Superconductivity UK

1
Superconductivity UK
Commercial superconductors, Cryogenics and
Transformers
Dr. Philip Sargent, Diboride Conductors Ltd.
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This Talk

• Materials Review and price predictions
• BSCCO
• MgB2
• YBCO
• Cryogenics considerations
• Superconducting Transformers

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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

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Key issues for power applications

• Overall current density Je 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

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HTS perovskite ceramics
YBCO - YBa2Cu3O7
B2223 - Bi2Sr2Ca2Cu3O
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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!

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AMSC Sumitomo

• AMSC Sumitomo have a reciprocal licensing
  agreement

American Superconductor 55 filament (B2223) tape
Sumitomo (B2223) tape
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AMSC B2223 Manufacturing Plant

• Larger billets, Process automation, Longer
  strands, Multi-dies, Faster line-speed,
  Combination of process steps
• Began volume production in early 2003
• Full capacity could be 20,000 km/year, now 900
  km/year

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Price/Performance /kA.m

• 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.

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Price/Performance /kA.m
1200
/kA.m
1000
800
Price/Performance Ratio, /kA-m
600
Worlds First HTS Wire Manufacturing Plant
Opened By AMSC
400
200
200 /kA.m
0
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
Reduced Manufacturing Costs (/m) and Increased
Wire Performance (current carrying capacity)
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B2223 Commercial Products

• At 50/kAm (77K) price/performance ratio
  significant markets would be enabled (it was
  thought in 1999)
• Utility Generators (gt100MVA)
• Ship Propulsion Motors and Generators (gt5MW)
• Wind Turbine Generators (gt4MW)
• Urban TD Power Cables
• Industrial Magnetic Processing
• Significant worldwide industry in B2223
• American Superconductor, Innova, Nordic
  Superconductor, Sumitomo Electric,
  Vacuumschmelze, Trithor

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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.

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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

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Magnesium Diboride
s
39K
p
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Magnesium Diboride
400 /kg
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Making Diboride tape
Simple sintering 700C
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In situ BMg with Fe barrier in Monel Sheath
With iron tough to make multifilament- most
likely be cabled , (twisted) monofilaments for
low AC loss conductor, working on Outer sheaths
of Monel, Cu/Ni, and Cu to improve stabilization.
Hyper Tech Research
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Magnesium Diboride (MgB2 )

• Advantages
• No weak-link effects, low anisotropy
• Easy to fabricate wires, films lt10/kA.m
  potential
• Challenges
• Tc lt 40 K (77 K applications like cables,
  transformers not viable)
• High field applications such as NMR not viable
• Possible applications in 20-30K range for modest
  field environments, e. g., rotating machinery

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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 long
• lt10/kA.m potential, but extraordinary plant cost

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YBCO
Ni tape
Oxide buffer layer deposition
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YBCO
YBCOprecursor
YBCO oxygenationand conversion
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YBCO Coated Conductor tape

• Active programs in US, Japan and Europe
• Examples of results in 2001
• 122 A (75 K) over 1 m by LANL
• World record for meter length
• 50 A over 10 m by Fujikura
• World record for 10 meter length
• Over 60 m Fujikura
• Worlds longest processed tape

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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!

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B2223 (1G) to YBCO (2G)
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Price/Performance /kA.m
1200
/kA.m
1000
800
Price/Performance Ratio, /kA-m
600
Worlds First HTS Wire Manufacturing Plant
Opened By AMSC
400
200
200 /kA.m
0
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
Reduced Manufacturing Costs (/m) and Increased
Wire Performance (current carrying capacity)
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ORNL Model
Assumed by analogy with other fibres B2223/YBCO
Wire cost (/kA.m)
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Technology S Curves
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Power Technologies
75y
17y
Performance
HTS g1
Copper-Iron
2003
Effort
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ConclusionsSuperconductors for AC Power

• HTS G1
• B2223 tape
• Diboride
• MgB2 wire
• HTS G2
• YBCO CC tape

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AC Power Superconductors
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Temperatures
Liquid Phase at 1 atmosphere
CO
N
O
Ne
H
He
0
20
40
60
80
T (K)
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Cryogenic Cooling Costs
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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

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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

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Cost Prediction
Source Mulholland et al, DOE June 2003
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Cryogenic Patents
Qi3 Limited (2003)
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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 lt0.1 10 ?
Dick Blaugher, NREL
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ABB HTS Transformer

• 100 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

5 m
11 m 135 000 kg
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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

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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!

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Waukesha/ORNL Project

• Waukesha 24.9kV to 4.2kV
• 10m project
• 2x overload capability
• FCL capability
• 1 MVA pilot at 25K with cryocooler

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TransformersLifetime Cost of Ownership in /kW
Cu (330 K) _at_ 300 A/cm2 HTS (68 K) 200/kAm MgB2 (25 K)
Losses 60
Cryo -
Wire 5
Total 65
2000 ABB SPI Phase I Analysis
Adapted from Paul Grant EPRI
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ORNL HTS Transformer

• High utilization and high cryocooler efficiency
  required to get energy savings (RAND)
• Feasible with 10-year payback if lt15/kA.m at
  77K. (Lawrence Assc.)

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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
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Primary Benefit

• The primary benefit in a superconducting
  transformer is the Fault Current Limiting
  capability.
• Therefore, make FCLs first!

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Thankyou
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Motor images
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More images