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

8

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

10

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

11

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

SOFC- lab facilities

Electrode, Cell, Stack, and Fuel Processing Test stations

14

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.

15

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

17

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

18

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

19

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

20

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

23

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

24

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

25

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

26

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

27

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

28

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

29

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

30

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

Synthetic Methane Project: Fuel Assisted Electrolysis

33

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

35

Thank You!