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Vermelding onderdeel organisatie
13 May 2013
1
Solid Oxide Fuel Cell systems and Renewable Energy sources
P V Aravind, Assistant Professor, TU Delft
The Netherlands (on sabbatical at Imperial College London this academic year)
2
Future Energy Mix and Biofuels
• Biomass (mainly waste) will/might get increasingly important as an energy source
• Fossil fuels will still be relevant
• Biomass is storable
• Competing uses: biomass for chemicals or energy?
• Electricity and transportation fuel production from biomass – widely studied and already demonstrated
• Efficiency increase will be of importance
• Sanitation systems- potential exists for biofuel production
Biofuels
• Biomass
• Biogas
• Biosyngas
• Hydrogen
• Ammonia
• Ethanol
• Methanol
• Char ……..
• As biomass will be in limited supply, efficient utilization will be of utmost importance
• Renewable fuel production possible with electrolysis, co-electrolysis and fuel assisted electrolysis- an energy storage option for renewable energy future
3
4
Solid Oxide Fuel Cell
•SOFCs work at high temperatures - 500 oC to 1000 oC •Electrical efficiencies- 45 to 60% •Fuel is never completely utilized and the flue gas can be combusted •Can operate with different biofuels
5
fuel
air flue gas
G Gas Turbine
SOFC
HR
HR
Heat Recovery Fuel Cell
Gas Turbine
Heat flow
SOFC-GT system
• If the SOFC is at high pressure , outlet streams can be fed to a gas turbine • SOFC-GT systems can reach efficiencies as high as 70-80% • They can still be connected with other bottoming cycles
6
Stationary systems
Power plant output [MW]
100050010050101 50.50.1
Eff
icie
ncy [
%]
1520
30
40
50
60
70
steam
power
plant
gas turbine
power plant
micro GT
PEM
combined-cycle
power plantSOFC
diesel engine
spark ignition engine
SOFC-GT system efficiencies with different biofuels
Fuel Energy Efficiency
Methane 78.3
Hydrogen 69.0
Ammonia 74.7
Ethanol 75.5
Methanol 73.1
H. C. Patel, T. Woudstra, P. V. Aravind, Thermodynamic Analysis of Solid Oxide Fuel Cell Gas Turbine Systems Operating with Various Biofuels, Fuel Cells, Volume 12, Issue 6, pages 1115–1128, December, 2012
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Our focus
• Development of high efficiency systems for biofuels
• Waste to energy and resources
• Stationary and mobile applications
• Aircraft and marine propulsion
• A special focus on biomass gasifier-SOFC systems
• Our projects include • Biomass gasifier-SOFC system development
• Waste water treatment- Biogas and Ammonia production for SOFCs together with fertilizer production
• Biofuels and fuel cells for aircrafts
• ……………
9
What we do- an example: Gasifier-SOFC systems
• Focus on biomass gasifier-SOFC-GT systems
• Studies on electrochemistry of fuel oxidation:
-Impedance spectroscopy
-Chem. eq. calculations
-Electrochemistry integrated CFD
• High temperature gas cleaning for SOFCs
• SOFC cell and stack testing
• Detailed system studies
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SOFCs fed with biosyngas
Biomass Gasifier Electricity SOFC/
SOFC+GT
• Sustainable high efficiency electricity production • Few kW to few MW systems- • Close to coal gasification and co-gasification based systems (SECA focus)
Knowledge developed/to be developed on • Type of gasifier • Choice of SOFC • Detailed understanding on the influence of contaminants • Gas cleaning • System thermodynamics, System dynamics, System integration
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Research Approach
• Started with system studies
• Influence of gas composition on anodes (impedance and IV measurements)
• Influence of contaminants on anodes ( equilibrium calc., Impedance and IV measurements, surface analysis)
• Gas cleaning
• System integration (system thermodynamics, integrated exps.)
12 Challenge the future
Energy System Thermodynamics at TU Delft
• Modelling Packages used - Cycle Tempo and Aspen
• Cycle Tempo- An in-house product for second law
analysis of power plants (~ 100 users worldwide)
• Cycle Tempo Applications
• fuel cell systems
• gas turbine cycles
• combined cycle plants
• combustion and gasification systems
• heat transfer systems • steam turbine cycles
• organic Rankine cycles • refrigeration systems
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Electrochemical Studies Impedance measurements with Ni/GDC anodes Several hundred impedance measurements to get clearer concepts on rate limiting steps Detailed modeling of gas diffusion impedance
Impedance measurements with biosyngas compositions
P.V. Aravind, J.P. Ouweltjes and J. Schoonman. J. Electrochem. Soc., 156(12) B1417-B1422, 2009.
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Impedance measurements with contaminants
Measurements with different contaminants H2S, HCl, tar, KCl 1,2
With naphthalene impedance slightly increased On first look impedance increase is not desirable With detailed modeling it appears that this increase is due to reforming
1) PV Aravind, JP Ouweltjes, N Woudstra, G Rietveld, Elechtrochem. Sol. State Lett. 2008, 11, B24-B28.
2) PV Aravind, PhD Thesis, TU Delft, 2007
Vermelding onderdeel organisatie
16
0
2
4
6
8
10
0 4 8 12 16 20
0mA cm-2 with tar
150mA cm-2 with tar
50mA cm-2 with tar
-Z''(cm
2)
Initial without tar
Z' (cm2)
3
2
1
0
-1
1. Higher current density helps to suppress carbon deposition
2. 10% at 150 mA cm-2 does not ensure a carbon deposition-free scenario
Figure 1. Influence of current density on the impedance spectra of SOFCs
Operating temperature: 800 °C
Operating pressure: Ambient pressure
Anode types: Ni/YSZ
Syngas composition (%): 16 H2, 1.5 CH4, 46.5 N2,16
CO2, 20 CO (10 % steam as of dry gas)
Tar concentration: 6.3 g Nm3
Figure 2. Image of anode microstructure with
carbon deposition (arrow direction) after 5 hours
tar exposure at 100 mA cm-2
Liu, M., M Milan , PV Aravind, N Brandon. (2011). "Influence of Operating Conditions on Carbon Deposition in SOFCs Fuelled
by Tar-Containing Biosyngas.“ Journal of the Electrochemical Society 158(11): B1310-B1318.
Impedance measurements with contaminants
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SOFCs with contaminants- I-V measurements
1) JP Ouweltjes, PV Aravind, N Woudstra, G Rietveld, Journal of Fuel Cell Science and Technology 3 (2006), pp. 495–498
2) PV Aravind, PhD Thesis, TU Delft, 2007
400
500
600
700
800
900
1000
1100
0 100 200 300 400 500
Current density (mA/cm2)
Ce
ll V
olt
ag
e (
mV
)
0 20 40 60 80 100
Fuel utilization (%)
Fuel 1 + 9 ppm H2S
Fuel 8 + 2 ppm H2S
Fuel 10 + 2 ppm H2S
H2 + 2-9 ppm H2S
92% H2 + 8% CH4 + 2 ppm H2S
CH4 + 2 ppm H2S
Different fuels with S, air, 850°C
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SOFC cells and stacks with biosyngas
Principles of mass transfer inside SOFC
Anode gas
Anode
Cathode
Cathode gas
Separator plate
Separator plate
Reaction zone Electrolyte
2e-
O2 (i+1) O2 (i-1) O2-
2e-
H2
CO
CO2
CH4
CO
H2O
H2 (i-1)
CO2 (i-1)
H2O (i-1)
CO (i-1)
CH4 (i-1)
H2 (i+1)
CO2 (i+1)
H2O (i+1)
CO (i+1)
CH4 (i+1)
H2 H2O
H2O H2 CH4 CO2
Electrochemistry integrated Computational Fluid Dynamics for cell performance evaluation L. Fan, E. Dimitriou, M.J.B.M. Pourquie, M. Liu, A.H.M. Verkooijen, P.V. Aravind, Prediction of the performance of a solid oxide fuel cell fuelled with biosyngas: Influence of different steam-reforming reaction kinetic parameters, IJHE, 38 (1) 1-708
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Medium temperature Gas Cleaning Unit- Process Scheme
GCU connected with the gasifier and the
fuel cells
- (1 kW stack)
- Lowest temperature 350 oC
Prototech, 1kW
planar SOFC stack
V-15
E-2
V-19 V-20
V-21 V-22V-23
V-24
V-25E-7 E-8 E-9 E-10
V-26
V-27
P-6 P-7
V-28
V-30
V-31
V-32
V-33
PSI
Tar Protocol
TUD
Gas Analysis
NTUA/TUM
Tar Protocol
TUD Moisture
Measurements
TUD Gas
Analysis
Exhaust, to the
combustion chamber
NTUA test-rig for
planar SOFC cell
TUM, 1kW tubular
SOFC stack
TUM
BioHPR Gasifier
HCl
Removal
1st
stage
H2S
Removal
2nd
stage
H2S
Removal
1st
stage
Tar
cracking
2nd
stage
Tar
cracking
PV Aravind, W de Jong Evaluation of high temperature gas cleaning options for biomass gasification product gas for Solid Oxide Fuel Cells - Progress in Energy and Combustion Science, Volume 38, Issue 6, December 2012, 737–764
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High Temperature Gas Cleaning Unit -Process Scheme
Lowest temp - 600 oC
Contaminants to be removed include 1. Tars 2. Particulates 3. Alkali metal compounds 4. HCl, H2S etc.
21
Gasifier-SOFC experiments: Delft
Experiments carried out at Delft Circulating fluidized gasifier employed SOFCs with Ni/GDC anodes were tested Tests carried out by TU Delft, NTUA, TU Graz and ECN
Medium temperature gas cleaning employed
22
Gasifier-SOFC experiments: Results
No tar With tar
Few thousand ppm tar had no significant impact on SOFC for several hours
P Hofmann,; K D. Panopoulos, P.V. Aravind, M Siedlecki, JP Ouweltjes; A Schweiger, J Karl , E Kakaras. IJHE, 2009, 34:9203 - 9212
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Therm. Eval. : Gasifier-SOFC+GT system with high. temp gas cleaning
PV Aravind, T Woudstra, N Woudstra, H Spliethoff, J. Power. Sources, 190(2): 461-475
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Therm. Eval. : Gasifier-SOFC+GT system with high. temp gas cleaning-2
With highly integrated systems Electrical Efficiencies achievable are around 70%
P V Aravind, C Schilt, B Türker, T Woudstra, International Journal of Renewable Energy Development, 2012, Vol 1, Issue 2, p 51-55
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Integration of a Siemens 5 kW SOFC stack to a biomass gasifier
• Together with Itajuba University Brazil: Industry/NUFFIC-NESO funded
• SOFC system modification and long term testing • Combination of low temperature and high
temperature cleaning units • Gas cleaning system components are being
developed
• PhD students from Delft and Itajuba
M. Liu, P.V. Aravind,T. Woudstra, V.R.M. Cobas, A.H.M. Verkooijen, Development of an integrated gasifier–solid oxide fuel cell test system: A detailed system study, Journal of Power Sources, 196(17), 7277-7289, 2011
Retrofitting SOFC to an operational ~250 MW
IGCC operating on Coal-Biomass mixtures
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1. Fully detailed thermodynamic calculations
2. Second law analysis 3. Operational IGCC 4. Base case models
validated using experimental data
5. >40% efficiencies achievable
6. SOFCs can be retrofitted 7. CCS integration possible
SCWG-SOFC integration project
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1. Dutch national project with industrial participation 2. SCWGs can handle wet biomass and produce cleaner gas mixtures
Preliminary system calculations indicate ~ 50% efficiency for SCWG-SOGFC-GT systems
R. Toonssen, P. V. Aravind,G. Smit ,N.Woudstra, and A. H. M. Verkooijen, System Study on Hydrothermal Gasification CombinedWith a Hybrid Solid Oxide Fuel Cell Gas Turbine, FUEL CELLS 10, 2010, No. 4, 643–653
Reinventing the toilet- the role of SOFCs
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1. Multi million dollar project, all for TU Delft
2. Integrated system development
3. Microwave assisted plasma gasification
4. SOFCs for producing electricity for the plasma gasifier
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Gasifier-SOFC systems: What is achieved
• Clean syngas compositions are fine with SOFCs • Tolerance levels for various contaminants are higher than previously
thought
• State of the art gas cleaning systems are probably sufficient • Successful short duration integrated gasifier-SOFC experiments (>
10000 ppm tar fed to SOFC) • Above 50% electrical efficiency achievable with gasifier-SOFC+GT
systems (possibly even around 70% with highly integrated systems)
• With low temp. gas cleaning, electricity production efficiencies are slightly lower for gasifier-SOFC+GT systems
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Waste Water to Power
Ammonia and fertilizer
production
Ammonia
The project involves
•Production of ammonia from waste
water and urine (by project partners)
•Evaluation of the influence of
contaminants on ammonia fed SOFC
•Demonstration of the concept
•Thermodynamic evaluation and
optimization
• Royal Institute of Engineers award for the project for
innovativeness
• Joint project together with industrial partners
K. Hemmes, P. Luimes, A. Giesen, A. Hammenga, P.V. Aravind and H. Spanjers, Water Practice & Technology, 2011 | doi:10.2166/wpt.2011.007
Modelling SOFC-GT systems for UAVs
DME
Ammonia
Concept 3: PEMFC LH2 fuel, NASA HALE UAV
High Endurance Long Distance
Hurricane science Communications Relay
14 day-flight (180 days goal) 12 day-flight (178 days goal)
Cruise Velocity: 151 km/h Cruise Vel.: 201 km/h
Distance: 5000 km Distance: 3500 km
Cape verde Las Cruces, USA
Altitude: 21km or + Altitude: 18km (21 km goal)
• Base case adopted from- “Craig L. Nickol et al, High Altitude Long Endurance UAV Analysis of alternatives and technology requirements Development, NASA, March 2007” • Present focus- biofuels for such aircrafts
Synthetic Methane Project: Renewable Fuel Production and the role of Electrolysis
32
1. TUD-ECN joint project
2. Detailed system studies and preliminary experiments
34
Summary
1. Biomass need to be converted with highest possible efficiency 2. Solid Oxide Fuel Cell Systems help to achieve high efficiencies in bioenergy conversion 3. Around 70% electrical efficiency achievable with highly integrated gasifier-SOFC-Gas Turbine systems 4. Solid oxide fuel cells can probably tolerate many biomass derived contaminants including tars to certain limits 5. Mobile applications will require production of easy to handle fuels- SOFCs can then be used for electricity production 6. Sanitation systems- potential exists for biofuel production and resource recovery
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