recent developments in solid oxide fuel cells · fuel and air electrochemically into electricity...
TRANSCRIPT
Professor Nigel Brandon OBE FREng
Director, Energy Futures Lab
Director, Hydrogen and Fuel Cell SUPERGEN Hub
www.h2fcsupergen.com
www.imperial.ac.uk/energyfutureslab
Recent Developments in Solid Oxide Fuel Cells
Imperial College London
- Established in 2005 to promote and stimulate multi-disciplinary energy research.
- Research income of ~ £28Mpa for energy research, 38% from industry.
- ~600 research staff and PhD students undertaking energy research.
Integrating Themes
-Energy systems engineering
-Energy policy
-Energy business
-Energy in society
The Energy Future Lab| Integrates across Science, Engineering, Policy and Business in
the energy sector
Energy Technologies
-Fuel cells
-Energy storage
-Bio-energy
-Hydrogen
-Solar
-Carbon capture and storage
-Oil and gas
-Smart grids
-Transport systems
-Nuclear fission and fusion
-Electric and hybrid vehicles
-Green aviation
Prof. Nigel Brandon – Imperial College, Dr David Book – Birmingham Univ.,
Prof. Paul Ekins – UCL, Prof. Anthony Kucernak – Imperial College, Dr Tim
Mays – Bath Univ., Prof. Ian Metcalfe – Newcastle Univ., Prof. Vladimir
Molkov – Ulster Univ., Prof. Robert Steinberger-Wilckens – Birmingham
Univ., Prof. John Irvine – St Andrews., Prof. Nilay Shah – Imperial College.
The 1st Annual Conference of the H2FC SUPERGEN Hub will
be held at All-Energy in Aberdeen on May 21st and 22nd 2013
–registration (free) for All-Energy is required for the 22nd.
Everyone is welcome to join the H2FC SUPERGEN Hub as
an Associate Member – see the website or Chloe Stockford
for details. www.h2fcsupergen.com
The Hub organises regular events, and has further funding to
award to eligible UK academic participants.
Content
• Why are Solid Oxide Fuel Cells of interest?
• SOFCs for residential scale mCHP.
• SOFCs for distributed power generation.
• Examples of current research at Imperial College.
• Summary.
Content
• Why are Solid Oxide Fuel Cells of interest?
• SOFCs for residential scale mCHP.
• SOFCs for distributed power generation.
• Examples of current research at Imperial College.
• Summary.
So why are fuel cells of interest?
• A fuel cell is an energy conversion device - it converts
fuel and air electrochemically into electricity (and heat).
•Fuel cells have the highest known efficiency of any
energy conversion device – an efficiency which further
increases at part load.
• By avoiding combustion fuel cells produce extremely
low levels of NOx and particulates.
• Fuel cells are quiet and vibration free to allow a wide
range of siting options, and can be used in a wide
range of mass market applications.
Fuel Processing Options
Thermodynamic predictions of
the equilibrium composition for
methane fed at different
temperatures and steam-to-
carbon ratios. The combined
CH4 + H2O input amount is 1
kmol in each case.
The rise of gas in the United Kingdom
• Over the last 40 years, gas
has become a key player in
the UK energy system
• Seeded by the discovery of
gas in UKCS
• Sustained by a coal -> gas
switch in heating, and
introduction of central heating
• Consolidated by the “dash for
gas” in the 1990s for power
generation
• Rapid growth in shale gas is
also driving gas use in
global markets
The Rise of Gas in the UK Energy System (Gas
Primary Energy Consumption 1970-2011)
Source: Digest of UK Energy Statistics, 2012
IEA Golden Age of Gas Scenario
Gas Demand by Region
2010 2015 2020 2025 2030 20350
1000
2000
3000
4000
5000
6000
Time (years)
De
ma
nd
(b
cm
)
North America
Europe
Pacific
E.Europe Eurasia
Asia
Middle East
Africa
Latin America
International Energy Agency. Are we entering a golden age of gas? Special report in World Energy Outlook 2011.
IEA, Paris, France
Polymer Fuel Cells
•Focus on hydrogen as a fuel, primarily for transport applications. Potential to
de-carbonise the transport sector if hydrogen is produced from nuclear,
renewables, or with CCS.
•Toyota and Daimler have both committed to commercial launch of FCEVs in
2015 – range 700 miles at a vehicle price of $50k in volume.
•30,000 PEMFC mCHP units (0.7 kWe) sold to residential customers in Japan
from April 2011 to March 2012 (JX Nippon Oil and Energy).
Solid Oxide Fuel Cells
•Focus on natural gas for stationary systems, but has the potential to operate
on renewable fuel e.g. biogas.
•Efficiency is high on hydrocarbon fuels (>40% for ‘small’ (kWe) stand alone
systems through to 70% for ‘large’ (MWe) gas turbine hybrids).
•Over 20MWe capacity of Bloom SOFC units installed in USA.
•Over 1000 0.7 kWe mCHP units sold to consumers in Japan since launch in
October 2011. 15,000 hours operation demonstrated – sold with a 10 year
guarantee (JX Nippon Oil and Energy) at 2.5M Yen before 850k Yen subsidy –
net cost to consumer around £11k.
Content
• Why are Solid Oxide Fuel Cells of interest?
• SOFCs for residential scale mCHP.
• SOFCs for distributed power generation.
• Examples of current research at Imperial College.
• Summary.
Fuel
Fuel
Cell Fuel
Heat
Electrical
50%
40%
Energy
100%
Power station
55% losses
Transmission
5% losses
Delivered
40%
Fuel Cell
10% losses Delivered
90%
Energy
100%
Conventional
Micro-CHP
Fuel Cell Boilers for the Home (micro-CHP)
Micro-CHP Technologies
Baxi Stirling engine Panasonic PEMFC
Ceres Power and British Gas SOFC
Honda ECOWILL ICE
Honda ECOWILL ICE with Storage
0 4 8 12 16 20 240
2
4
6
8
10
12
14
16
Time (Hours)
Dem
and (
kW
)
Space Heating and DHW Demand
Electricity Demand
Residential heat and power demand
Heat and Power Demand over 1 Day in a Typical UK Dwelling
Economic Drivers for m-CHP Systems
• Dwelling Annual Electricity Demand •The main value driver for micro-CHP is (the ability to displace) onsite electricity demand.
•If onsite electricity demand exists, the ability to access the value available (in displacing it) is dependent on the heat-to-power ratio (HPR) and presence of thermal demand.
0 2500 5000 7500 100000
200
400
600
800
1000
1200
IC Engine
0 2500 5000 7500 100000
200
400
600
800
1000
1200
PEMFC
0 2500 5000 7500 100000
200
400
600
800
1000
1200
SOFC
0 2500 5000 7500 100000
200
400
600
800
1000
1200
Annual Electricity Demand (kWh/year)
Maxim
um
Cost
Diffe
rence B
etw
een
Mic
ro-C
HP
Syste
m a
nd B
oiler
Syste
m (
£)
Stirling Engine
Low Thermal Demand
Average Thermal Demand
High Thermal Demand
HPR = 1
HPR = 3 HPR = 2
HPR = 8
Dwelling Annual Electricity Demand
Hawkes, AD, Staffell, I, Brett, DJL, Brandon, NP, Fuel Cells for Micro-Combined Heat and Power Generation, Energy &
Environmental Science, 2009, Vol: 2, Pages: 729 - 744
5000 10000 15000 20000 25000 300000
500
1000
1500ICE
5000 10000 15000 20000 25000 300000
500
1000
1500PEMFC
5000 10000 15000 20000 25000 300000
500
1000
1500SOFC
5000 10000 15000 20000 25000 300000
500
1000
1500
Annual Thermal Demand (kWh/year)
Annual C
O2 R
eduction w
.r.t. R
efe
rence S
yste
m (
kg C
O2/y
ear)
)
Stirling
Flat
Bungalow
Terrace
Semi-Detached
Detached
Environmental Drivers for m-CHP Systems
CO2 Reduction – Thermal Demand •CO2 reduction is dependent on ability to displace grid electricity.
•Ability to displace grid electricity, and thus bring about CO2 reduction, is dependent on annual thermal demand and prime mover heat-to-power ratio.
Hawkes, AD, Staffell, I, Brett, DJL, Brandon, NP, Fuel Cells for Micro-Combined Heat and Power Generation, Energy &
Environmental Science, 2009, Vol: 2, Pages: 729 - 744
marginal CO2 intensity of UK
electricity 0.69kgCO2/kWh
Ceres Power SOFC micro-CHP unit
Reduces the energy bill of a customer by around 25% and saves around
1.5 tonnes of CO2 pa. In addition, under the UK feed in tariff (FIT), a
household installing a SOFC mCHP product will receive, for a period of ten
years, a generation payment of 10p/kWh (proposed to increase to 12.5p).
For a typical UK home with a Ceres micro-CHP unit, the annual FIT is £436,
on top of the predicted annual energy cost savings of £286.
© Ceres Power 2013 Title: 8th International Smart Hydrogen and Fuel Cell Conference Rev: 1.0
• Thin steel substrate with even
thinner layers of active SOFC
materials coated on top
• Low temperature electrolyte (ceria)
enables operation at <600 oC
• Key advantages:
– Low cost cells
– Compact, lightweight design
– Mechanically tough
– Simple & reliable stack sealing
– Enables low cost balance of plant
The core of the Ceres proposition is its unique metal-supported cell
10
Stainless Steel Substrate
Anode Layer
Ceria ElectrolyteLayer
Cathode Layer
FUEL
AIR
ELECTRICITY
Slide supplied by Dr Mark Selby, Director of Technology, Ceres Power
© Ceres Power 2013 Title: 8th International Smart Hydrogen and Fuel Cell Conference Rev: 1.0
Enables a compact 1kW-Class Stack
12
o 93 to 140 cells
o Cell fuel side sealing by
laser weld
o Compression maintained at
operating temps; low creep
o Pre-formed high temp
gaskets
o Robust seal created on
compression
o ~50mV max voltage
variation across cells in
stack
Designed for simple manufacture and assembly
191.9mm
152.5mm
Weight - 9.3 kg
Volume - 4.1 l
141.4mm
99 cells variant
Weight - 70 g
Single cell
(Including seal)
Slide supplied by Dr Mark Selby, Director of Technology, Ceres Power
© Ceres Power 2013 Title: 8th International Smart Hydrogen and Fuel Cell Conference Rev: 1.0
Highly compact 1kW Fuel Cell Module (FCM)
Design Specification
Maximum electrical power 1000W DC
Minimum electrical power 300W DC
Electrical efficiency (LHV) 50%
Gas supply Natural Gas
Time to first power 2 hours
Electrical ramp rate 3 W/s
Degradation rate 0.5% / khrs
13
STACK
Fuel
Processor
Hx
Slide supplied by Dr Mark Selby, Director of Technology, Ceres Power
© Ceres Power 2013 Title: 8th International Smart Hydrogen and Fuel Cell Conference Rev: 1.0
CTP able to meet multiple start-stops required by real products
20
Ceres metal-supported fuel cell stacks are robust to repeat start-stops
Stack power measurements
at each cycle showing no
power loss
6 cell short stack:
Sealing, Gaskets, Manifolding,
Current collection identical to
stack used in FCMs and CHPs
56% H2/44% N2
3% H2O in Air
140 mA/cm2
Stack cycled from
operating point (590 oC)
to 100 oC
Test intentionally
stoppedRates are furnace
controlled; not
optimised
Tem
pera
ture
C
Time hrsTest Date: Dec 2011 - Jan 2012
Slide supplied by Dr Mark Selby, Director of Technology, Ceres Power
© Ceres Power 2013 Title: 8th International Smart Hydrogen and Fuel Cell Conference Rev: 1.0
• Emergency Stops – immediate cut-off of fuel and air with a thermal cycle
• Other fuel cell technologies can suffer catastrophic damage under this
condition
95%
Stack power measurements
showing 95% power retention
and no loss of cell integrity
Ceres stacks are robust to harshest cycling challenge possible:
Emergency Stops
7 Cell Stack
21
Test Date: August, 2012
Cells survive unplanned shutdowns (RedOx)
Slide supplied by Dr Mark Selby, Director of Technology, Ceres Power
Content
• Why are Solid Oxide Fuel Cells of interest?
• SOFCs for residential scale mCHP.
• SOFCs for distributed power generation.
• Examples of current research at Imperial College.
• Summary.
2 kWe anode supported
stack at Topsoe Fuel Cells
60 kWe anode supported module from
Versa Power (4 off 15 kWe stacks)
Examples of Leading Developers
Topsoe Fuel Cells and Versa Power
Examples of Leading Developers
Bloom Energy
Examples of Leading Developers
LGFCS and MHI SOFC-GT Systems
LG Fuel Cell Systems IP-SOFC
MHI 200 kW SOFC-GT
Content
• Why are Solid Oxide Fuel Cells of interest?
• SOFCs for residential scale mCHP.
• SOFCs for distributed power generation.
• Examples of current research at Imperial College.
• Summary.
SOFC Anode Behavior, Fabrication and
Design
Illustration of the effect of extending the TPB using a MIEC electrolyte. (a)
Electrolyte / cermet anode with active TPB circled; (b) mechanism of
reaction at the TPB; (c) mechanism of reaction at the extended TPB.
Electrode Microstructure in three dimensions
TPB 2
TPB 3
TPB 1
TPB 2
TPB 3
TPB 1
Tomography of Ni-ScSZ anodes
• Allows feature extraction (Ni/ScSZ/Pores)
• FIBSEM, voxel sizes ~20-50nm
• 1350ºC sintering, 1 hr at temperature,
reduced
A
5 µm 5 µm 5 µm
Ni
30 Vol.%
Ni
40 Vol.%
Ni
50 Vol.%
Ni Ni
ScSZ ScSZ
Pores Pores
Pores
B C
Ni Percolation Threshold
Ni Percolated
Fabrication and characterization of Ni/ScSZ cermet anodes for IT-SOFCs, Somalu MR, Yufit V, Cumming D, Lorente E, Brandon NP,
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 2011, Vol:36, Pages:5557-5566.
Percolated nickel networks
• Ni30 – 65% of Ni is
percolated
A
5 µm 5 µm 5 µm
Ni
30 Vol.%
Ni
40 Vol.%
Ni
50 Vol.%
Ni Ni B C
Considered Ni
Percolation Threshold Considered Ni Percolated Considered Ni Percolated
• Ni40 – 97% of Ni is
percolated
• Ni50 – 90% of nickel is
percolated
Preliminary results indicate:
Ni 646
Pores 1317
ScSZ 1345
Ni 2481
Pores 2976
ScSZ 4195
Ni 1594
Pores 1999
ScSZ 2130
Surface Area of particles in total volume analysed (x 103 m-1)
In-situ imaging of LSCF cathode at 700C
Using Synchrotron X-Ray Nano-CT to Characterize SOFC Electrode Microstructures in Three-Dimensions at Operating Temperature
P.R. Shearing , R. Bradley , J. Gelb , S. Lee, A. Atkinson, P.J. Withers, N.P. Brandon, Electrochem. S.S. Lett. 14 (10) (2011) B117-B120.
• Size and type of carbon deposits can be determined from Raman spectra
• Carbon powders indistinguishable in white light
• Raman shows clear differences in key features allowing us to say: – Carbon A amorphous
– Carbon B highly graphitic
– Carbon C graphitic
Carbon formation studied using ex-situ Raman
1000 1500 2000 2500 3000
0
1000
2000
3000
4000
5000
6000
Inte
nsity (
arb
.)
Raman shift (cm-1)
Carbon A
Carbon B
Carbon C
The Application of Raman Spectroscopy to Solid Oxide Fuel Cells, R. C. Maher, V. Duboviks, G. J. Offer, M. Kishimoto, N. P. Brandon and L. F. Cohen,
Fuel Cells, accepted for publication.
SOFC test rig for in-situ and in-operando
Raman measurements
Brightman, E., Maher, R., Offer, G. J., Duboviks, V., Heck, C., Cohen, L. F. Brandon, N.P., Designing a miniaturised heated stage for in-situ optical measurements of SOFC electrode surfaces, and probing the oxidation of SOFC anodes using in-situ Raman spectroscopy, Rev. Sci. Instrum. 83, (2012)
Combined electrical and optical measurements critical
• 10 input/outputs in basic mode
• 2 electrode operation
• Passive cathode circulation
• 14 input/outputs in full mode
• 3 electrode operation
• Active cathode circulation
• Active air cooling of objective
• All in a 2cms (d) by 1cm (h) ‘hot zone’
• Excitation: 488, 514, 633, 780 and 830nm
• Mapping stages with 0.1µm resolution
SOFC test rig for in-situ and in-operando
Raman measurements
Brightman, E., Maher, R., Offer, G. J., Duboviks, V., Heck, C., Cohen, L. F. Brandon, N.P., Designing a miniaturised heated stage for in-situ optical measurements of SOFC electrode surfaces, and probing the oxidation of SOFC anodes using in-situ Raman spectroscopy, Rev. Sci. Instrum. 83, (2012)
In-situ & in-operando Analysis – dry CO
1200 1400 1600 1800400
500
600
700
800
Inte
nsity (
arb
.)
Early stage growth
Late stage growth
Raman shift (cm-1)
0 500 1000 1500
-20
0
20
40
60
80
100
120
140
160
Time (s)
Inte
nsity (
arb
.)
D Peak intensity
G Peak intensity
• NI-CGO anode
• 514nm, 15 sec/pt, 1.5 mm
• Pure dry CO at 600oC – Open circuit potential (OCP)
remains stable
– Initial carbon formation rapid, then plateaus
– Predominantly Graphitic Carbon
0 500 1000 1500 2000-1.20
-1.15
-1.10
-1.05
-1.00
-0.95
-0.90
-0.85
-0.80
Op
en
cir
cu
it p
ote
ntia
l (V
)
Time (s)
The Application of Raman Spectroscopy to Solid Oxide Fuel Cells, R. C. Maher, V. Duboviks, G. J. Offer, M. Kishimoto, N. P. Brandon and L. F. Cohen,
Fuel Cells, accepted for publication.
1200 1400 1600 1800
600
800
1000
1200
1400
1600
1800
Inte
nsity (
arb
.)
Early stage growth
Late stage growth
Raman shift (cm-1)
0 500 1000 1500
0
50
100
150
200
250
300
Inte
nsity (
arb
.)
D Peak intensity
G Peak intensity
Time (s)
• Ni-CGO anode
• 514nm, 15 sec/pt, 1.5 mm
• Dry CO & H2 at 600oC – Open circuit potential (OCP)
decays with time
– Initial carbon formation slower, but continuous
– Damage visible and profound
0 500 1000 1500 2000-1.20
-1.15
-1.10
-1.05
-1.00
-0.95
-0.90
-0.85
-0.80
Op
en
cir
cu
it p
ote
ntia
l (V
)
Time (s)
In-situ & in-operando Analysis – dry H2 -CO
The Application of Raman Spectroscopy to Solid Oxide Fuel Cells, R. C. Maher, V. Duboviks, G. J. Offer, M. Kishimoto, N. P. Brandon and L. F. Cohen,
Fuel Cells, accepted for publication.
Effect of current density – Ni-CGO anode
in dry CO at 600C
The Application of Raman Spectroscopy to Solid Oxide Fuel Cells, R. C. Maher, V. Duboviks, G. J. Offer, M. Kishimoto, N. P. Brandon and L. F. Cohen,
Fuel Cells, accepted for publication.
Summary
• SOFCs are now available commercially and are of
growing importance as a high efficiency energy
conversion devices for hydrocarbon fuels such as
natural gas and LPG.
• But to compete in the long term against other low
carbon options, and indeed to enable support in the
short to medium term, it is essential to look at lower
carbon fuel options related to the ‘decarbonisation’ of
gas.
• This sets research and technology challenges relating
to the cost effective and durable operation of SOFCs
with renewable fuel sources.
Thank you
mCHP: Adam Hawkes, Iain Staffell, Dan Brett (UCL).
Tomography and 3D structures: Farid Tariq, Khalil Rhazaoui, Sam Cooper,
Masashi Kishimoto, Guansen Cui, Prof. Claire Adjiman, Qiong Cai (Surrey),
Paul Shearing (UCL), David Eastwood, Peter Lee, Phil Withers (Manchester).
Raman and surface processes: Greg Offer, Rob Maher, Vladislav Duboviks,
Michael Parkes, Nic Harrison, Lesley Cohen, Stephen Skinner, John Kilner.
Electrode fabrication and electrochemistry: Enrique Ruiz-Trejo, Paul Boldrin,
Marina Lomberg, Vladimir Yufit, Alan Atkinson.
Integration with renewable fuels: Marcos Millan-Agorio, Elsa Agante.
Financial support from the EPSRC, EU and ONR. Synchrotron data was
collected at beam-line XOR 32-ID at the Advanced Photon Source at Argonne
National Laboratory supported by the U.S. Department of Energy, Office of
Basic Energy Sciences.
Further details on Fuel cell and hydrogen research in the UK can be found at
the Hydrogen and Fuel Cell SUPERGEN Hub www.h2fcsupergen.com