Workshop: July 28, 2011

Overall Project Goal

  • Validate performance, robustness, cost and scalability of

NexTech’s FlexCell planar cell design for coal-based SOFC power systems

Phase I Objectives

  • Demonstrate that high performance can be achieved in

FlexCells made with YSZ as the electrolyte material

  • Demonstrate that FlexCells have sufficient mechanical

robustness for SOFC applications

  • Demonstrate potential of achieving cell manufacturing cost
  • f less than $50/kW

Project Objectives

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  • Fabrication methods for ScSZ-based FlexCells were

successfully transferred to YSZ-based FlexCells.

  • YSZ-based FlexCells successfully scaled to 500-cm2

area.

  • High performance in YSZ-based FlexCells has been

demonstrated at the single-cell (and stack) level.

  • Finite element analysis is an effective design tool

for mechanically robust FlexCell architectures.

  • Cell manufacturing cost was estimated to be

$51/kW at 250 MW/year scale

Conclusions

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Introduction to the FlexCell

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Attributes

  • Thin-electrolyte for high

performance

  • Small repeat units for high

power density

  • Dense perimeter for ease
  • f sealing
  • Thin electrodes to

facilitate gas diffusion

  • Thin anode for redox

cycling tolerance

  • Electrode material flexibility

Introduction to the FlexCell

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High power density and high fuel utilization Internal Methane Reforming

0.0 0.2 0.4 0.6 0.8 0.0 0.3 0.6 0.9 1.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Power Density (W/cm2) Cell Potential (volts) Current Density (A/cm2)

0.725 W/cm2 (0.701 V @ 1.036 A/cm2) 81% fuel utilization

T = 800ºC (H2/N2)

Performance Attributes

0.0 0.1 0.2 0.3 0.4 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.1 0.2 0.3 0.4 0.5 0.6

Power Density (W/cm2) Cell Potential (volts) Current Density (A/cm2)

0.60 V @ 0.53 A/cm2 UF = 95% 60% Efficiency A = 81 cm2, T = 800ºC, H2O/CH4 = 3/1

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0.0 0.2 0.4 0.6 0.8 1.0 3,000 6,000 9,000 12,000 15,000

Potential (volts) Time (hours)

T = 750ºC, J = 0.7 A/cm2, H2/air Single-Cell Test with Inconel-601 Manifolds Degradation rate = 0.67 μV/hour (after first 100 hours)

Durability Attributes

0.0 1.0 2.0 3.0 4.0 50 100 150 200 250 300 350

Stack Potential (volts) Time (hours)

100 mV/cell degradation T = 800ºC, J = 350 mA/cm2

Redox Cycling Capability (3-cell stack, Hybrid Cells) Long-Term Durability (Hybrid Cell)

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100 200 300 400 500 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 100 200 300 400 500 600 Power (watts) Cell Potential (volts) Current (amps)

426 watts 562 A @ 0.759 V UF = 71% T = 800ºC Anode: 11.0 lpm H2/N2 (50%) Cathode: 40 lpm air

Total Cell Area: 1200 cm2 Active Cell Area: 800 cm2

Scalability to Large Areas for Higher Power Stacks

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0.0 1.0 2.0 3.0 4.0 100 200 300 400 500 Potential (volts) Time (hours)

T = 800ºC J = 0.203 A/cm2 UF = 65% 50 pmm H2S Fuel

34.6% H2 8.4% CO 30.0% H2O 8.1% CO2 18.9% N2

Sulfur Tolerant Stack Operation (3-Cell Stack)

Simulated ATR Reformate 50 ppm H2S, UF = 65%

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Status of NexTech’s SOFC Stack Technology

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14.6 by 22.2 cm 18.4 by 29.2 cm

FlexCell for 1-2 kW stacks FlexCell for 5-10 kW stacks

Stack-Intent FlexCells

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1-kW Scale Stack Platform

Total Cell Area: 320 cm2 Active Cell Area: 160 cm2 24-Cell Stack

200 400 600 800 1000 1200 5 10 15 20 25 30 10 20 30 40 50 60 Stack Power (watts) Stack Potential (volts) Current (amps) 1.04 kW @ 0.78 V/cell 70% fuel utilization

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200 400 600 800 1000 1200 5 10 15 20 25 30 10 20 30 40 50 60 Power (watts) Potential (volts) Current (amps)

Stack #128 Stack #133 Stack #134 Stack #138 Stack #142

Stack Temperature = 800ºC 26.8 lpm H2/N2, 120 lpm air

Reproducibility

  • f 24-Cell Stacks
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5-10 kW Scale Stack Platform

Total Cell Area: 540 cm2 Active Cell Area: 300 cm2

100 200 300 400 0.0 1.0 2.0 3.0 4.0 50 100 150 200 Stack Power (watts) Stack Potential (volts) Current (amps) 344 W @ 172 A UF = 91.5 percent 48.5% efficiency

3-Cell Stack

3-Cell Stack

150 300 450 600 750 900 1050 1200 2 4 6 8 10 12 14 25 50 75 100 125 150 Stack Power (watts) Stack Potential (volts) Current (amps) 1033 W @ 132 A 0.782 V/cell UF = 70.1 percent

10-Cell Stack

10-Cell Stack

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0.0 1.0 2.0 3.0 4.0 30 60 90 120 150 Stack Potential (volts) Current (amps)

first pole curve after 1st cycle after 2nd cycle UF = 70% (J = 0.441 A/cm2) First pole curve: 2.28 volts After first cycle: 2.24 volts After second cycle: 2.22 volts

T = 790°C Anode: 7.88 lpm H2/N2 Cathode: 28 lpm air

Degradation @ UF = 70% First Cycle: 1.47% Second Cycle: 1.04%

Thermal Cycling (large-area 3-cell stack)

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New Stack Design (higher efficiency)

0.0 0.1 0.2 0.3 0.4 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.1 0.2 0.3 0.4 0.5 Power Density (W/cm2) Potential (V/cell) Current Density (A/cm2) H2/N2 fuel, T= 800°C 9-Cell Stack (New Design) 10-Cell Stack (Original Design)

UF = 70%

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0.60 0.65 0.70 0.75 0.80 0.85 0.90 12 24 36 48 60 72 Potential (volts/cell) Time (hours) Stack: UF = 79.6% LHV Efficiency: 46.0% 9-Cell Stack (160-cm2 active area) T = 800°C, J = 0.30 A/cm2, 330 watts Fuel 42% H2 (2995 sccm) 11% CO (785 sccm) 16% CO2 (1141 sccm) 31% H2O (2210 sccm)

High Efficiency Stack Operation

Simulated Steam Reformate UF = 79.6% LHV Efficiency = 46.0%

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12th Annual SECA Workshop: July 28, 2011

  • Developing interconnect coating technology to

enable long-term durability and thermal cycling

  • Completing 1-2 kW stack platform, focusing on

efficiency, durability and thermal cycling

  • Breadboard demonstrations of SOFC power

generation using military logistic fuels

  • Continuing development of 5-10 kW stack

platform

  • Offering 1-kW scale stacks for evaluation by

potential partners

Ongoing Stack Development Activities

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Fabrication and Testing

  • f YSZ-Based FlexCells

(SECA Project)

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Fabrication of YSZ-Based FlexCells

Architecture Variables

  • Support thickness: 80-160 μm
  • Membrane thickness: 24-32 μm
  • Percent thin membrane in active

region: 65-75 percent

  • Support mesh pattern/geometry
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YSZ Based FlexCell

0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.3 0.6 0.9 1.2 1.5 Power Density (W/cm2) Cell Potential (volts) Current Density (A/cm2)

850ºC: ASR = 0.20 Ω-cm2 800ºC: ASR = 0.27 Ω-cm2 750ºC: ASR = 0.42 Ω-cm2

A = 28 cm2 Fuel: 450 sccm H2

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YSZ versus ScSZ (Identical Geometry)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.4 0.8 1.2 1.6

Cell Potential (volts) Current Density (A/cm2)

ScSZ Electrolyte YSZ Electrolyte YSZ Electrolyte 850ºC 750ºC

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0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2

Power Density (W/cm2) Cell Potential (volts) Current Density (A/cm2)

T = 800ºC, UF = 70% 475 mW/cm2 at 0.7 volts 287 mW/cm2 at 0.8 volts

Constant Utilization Pole Curve Data

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Large-Area YSZ-Based FlexCells

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40 80 120 160 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 40 80 120 160 200 Power (watts) Cell Potential (volts) Current (amps)

135 watts (0.70 V @ 190 A) 73% fuel utilization T = 800ºC Fuel: H2/N2

Large-Area YSZ-Based FlexCell

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Future Work

  • Fabrication of YSZ-based FlexCells for stack

testing at NexTech

  • Long-term testing of three-cell stacks with

simulated coal gas

  • Testing of full-scale SOFC stacks made with

YSZ-Based FlexCells

  • Preparation of the Final Report