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Transcript of Superconductivity UK Dr. Philip Sargent, Diboride Conductors Ltd. Commercial superconductors,...
Superconductivity UK
Dr. Philip Sargent, Diboride Conductors Ltd.
Commercial superconductors, Cryogenics and Transformers
This Talk
• Materials Review and price predictions• BSCCO
• MgB2
• YBCO
• Cryogenics considerations
• Superconducting Transformers
Commercial Wire & Tape
• Commercial production:
• Niobium alloys (NbTi, Nb3Sn etc)
• B2223 / silver tape - 1st Generation HTS
• Pre-commercial:• MgB2
• Industrial laboratory:• YBCO 2nd Generation HTS “coated conductor”
Key issues for power applications• Overall current density JJee of conductor, not just of superconductor
• Performance in field
• Multiple filaments for AC applications
• Anisotropy of Jc with respect to field direction
• Cost!• Conductor itself
• Cooling (AC losses)
• Scalability of fabrication
• Mechanical • Strength, bend radius
HTS –perovskite ceramics
Cu
OBa
Y
Ba
YBCO - YBa2Cu3O7B2223 - Bi2Sr2Ca2Cu3O
Engineering Implications
• Requires near single-crystal microstructure by complex processing,
• Oxide requires furnace treatment in controlled oxygen atmosphere, in silver,
• Highly anisotropic resulting tape:• Along and across tape,
• Sensitive to magnetic field direction!
AMSC & Sumitomo
• AMSC & Sumitomo have a reciprocal licensing agreement
American Superconductor 55 filament (B2223) tape
Sumitomo (B2223) tape
AMSC B2223 Manufacturing Plant
Larger billets, Process automation, Longer Larger billets, Process automation, Longer strands, Multi-dies, Faster line-speed, strands, Multi-dies, Faster line-speed, Combination of process stepsCombination of process steps
Began volume production in early 2003Began volume production in early 2003
Full capacity could be 20,000 km/year, now Full capacity could be 20,000 km/year, now 900 km/year900 km/year
• How much does it cost to buy the wire to carry 1000 Amps a distance of 1m?
• Copper: 6 $/kA.m – 22 $/kA.m depending on current density (400 – 100 A/cm2)
• Superconductors typically quoted at Jc and at 77K and either zero magnetic field or “self field”.
• Cryogenic OFHC copper can be 0.06 $/kA.m.• NbTi is approx. 0.9 $/kA.m in liquid helium.
Price/Performance $/kA.m
Reduced Manufacturing Costs ($/m) Reduced Manufacturing Costs ($/m) andand Increased Wire Increased Wire Performance (current carrying capacity)Performance (current carrying capacity)
Reduced Manufacturing Costs ($/m) Reduced Manufacturing Costs ($/m) andand Increased Wire Increased Wire Performance (current carrying capacity)Performance (current carrying capacity)
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
$/kA.m
0
200
400
600
800
1000
1200P
rice
/Per
form
ance
Rat
io, $
/kA
-m
World’s First HTS Wire Manufacturing Plant
Opened By AMSC
Price/Performance $/kA.m
200 $/kA.m
B2223 & Commercial Products• At $50/kAm (77K) price/performance ratio
significant markets would be enabled (it was thought in ~1999):− Utility Generators (>100MVA)Utility Generators (>100MVA)
− Ship Propulsion Motors and Generators (>5MW)Ship Propulsion Motors and Generators (>5MW)
− Wind Turbine Generators (>4MW)Wind Turbine Generators (>4MW)
− Urban T&D Power CablesUrban T&D Power Cables
− Industrial Magnetic ProcessingIndustrial Magnetic Processing
• Significant worldwide industry in B2223American Superconductor, Innova, Nordic Superconductor, Sumitomo American Superconductor, Innova, Nordic Superconductor, Sumitomo Electric, Vacuumschmelze, TrithorElectric, Vacuumschmelze, Trithor
Bought and shut down by AMSC in 2002
Magnetic Field
• High magnetic field reduces current carrying capacity
• Lower temperatures enhance current carrying capacity
• Transformers, cables and FCLs are low magnetic field devices
• B2223 at 27K carries twice the current, so $/kA.m reduces to 100 $/kA.m.
Diboride & YBCO
• YBCO and similar compounds have had research worth $$billions devoted to their physics and processing.
• MgB2 was discovered in January 2001; physics now entirely understood.
• Both can be made in:• Tape geometry• Massive lumps for new motor designs
Mg
Mg
Mg
Mg
B
B
B
Magnesium Diboride
Magnesium Diboride
~ 400 $/kg
Making Diboride tape
Cu-sheathed tape
transverse cross section
Tube filling with MgB2 powder
Wire drawing and/or rolling
Flat rolling
Long lengths can be now fabricated
irregular cross section
Simple sintering ~700C
In situ B+Mg with Fe barrier in Monel Sheath
With iron –tough to make multifilament- most likely be cabled ,(twisted) monofilaments for low AC loss conductor, working onOuter sheaths of Monel, Cu/Ni, and Cu to improve stabilization.
Hyper Tech Research
Magnesium Diboride (MgB2 )• Advantages
• No weak-link effects, low anisotropyNo weak-link effects, low anisotropy• Easy to fabricate wires, films: <$10/kA.m potentialEasy to fabricate wires, films: <$10/kA.m potential
• Challenges • TTcc < 40 K (77 K applications like cables, transformers not viable) < 40 K (77 K applications like cables, transformers not viable)• High field applications such as NMR not viableHigh field applications such as NMR not viable
• Possible applications in 20-30K range for modest field environments, e. g., rotating machinery
YBCO Coated Conductor
• Rolled, textured Nickel tape (Ni-W)• Oxide buffer layer, preserves texture• YBCO (or analogue, e.g. HoBCO), preserves texture
• Near “single crystal” 100s of metres longNear “single crystal” 100s of metres long• <$10/kA.m potential, but extraordinary plant cost<$10/kA.m potential, but extraordinary plant cost
YBCO
Ni tape
Oxide buffer layer deposition
YBCO
YBCOprecursor
YBCO oxygenationand conversion
YBCO Coated Conductor tape
• Active programs in US, Japan and Europe
• Examples of results in 2001: • 122 A (75 K) over 1 m by LANL122 A (75 K) over 1 m by LANL
− World record for meter lengthWorld record for meter length
• 50 A over 10 m by Fujikura50 A over 10 m by Fujikura− World record for 10 meter lengthWorld record for 10 meter length
• Over 60 m :FujikuraOver 60 m :Fujikura− World’s longest processed tapeWorld’s longest processed tape
YBCO CC Technical Issues• Adequate uniformity over length
• Stability to over-currents or cracks
• Adequate current in MOD films
• Mechanical properties – spalling, cracking
• Stability of metal-oxide epitaxial interface
• Deposition rate for ion beam and laser processes
• Thicker than 3 micron YBCO ?
• …but must have that 10 $/kA.m process!
B2223 (1G) to YBCO (2G)
Reduced Manufacturing Costs ($/m) Reduced Manufacturing Costs ($/m) andand Increased Wire Increased Wire Performance (current carrying capacity)Performance (current carrying capacity)
Reduced Manufacturing Costs ($/m) Reduced Manufacturing Costs ($/m) andand Increased Wire Increased Wire Performance (current carrying capacity)Performance (current carrying capacity)
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
$/kA.m
0
200
400
600
800
1000
1200P
rice
/Per
form
ance
Rat
io, $
/kA
-m
World’s First HTS Wire Manufacturing Plant
Opened By AMSC
Price/Performance $/kA.m
200 $/kA.m
ORNL Model
Assumed by analogy with other fibresB2223/YBCO Wire cost ($/kA.m)
Magnesium Diboride
Effort
Pe
rfo
rman
ce
Technology ‘S’ Curves
Effort
Pe
rfo
rman
ce
Copper-Iron
HTS g1
MgB275y 17y
2003
HTS g2
Power Technologies
Conclusions:Superconductors for AC Power
• HTS G1:• B2223 tape
• Diboride:• MgB2 wire
• HTS G2:• YBCO CC tape
AC Power Superconductors
Refigeration Energy Consumption
Carnot Thermodynamics
0 20 40 60 80
Temp (K)
En
erg
y C
on
su
mp
tio
n
Higher running costs, lower wire costs
Lower running costs,uses more wire
Higher running costs = Higher cryogenic capital costs Higher magnetic field
capability
Temperatures
0 20 40 60 80
T (K)
He
H
Ne
O
N
CO
Liquid Phase at 1 atmosphere
Cryogen Gap
Cryogenic Cooling Costs
Ideal Energy Consumption
0.00
20.00
40.00
60.00
80.00
0 20 40 60 80
Temp (K)
EC
Carnot
Sterling27K
77K
10.1x
70.4x
4K
2.9x
14x 9x
30
Cryogenics
• High AC power is intrinsic to transformers
• Cables have high losses: so need cryogens
• Conduction-cooled designs need exploring 20-24K and 27K-60K for other applications
• Thermal reservoirs need investigating to peak-shave cryogenics capital costs
• Reducing the capital cost of cryogenics is as important as their efficiency for grid markets
Cooling & Purchase Costs
• There is a trade-off between cryogenic capital cost and materials capital cost – colder running means less material required but more cryogenics.
• The cheaper the superconductor, the higher the optimum operating temperature.
• Comparing different materials therefore requires a whole-system comparison
• Competition between materials is application dependent
• Transport applications are always more attractive
Cost “Prediction”
Source: Mulholland et al, DOE June 2003
Cryogenic PatentsCryogenic Cooling System patents filed in the U.S.
0
2
4
6
8
10
12
14
16
18
20
Year
Num
ber of
Pat
ents
File
d
Cryogenic Cooling System Patents
Cryocooler
Qi3 Limited (2003)
Targets
• Copper: 6 – 22 $/kA.m (400 to 100 A/cm2)• B2223: 100 $/kA.m (at 27K)
Device kA/cm2 Tesla $/kA.m
Static Transformer
105 1.4 15
Cables 105 <0.1 10 ?
Dick Blaugher, NREL
ABB HTS Transformer100 MVA, 225 / 20 kV• oil free, liquid nitrogen 68K
• 20% lower weight
• 80% lower load losses
• 5% smaller volume
• Short circuit reactance 50% of conventional
• 25% over-loadability without accelerated ageing
• 150% first cost
• 90% lifecycle cost
• Short circuit current limitation in first half wave, self restoring FCL
11 m
135 000 kg
5 m
Other HTS Transformer Benefits
• Reduced need for load tap changer units
• Reduced system VAR requirements
• Reduction in capacitor banks
• With a generator, reduced VAR enables additional generator capacity so reduced capital cost of generator
ABB Conclusions
•With current costs for energy and equipment, an open loop refrigeration system is the most economical.
•The mechanical refrigeration industry is not currently able to meet performance targets required for a commercial Utility product.
–Cryocoolers are too expensive, maintenance intervals are too short, and production methods are not cost effective.
–The number of competitors in the field is limited, and the companies are generally small operations.
–Production scale-up and comprehensive global service could be problematic
Near term market too small to justify continuation of project!
Waukesha/ORNL Project
• Waukesha 24.9kV to 4.2kV
• $10m project
• 2x overload capability
• FCL capability
• 1 MVA pilot at 25K with cryocooler
TransformersLifetime Cost of Ownership in $/kW
2000 ABB SPI Phase I Analysis
Cu (330 K)@ 300 A/cm2
HTS (68 K) 200$/kAm
MgB2 (25 K)
Losses 60
Cryo -
Wire 5
Total 65
5
25
50
80
5 10
34
5
50
Adapted from Paul Grant EPRI
ORNL HTS Transformer
• High utilization and high cryocooler efficiency required to get energy savings (RAND)
• Feasible with 10-year payback if <15$/kA.m at 77K. (Lawrence Assc.)
Energy Efficient Transformers
• High-copper section designs
• Domain-refined steels
• Ultra-thin iron laminations
• High-field (1.7T) iron alloy core
• Metallic glass or amorphous iron core
• Lowest first-cost purchasing prevents adoption of any of these technologies.
www.efficient-transformers.org
Primary Benefit
• The primary benefit in a superconducting transformer is the Fault Current Limiting capability.
• Therefore, make FCLs first!
Thankyou
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